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Posted By: UnrightTooner "Oilcanning" Soundboard Skeptic - 11/28/19 03:08 AM
We often hear of the danger of having the untensioned downbearing on a soundboard greater than the crown due to it causing the soundboard to "oilcan" resulting in negative downbearing. I do not recall this ever being challenged, but the more I think about it, the more I doubt the analogy is accurate. Not to say that having so much downbearing is a good idea, nor that you may end up with negative downbearing on some parts of the soundboard, but for the soundboard to act like an oilcan? No, I don't think so.

When pushing on the bottom of an oilcan with the spout down, the bottom is concave against your thumb at first. As you push harder, the outside surface of the metal is under compression while the inside is under tension. There is more and more resistance as you push further until it suddenly gets easier as the inside of the metal comes under tension while the outside is under compression. This is the point where the metal is now convex against your thumb. The shape has inverted. Yet the metal is still pushing against your thumb, just not as hard, until you allow the metal to regain its shape.

Now consider how the analogy with a soundboard doesn't quite work. When the soundboard supposedly "oilcans", the result is negative downbearing. The soundboard is pulling the strings downward. But with an oilcan, you must continue to push on the can to maintain the oilcan effect!

It could be argued that it is still like an oilcan because you could push on the outer circumference and get the metal to invert. And so excessive downbearing on the perimeter of a soundboard could cause the soundboard to invert resulting in negative downbearing in the middle of the board. But would the soundboard need to invert like an oilcan, and more to the point could it? I don't think so.

On every old piano I have bothered to check downbearing on there has been little, or even negative downbearing around the treble strut compared to higher or lower on the bridge. It's a weak point due to the bridge being notched, or at least not having a bridge cap. Does this mean the soundboard is "oilcanned", that the top of the board is under tension and the bottom is under compression? Of course not, and for those of the buttressed arch soundboard model persuasion, the case will prevent the soundboard from inverting anyway. wink

But couldn't a soundboard invert, like if an elephant stood on it? Well, maybe, but we are talking about the downbearing of strings on a board about 3/8" thick. I would expect on even the flimsiest soundboard that at least 3/8" of downbearing would be necessary to invert a soundboard, where suddenly it would be easier to push the soundboard down. Has anyone ever measured that much untensioned downbearing? And remember, as the strings are tensioned, the downbearing decreases resulting in less, not more, force on the soundboard - just the opposite of what is required for the "oilcanning" analogy to be accurate.

Comments?
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/28/19 03:36 AM
Jeff,

As I understand it, the term is used simply to describe the appearance of the board (almost always under the bridge) under tension and DB. Personally, I cannot recall a situation where the SB STAYED that way after being de-stressed. Possibly others have.

However, the very first time (35 years or so ago) that I saw this was in a SS B that had its SB replaced. As it turned out, upon de-stressing it was found to have roughly what you calculated for DB in order to collapse the board, though it showed zero DB in its strung state. Upon correcting the situation the piano turned out to be quite awesome.

It is interesting to me that you hit the nail on the head.

Pwg
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 11/28/19 12:01 PM
Originally Posted by P W Grey
Jeff,

As I understand it, the term is used simply to describe the appearance of the board (almost always under the bridge) under tension and DB. Personally, I cannot recall a situation where the SB STAYED that way after being de-stressed. Possibly others have.

However, the very first time (35 years or so ago) that I saw this was in a SS B that had its SB replaced. As it turned out, upon de-stressing it was found to have roughly what you calculated for DB in order to collapse the board, though it showed zero DB in its strung state. Upon correcting the situation the piano turned out to be quite awesome.

It is interesting to me that you hit the nail on the head.

Pwg


Thanks for the reply, Peter. Can you explain more what the situation with the B was? What correction was made? When strung, did ALL the strings show zero downbearing? I can only imagine this to be possible if it was that way before being strung. You say the board was collapsed, yet regained its shape when unstrung. OK, a board in a strung piano with DB would do the same. So is it that the board is "collapsed" (and what does that mean...) or that after being strung some notes have zero or negative DB?

Gosh, I hope you don't think I am trying to badger you. Looking for better understanding of what is said on the subject by striving for clear definitions. smile
Jeff,
I think your approach of trying to understand soundboards is from the wrong perspective. Which is from a mechanical point of view. It would be very similar to judging a singers appearance before hearing the sound they produce.
Listen first, and then the board will tell you if its working properly or not.
What I listen for is Messa di Voce. If a soundboard has any problems such as loss of crown, excessive downbearing, or age related fatigue, then messa di voce will have problems. It will be either non existent, weak, or pulsating and diminishing. Crown in itself is not a complete indicator either. The main principle of crowning in musical instruments is to get acoustical intensity by creating internal forces. When soundboards are made with the crown parallel to the grain, the soundboard is put under tension. When a soundboard is crowned perpendicular with the grain, compression is used. When a soundboard is carved, a soundpost is used. This is why piano soundboard repairs offer diminishing returns, because they only repair the mechanical aspect, but do nothing towards regaining messa di voce.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 11/29/19 12:18 AM
Thanks you Mr. C. Yes you are correct. I am looking at this from a mechanical point of view because that is how the "oilcanning" of soundboards has been described. And perhaps you are also right that this is the wrong way to try to understand soundboards. But I am not trying to understand how soundboards affect the tone. Rather I am questioning the analogy of "oilcanning" when parts of a soundboard exhibit zero or negative downbearing.

I have to admit I had to look up the term Messa di Voce. It made me smile. I remember in HS band competitions, while in the waiting room, the other baritone horn players brushing up the most difficult passages. Instead I would slowly play scales, a long 8 counts each note, from pp to ff back to pp (Messa di Voce). It drove the others nuts and I believe made them less confident. It wasn't my purpose even though it was entertaining. I just didn't want to lose my own confidence by making a bunch of mistakes just prior to the try-outs.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/29/19 12:28 AM
Jeff,

The piano exhibited the following symptom:

1) INCREDIBLE tuning instability

2) Sustain was somewhat short...not a pleasing piano to play

3) Hammers were ROCK HARD, had been juiced to the max, impossible to get needles into

4) DB measured while strung showed no measurable DB...appeared flat

5) Underside showed inverted crown under the bridge, positive crown elsewhere

At some point I had replaced the hammers (I believe this was before I started looking at DB and crown). The result was that there was no volume in the piano. I ended up having to juice them to the max JUST LIKE THE PREVIOUS SET.

After I found the DB/crown situation I pronounced the piano as DOA needing a rebuild, on the ASSUMPTION that the soundboard had collapsed and was useless. This was a school and they opted to wholesale the piano to a rebuilder colleague of mine (I made sure he knew it was a basket case) and just get another piano.

One must bear in mind here that I had only been in the business about 10 years at this point and my diagnosis and rebuilding abilities were not what they are now.

Well, i got a call from him sometime later after he had fixed it. He wanted to thank me profusely as the only problem with it was that it had MASSIVE DB and was "oil-canning" the board, resulting in the symptoms I described. He said all he needed to do was fix the DB (by shimming the aliquots), and the piano was fantastic! He made a lot of $$$ on that piano.

I have subsequently learned that this symptom picture (as described above in total) is an indicator of too much DB, uneven DB, or a combination of both. I have proved it several times and suspected it several more times.

Ask away!

Pwg
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 11/29/19 01:22 AM
"Ask away!" Thanks, I guess I will. smile

The 2nd hand info about the SS-B just defies logic in my mind and so I must remain skeptical. Sure, I agree lack of DB can result in instability and a thin tone, regardless of the reason. But for there to be no DB (anywhere?) until the piano is unstrung, and then there is massive DB??? Perhaps something was done with the nose bolts...

But you say you have proved similar symptoms to be caused by too much DB, etc. OK, can you give one or two examples?
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/29/19 04:27 AM
The DB was squashing the board at the bridge, giving the ILLUSION of no DB. It had GOBS of DB...too much, such that it was distorting the board and it would convulse wildly with the slightest change in humidity. Also, there was so much pressure the the board could not vibrate properly which was the reason for short sustain and lack of volume with normal hammers (thus the need to juice them up to get anything at all like a B).

At any rate, this and other cases have caused me to conclude that it is impossible to get a TRUE picture of the DB situation in a strung piano. It needs to have the pressure off, look at the deflections, look at the crown...then decide.

Pwg
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/29/19 04:43 AM
You asked for examples after this one. Initially I did not come to my conclusions based on just that one experience. I was baffled for a while.

Some time later, actually it was when the space shuttle exploded (I remember because I was stringing the piano when I heard the news), had opportunity to restring a fairly new SS M. I had been tuning this piano since brand new, but was perplexed by its seeming extreme tuning instability (even with humidity control). I had no explanation other than still kind of new, and it's just that piano. Due to an accident with a cleaning person that turned the bass strings black, the owner said restring the entire piano (money was no object). So it came into the shop.

Well, upon de-stringing I found what I considered to be excessive DB throughout the treble bridge. Not yet correlating the previous piano I simply reset the bearing to what I saw fit (basically equal to the amount of available crown) by shimming the aliquots, and restrung it.

To my surprise, this piano soon became VERY stable in its tuning, and seemed to blossom in its tone. The only thing I could attribute it to was correcting the bearing. That was when I started putting 2 & 2 together. Could they be related? I believe so.

Pwg
Posted By: kpembrook Re: "Oilcanning" Soundboard Skeptic - 11/29/19 05:05 AM
Hmm... interesting.
Never thought that downbearing issues could affect tuning stability.
I had a piano once that was completely dead. Took the strings off, and the soundboard was completely flat. Popped the board out, and immediately had a full crown. My guess is that it was under full compression the whole time, but it could never crown up because of it being glued in prematurely.
-chris
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 11/29/19 10:43 AM
Originally Posted by kpembrook
Hmm... interesting.
Never thought that downbearing issues could affect tuning stability.


The way I look at it, Keith, is by imagining two people pulling on opposite ends of a rope. If I grab the middle of the rope and pull sideways an inch, it takes very little effort to draw the two people a little closer. But the next inch takes more effort, and if I want to deflect the middle of the rope a foot, it takes even more effort.

And so when there is little or no DB it takes less movement of the soundboard to change the tension of the string than if there is reasonable DB. In a case as Peter just described, where excessive DB in one part of the soundboard causes less DB in another part, a change in humidity would change the string tensions very differently from one part of the scale to another. Same thing if you are pitch raising after such a humidity change.

Speaking of which, when I pitch raise (aurally), I generally give more of a pitch raise around the treble break because I can count on that area dropping in pitch more than the lower tenor and higher treble as I go up the scale. That is even with "distributing" the pitch raise by raising one string on all the unwound F's, then F#'s, etc. I rough in a temperament octave first, of course.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 11/29/19 11:03 AM
Originally Posted by P W Grey
You asked for examples after this one. Initially I did not come to my conclusions based on just that one experience. I was baffled for a while.

Some time later, actually it was when the space shuttle exploded (I remember because I was stringing the piano when I heard the news), had opportunity to restring a fairly new SS M. I had been tuning this piano since brand new, but was perplexed by its seeming extreme tuning instability (even with humidity control). I had no explanation other than still kind of new, and it's just that piano. Due to an accident with a cleaning person that turned the bass strings black, the owner said restring the entire piano (money was no object). So it came into the shop.

Well, upon de-stringing I found what I considered to be excessive DB throughout the treble bridge. Not yet correlating the previous piano I simply reset the bearing to what I saw fit (basically equal to the amount of available crown) by shimming the aliquots, and restrung it.

To my surprise, this piano soon became VERY stable in its tuning, and seemed to blossom in its tone. The only thing I could attribute it to was correcting the bearing. That was when I started putting 2 & 2 together. Could they be related? I believe so.

Pwg


Thanks, makes much sense, especially correcting the DB in the treble with aliquot shims. Wouldn't work in the tenor, of course - the strings are too long. Which tells me that your friend who worked on the SS-B did the same, although at first read it sounded like the DB problem was across the entire scale and the shims were installed across the entire scale to correct the problem, too. That made me doubtful of the narrative...

So I am gathering now that the "oilcanning" as described by you and others is a temporary inversion of crown at the bridge, mostly in the treble, caused by excessive DB in that area. This also causes a temporary loss of crown and DB in the tenor affecting the tone and stability. But the problem could exist without any inversion of crown. Careful measurement in either case would surely show DB in the treble.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/29/19 07:03 PM
I can't seem to post a message. Don't know why.

Pwg
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 11/29/19 07:05 PM
Okay, well that one went through. I've attempted several earlier that triggered a "database" error. I'm not fond re-writing substantial posts. I will try again later.

Pwg
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/01/19 05:24 PM
I recently removed a board from a small SS
Prior to removal with strings on and up to pitch there was very slight (almost not measurable) bearing in the treble, everywhere else zero.
There was zero crown on the board - used straight edge to detect.
The board was not inverted, it was as flat as my straight edge.
Now after sitting for a couple months (out of the piano) the board is very inverted - or oil caned.
Scratches head wondering why it didn’t revert and give some positive crown?? Why negative???
My assumption is the board suffered compression set, failed, lost any support capability it may have had and the ribs now dominate the shape of the assembly.
Why flat sawn ribs would move in the opposite direction I could only guess but it does suggest that this sort of design has an undesired effect of working against crown.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/01/19 06:04 PM
Originally Posted by Gene Nelson
I recently removed a board from a small SS
Prior to removal with strings on and up to pitch there was very slight (almost not measurable) bearing in the treble, everywhere else zero.
There was zero crown on the board - used straight edge to detect.
The board was not inverted, it was as flat as my straight edge.
Now after sitting for a couple months (out of the piano) the board is very inverted - or oil caned.
Scratches head wondering why it didn’t revert and give some positive crown?? Why negative???
My assumption is the board suffered compression set, failed, lost any support capability it may have had and the ribs now dominate the shape of the assembly.
Why flat sawn ribs would move in the opposite direction I could only guess but it does suggest that this sort of design has an undesired effect of working against crown.

I’ll add one more bit of data for what it’s worth: the board was removed during hot dry California Sierra Foothills weather and now it’s cold rainy and damp.
I think its a poor assumption. First of all, you have no idea whatsoever if it ever had extreme compression. or much compression at all. And relating to soundboards, Compression set, may just be a theory, otherwise Craig Hair is using damaged material. I remember looking at the numbers of the compression values that it would take to create compression set in spruce, and I recall thinking that it was pretty near impossible. But in tension across the grain Spruce is very weak. Regarding the ribs inverting, i'd be thinking the Bellyman were distracted that day, and installed ribs that were not properly kiln dried.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/01/19 11:39 PM
Compression crowned boards are known to lose crown faster than any other method of crowning.
They all (Every method of crowning) do eventually.
Many times a new piano right from the factory has flat dead areas caused by excessive compression as a result of the crowning process.
I haven’t done the math for a long time but the elastic limit (FPSL) for Sitka vertically cut, across the grain is very low. The compression crowning process can easily reach this limit before the piano is strung.
My assumption is not so poor.
Consider the 1 percent compression limit rule: compressing wood beyond its FPSL will permanately deform it perpendicular to grain.
And the ribs are designed to restrain the board in order to induce crown. There is no bearing load capacity designed into the system.
Once the elastic limit is exceeded, the board has very little resistance to being oilcanned in either direction.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 12/02/19 02:02 AM
Everything Peter is reporting I have experienced as well.
Gene, I just think that the soundboard should be approached acoustically rather than as a structure. A lot gets lost. I've heard many pianos with thick ribs, massive cutoff bars, and many other fancy ideas that claim to add longevity. Which by the way you can't really promise. But their sound is not my cup of tea.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/02/19 03:49 AM
So only compression board designers are concerned with acoustics?
Come on Chris, that’s a bit naive.
Yes, that is correct Gene,
Check out any writings from any Rib crowned proponents and its about structure only. Check your writings for example, check out your last series of statements.

The acoustic reason Rib crowned boards don't have the same acoustic energy as compression boards is because of whats called Mechanical intensification. Every maker of any acoustic instrument takes, or tries to take advantage of that principle. When the arch is along the grain, tension is used, when across the grain, compression is used. When its a carved arch, a soundpost was needed. Rib crowning is a carved arch.

Rib Crowned guys are essentially making "violins without soundposts".

If you have ever witnessed the tuning fork that is attached to a small piece of spruce demo. Then you would have heard the power of mechanical intensification.
Here's a guy improving the sound of his Cigar Banjo using the principle.
https://www.youtube.com/watch?v=KqYRifl9IxA
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/02/19 04:22 PM
So I make violins and banjos and you make oil cans.
I just can’t take you seriously Chris.
You come across like a used car salesman.
Originally Posted by Gene Nelson
So I make violins and banjos and you make oil cans.
I just can’t take you seriously Chris.
You come across like a used car salesman.


Right on cue. When you lose a factual argument, then you resort to name calling. Just like last time. I'll take your snarky "Used Car Salesman " comment as a badge of honor. Thank You.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/02/19 09:38 PM
Originally Posted by Chernobieff Piano
Yes, that is correct Gene,
Check out any writings from any Rib crowned proponents and its about structure only. Check your writings for example, check out your last series of statements.

The acoustic reason Rib crowned boards don't have the same acoustic energy as compression boards is because of whats called Mechanical intensification. Every maker of any acoustic instrument takes, or tries to take advantage of that principle. When the arch is along the grain, tension is used, when across the grain, compression is used. When its a carved arch, a soundpost was needed. Rib crowning is a carved arch.

Rib Crowned guys are essentially making "violins without soundposts".

If you have ever witnessed the tuning fork that is attached to a small piece of spruce demo. Then you would have heard the power of mechanical intensification.


I have to say that I am quite skeptical about what you say in this post. It's interesting to note that Googling ""mechanical intensification" piano" turns up not a thing of which you spoke, so, if every maker of acoustic instruments is using that principal, it must be a secret. Compression crowning increases the stiffness of the soundboard assembly, and so, if a soundboard is equally constructed, but without compression crowning, it will be less stiff, which may result in a reduced quality of sound. I think it's fair to say that one important component of achieving best sound is the stiffness-to-mass ratio of the soundboard as a function of the various positions across the board. No doubt, compression crowning is one way to achieve a desirable result in this regard. However, the idea that it's the only way does not pass the smell test. Also, it has also been conclusively shown, both by calculation and experience, that purely compression-crowned board often do indeed suffer from compression set.

I have been surprised at how weak a piece of sitka spruce soundboard is across the grain--it can be flexed so easily, and its cross-grain strength is also quite low.
[/quote]

I have to say that I am quite skeptical about what you say in this post. It's interesting to note that Googling ""mechanical intensification" piano" turns up not a thing of which you spoke, so, if every maker of acoustic instruments is using that principal, it must be a secret. Compression crowning increases the stiffness of the soundboard assembly, and so, if a soundboard is equally constructed, but without compression crowning, it will be less stiff, which may result in a reduced quality of sound. I think it's fair to say that one important component of achieving best sound is the stiffness-to-mass ratio of the soundboard as a function of the various positions across the board. No doubt, compression crowning is one way to achieve a desirable result in this regard. However, the idea that it's the only way does not pass the smell test. Also, it has also been conclusively shown, both by calculation and experience, that purely compression-crowned board often do indeed suffer from compression set.

I have been surprised at how weak a piece of sitka spruce soundboard is across the grain--it can be flexed so easily, and its cross-grain strength is also quite low.[/quote]

Roy 123,
Something can exist and not be on Google. The acoustic book I studied used the term. If its under another term i'd be interested (Maybe mechanical strain? Or just plain strain?) I did not give you a single cause, but three ways the mechanical phenomena can be achieved.
And what effects of compression study are you referring to that drew that conclusion? Maybe the downbearing was excessive, maybe the piano was near a wood stove for years, maybe the piano soundboard was installed incorrectly. I have a piano in my shop right now that's 60 years old, compression crowned and in near perfect condition. How does that fit in any conclusion? I will be running tests and the numbers on compression and very soon, and see if compression set is even possible in piano soundboards. Of which i am skeptical. The cracks happen when tension occurs, a compression set wouldn't even have to be there at all for the board to crack under certain conditions.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 12:04 AM
Originally Posted by Roy123
Originally Posted by Chernobieff Piano
Yes, that is correct Gene,
Check out any writings from any Rib crowned proponents and its about structure only. Check your writings for example, check out your last series of statements.

The acoustic reason Rib crowned boards don't have the same acoustic energy as compression boards is because of whats called Mechanical intensification. Every maker of any acoustic instrument takes, or tries to take advantage of that principle. When the arch is along the grain, tension is used, when across the grain, compression is used. When its a carved arch, a soundpost was needed. Rib crowning is a carved arch.

Rib Crowned guys are essentially making "violins without soundposts".

If you have ever witnessed the tuning fork that is attached to a small piece of spruce demo. Then you would have heard the power of mechanical intensification.


I have to say that I am quite skeptical about what you say in this post. It's interesting to note that Googling ""mechanical intensification" piano" turns up not a thing of which you spoke, so, if every maker of acoustic instruments is using that principal, it must be a secret. Compression crowning increases the stiffness of the soundboard assembly, and so, if a soundboard is equally constructed, but without compression crowning, it will be less stiff, which may result in a reduced quality of sound. I think it's fair to say that one important component of achieving best sound is the stiffness-to-mass ratio of the soundboard as a function of the various positions across the board. No doubt, compression crowning is one way to achieve a desirable result in this regard. However, the idea that it's the only way does not pass the smell test. Also, it has also been conclusively shown, both by calculation and experience, that purely compression-crowned board often do indeed suffer from compression set.

I have been surprised at how weak a piece of sitka spruce soundboard is across the grain--it can be flexed so easily, and its cross-grain strength is also quite low.


I can give some design criteria that is common to the different soundboard system designs that I know of: Im certain there are more. Ill lean on the radiused system just a bit more.
First, all tone wood has acoustic properties.
Design factors that could be taken into account include:
How fast sound travels through wood, (specise specific) the moisture content of the species causes internal friction, some people consider soundboard resonance to be a good thing but I disagree, how many grains per inch is important, how thick the board is, the string scale hammers and bridge and getting this energy to the soundboard assembly, the impedance of the the entire soundboard, the mass of the entire soundboard, how stiff and flexible the board is, how much crown the board has, the bearing load on the soundboard assembly, how long the backsclae is, high or low tension scale, the position of the bridges especially the bass bridge and low tenor end of the long bridge. Most bass bridges are glued close to the rim making the board stiffer in that area and this is where flexability is needed. Radiused systems may float the bass to relieve this stiffness.
the different types of designs that I'm aware of are:
Radiused rib crowned, compression crowned and the type that depends on the rim of the piano to support crown, and maybe there are others that combine radiused ribs with some compression.
Then there is the string down bearing and how the soundboard assembly is designed to support it.
Its all about making the soundboard move air efficiently.
If its done with careful engineering and craftsmanship the entire compas will be heard with relatively equal power, tone quality and sustain characteristics.
With a radiused system, the stiffness to mass ratio is carefully controlled and stiffness and flexibility is engineered into the system in a gradual gradation from treble to bass. The ribs support the string bearing load as well as become part of the boards response to input energy from the hammer, string bridge.
The board is somewhat stiff at glue up due to the nature of the wood species, the number and placement of the ribs and the bridge and it increases to desired stiffness after being strung and brought up to pitch.
Compression boards have the stiffness and bearing support more in the board itself as the ribs are designed to restrain the board as it swells and crown is induced somewhere on the board. The ribs tend to resist crown because they are flat sawn. Some designers use the piano rim to help keep the crown in these ribs.
Radiused ribbed boards have specific amount of crown (coordinated with the designed string bearing) imposed exactly where the designer wants it and most of the time its possible to have the apex of the radiused rib directly under the bridge so the bridge can move relatively straight up and down as EMC changes and the board expands or contracts. Also, the strength of the rib is designed to flex a known amount under a known load so that the system is never overloaded and always moves within a controlled range.
Compression boards depend on the cellular structure of the soundboard to support the bearing load and possibly some support from the rim if designed that way.
Then there are other things like - are there verticle hitch pins, are there adjustable plate bolts that allow a designer to fine tune the system - typical on a radiused system.
For all designs there are good and bad results. I don't know of any that have been perfected.
I truly respect all rebuilders that get involved with this sort of work with the desire to create a better musical instrument.
Maybe one day we will have a perfect piano, I kind of doubt it.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 12/03/19 01:23 AM
I believe that, though a CC soundboard does in fact enhance the sound, from a manufacturing standpoint, since the process basically violates established principles of longevity in woodworking, the design is recognized to last roughly 30-40 years. Some will last longer under super ideal conditions, others shorter if abused and neglected, but on average 30-40 years seems to me to be the time when fatigue, stress, environmental changes, etc make the assembly "fail" in the sense of no longer being able to function at anywhere near peak capacity. Yes, it "works" but not like it used to (assuming of course it was well made to begin with).

Planned obsolescence?...I think not. Simply recognition of what wood can take and for how long.

Pwg
Posted By: Ed Foote Re: "Oilcanning" Soundboard Skeptic - 12/03/19 02:16 AM
Originally Posted by P W Grey
I believe that, though a CC soundboard does in fact enhance the sound, from a manufacturing standpoint, since the process basically violates established principles of longevity in woodworking, the design is recognized to last roughly 30-40 years. Some will last longer under super ideal conditions, others shorter if abused and neglected, but on average 30-40 years seems to me to be the time when fatigue, stress, environmental changes, etc make the assembly "fail" in the sense of no longer being able to function at anywhere near peak capacity. Yes, it "works" but not like it used to (assuming of course it was well made to begin with).
g


Greetings,
Hmm, logic and engineering can only go so far. Big data often usurps the apparently evident, and I have to say, the big data on piano soundboards over the last 150 years has demonstrated a large percentage of pianists are attracted to whatever Steinway has going on in that soundboard of theirs. Smoke and mirrors won't keep a tonal fantasy alive forever, there has to be some response, and in my career, I seldom find a more responsive sounding structure than what came out of New York. Not consistent, but the best of the best pianos I have seen had that double S on the fallboard. .

As to building a soundboard that will "last" forever, it is simple, just make everything stronger (and heavier). However, tonal response and longevity are often inversely related and I think the maximum performance from a board is attained when it is sufficiently stressed. This means that the CC soundboard is a "non-durable" part of the piano, just like hammers and dampers,(and to a lesser extent blocks, but I have seen numerous blocks that were in far better condition than the board they were married to.).
I once had a BMW motorcycle with drum brakes. After 120,000 miles, the shoes were still in good condition, but they never performed as well as the softer recovering I had done. The softer stuff made a huge difference in stopping distances, but were worn out in 30,000 miles. I like the shorter-lived version better because it performed better.

Steinway is building boards for maximum performance, not maximum longevity. I have a 1937 M right now that will easily respond as well as a new one, ( or better), and I have seen 10 year old boards in these pianos that were flat and hollow sounding, no matter what I did with the hammers. The CC approach requires great expertise in setting the bearing pressure, and if done poorly, the board will either collapse too soon, or never be stressed enough to speak. If done right, I think they out run most anything else I have seen.
Regards,
Gene,
Thank you for the explanation.
The way you describe how compression crowned boards work i would say is not accurate. The way you describe it, it would be prone to failure. A flat rib glued on a flat panel then glued in the piano would have a difficult time crowning. Your description makes me think that that is your assumption. I use a radiused caul and the soundboard already has a healthy crown (60,55,50ft) before its glued in, simply by the "shifted" rib/panel glue joints. Then the "controlled"
compression builds to create the highest stiffness to weight ratio. At least that's my rough guideline.

Your description of the RC&S system makes me think of what the grain is doing. After the rib is loaded isn't the grain inverted? An inverted crown with a curve cut on top? There's nothing wrong with that. Julius Bauer used ribs on both sides, i believe they were inverted crowned. I can't comment on their operating principle because I haven'y had one to dissect Yet.

So how do you measure the stiffness to weight ratio in your boards? My understanding is that with so many factors it not really possible with any degree of accuracy.
Ed Foote,
That's how i see it, but you said it better.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 03:35 AM
“ Compression boards have the stiffness and bearing support more in the board itself as the ribs are designed to restrain the board as it swells and crown is induced somewhere on the board. The ribs tend to resist crown because they are flat sawn.”

That was my statement but I suppose that I need to explain the drying process prior to gluing on the ribs? Followed by exposure to higher moisture?
I assumed that designers understood the compression crowing process but I guess not.
And yes, they are prone to failure.

Radiused ribs tend to have exposed end grain along the radius. But inverted? You may be able to argue that but the FSPL has not been exceeded like the dead inverted compression board that is in my shop. The radiused ribs retain their radius just fine and continue to do what they are designed to do for a very long time.
Your mixing words and design concepts.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 03:43 AM
As for the Steinway sound, I’d give more credit to the rim as opposed to the soundboard.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 04:37 AM
As for stiffness to mass, if I were a physicist I may be able to develop a formula but it’s doubtful.
Mass includes the bridge and everything on it like pins and screws and buttons even finish, the board itself, the ribs, the finish on the board,
The stiffness; the panel itself has a small amount if it has not experienced compression beyond its elastic limit, the size shape of the bridge and what wood it’s made of, the thickness and grain spacing and grain angle of the board in relation to bridge placement, string bearing pressure, available crown and how it’s supported and how much of it is used up under load, the number and location of ribs and if the rim is rock solid laminated maple it may contribute. Another may be how the ribs are anchored, not all are notched into the rim.
You just need to be aware of what contributes stiffness as the assembly goes together.
Mass is easier.
Gene you claimed that,
“With a radiused system, the stiffness to mass ratio is carefully controlled and stiffness and flexibility is engineered into the system in a gradual gradation from treble to bass.”

I then ask you,
Gene, How do you measure the stiffness to weight ratio?

Your response was,
“If I were a physicist, I may be able to develop a formula, but it’s doubtful.

If you have no stiffness to weight formula, then how do you carefully control it?

Thanks
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 02:08 PM
You can re-read my last post but I’ll spell it out for you:
Purchase a board of known thickness and grain angle.
Don’t expose it to excessive compressive forces that destroys its elasticity.
Control the EMC when gluing in ribs.
Design the rib system.
Redesign the scale.
Build a new bridge to conform to the new scale.
Set bearing.
String it up and bring it to pitch.
Sometimes weigh components.
Not necessarily in that order.
And it all gets placed glued screwed together and installed carefully
Are you mixing words again?
Careful does dot imply formula.
What’s your motive Chris?
Have you told the OP what your idea of an oil canned board is yet?

I don't think you understood the question Gene.

You said the Stiffness to Mass ratio is carefully controlled. You then went on to give definitions of what mass is, and then what stiffness is. But the question is- How do you carefully control the ratio between the two? As you claimed you can do.
Thanks
-Chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 03:57 PM
And I don’t think you understood my questions.

I have a good idea of what components of the soundboard system contribute to stiffness and place them accordingly/carefully. Mass is easy.

Now tell the op what is your idea of an oil canned board?

What is your motive?
I know you will never do any type of RCS type work because you have previously informed me that your techniques are superior.
That’s why I have difficulty taking you seriously, it’s like you have an unnatural need to prove me wrong and sell your product, analogous to a used car salesman.
Communication with you is difficult, sorry.
If you sincerely want to learn RCS design concepts there are people that teach at conventions and shops that you can apprentice at, like I did.

Gene,
I just asked a simple question. So I get it, you're taking educated guesses.

It doesn't matter to me what oil canning is or isn't because I replace old damaged boards with new ones.

And it looks like you're back to name calling again.

What a pleasure.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 05:44 PM
Your question was not simple. It had very selfish motive.
If you dont care about oil canning, why particiapte in this thread?
I think your mind reading skills are off Gene..

I've been collecting data for 4 years on soundboard structures with an emphasis on measuring soundboard stiffness. I created an algorithm and came up with a working Constant (K) that produces a pretty reliable curve. Especially useful when comparing one board to another and to circumvent any future mishaps.. Even a well known piano rebuilder near Modesto was impressed. I asked because there were formidable challenges in the process. I was wondering how others surmounted the challenges.

That's why i asked the question.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/03/19 07:11 PM
Well your way ahead of me
What I told you is how I quantify stiffness, as I said, I don’t have a formula, just knowledge of what components provide stiffness and where to put them and how to dimension them.

Maybe if i meet you person to person one day I won’t need to read minds and may think differently about you.

But again, this thread was about oil canned boards
It went sideways because you did don’t like my explanation.

Maybe publish your K constant in the Journal when it’s ready.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/03/19 08:58 PM
Here are some quotes from Del Fandrich that were taken from several of his posts in Pianoworld. I could have included many more, but I think these suffice--

"The peak compressive forces that can build up in a soundboard panel that is crowned this way is between 1% and 2% depending on the specific wood samples and the atmosphere the soundboard assembly is exposed to.

"It is generally accepted within the woodworking industry that to avoid rapid compression stress failure wood should not be under any more than 1% compression (perpendicular-to-grain) for even relatively short periods of time. Significant long-term compression set will occur at much lower levels of compression than this."



"Yes, compression can and does damage wood. The most extreme and visually dramatic occurrence of this damage in the piano soundboard are the compression ridges that often show up in soundboard panels crowned in this way. As the name implies internal compression is literally forcing the latewood layers up or down as the earlywood fibers fail in shear as the force from internal compression becomes greater than they can withstand.

"Even without exhibiting this kind of dramatic failure a wood member held in cross-grain compression over a period of time will physically change shape. In other words a panel that is held in compression across grain will gradually lose some of its overall width. If you were at all inclined toward experimentation I would suggest the following:

"Cut a 250 mm long (i.e., with the grain) by 1025 mm wide (across-grain) panel of nice new spruce. Dry this panel to 4% moisture content. (You’ll have to determine this by weighing samples, wood moisture content meters do not read accurately below 6%.) With the panel at 4% quickly cut it to exactly 1,000 mm and put it into a prepared frame that will hold it flat but which will not put any pressure on it at 1,000 mm but which will not allow it to expand beyond that initial 1,000 mm. Now set the whole thing aside in a normal atmosphere for a year.

"When you take your panel out of the frame and dry it back down to 4% moisture content you will find it is no longer 1,000 mm wide but somewhat less that that. Just how much less will depend on the specific characteristics of the wood you used and the extent of the humidity swings to which it has been exposed. If you leave it in your frame long enough you will eventually see it actually coming away from the ends during moderately dry periods. This is the effect of compression-set.

"This is the piano version of the illustration Hoadley gives on page 114 of his book, Understanding Wood. This illustration shows how constrained wood samples are damaged through the mechanism of compression-set after being exposed to varying amounts of humidity. The experiment I've described above is roughly equilivent to the middle sample. What has happened to the sample on the left is exactly the same as what happens to a compression-crowned soundboard panel over time. The soundboard panel is physically constrained by being solidly glued to all those perpendicular-to-grain ribs on one side of the panel. Those ribs don’t allow the panel to freely expand and the resulting stress-interface between the compressed (trying to expand) soundboard panel and the ribs forms the crown. Without that compression there is no crown.

"A free piece of wood like a soundboard panel (or the sample on the right in Hoadley’s illustration) will not develop any internal compression or tension due to changes in humidity. It will simply expand or contract depending on whether it is absorbing or desorbing moisture. It is only when the wood is constrained and not allowed to move that it will develop either internal compression or tension.

"Standard woodworking practice calls for wood to be at a minimum of 7% moisture content at glue up. To go below this can lead to starved glue joints as the wood will very readily draw the glue solvent (usually water) out of the glue. This is well above the 4% moisture content called for in the process of gluing up a compression-crowned soundboard assembly.

"Gluing up a soundboard panel at the 4% moisture content required to end up with a compression-crowned soundboard assembly is abnormal to the woodworking industry. Several of the wood technologists I have consulted on the subject expressed mild shock and something bordering on disbelief when the process was explained to them.

"Like it or not the soundboard panel in a compression-crowned soundboard assembly is under long-term compression and it remains under compression until compression-set has relieved that compression by physically altering the shape of the wood fibers. It is a gradual but certain process."


"The peak compressive forces that can build up in a soundboard panel that is crowned this way is between 1% and 2% depending on the specific wood samples and the atmosphere the soundboard assembly is exposed to.

"It is generally accepted within the woodworking industry that to avoid rapid compression stress failure wood should not be under any more than 1% compression (perpendicular-to-grain) for even relatively short periods of time. Significant long-term compression set will occur at much lower levels of compression than this."



"A compression ridge is ”by definition” damage to the wood fibers in the affected area.

"In the short term compression damage develops when wood fibers are subjected to compression stress greater than their fiber stress proportional limit, or FSPL. For Sitka spruce (in the perpendicular-to-grain axis) this is about 550 to 600 lbs per square inch. If a piece of Sitka spruce is loaded to, or much beyond, this point some fiber failure will be immediate. It is unlikely that anything approaching this amount of compression will be placed on a soundboard panel either during construction or in use.

"In the long term, however, fiber damage can develop when a piece of wood is forced into compression, again in the perpendicular-to-grain axis, by more than about 1%; an amount commonly found in certain types of soundboard construction. How much actual stress will be developed with this amount of compression is unpredictable but it will be well below the wood’s FSPL. But wood is also affected by a time dependent deformation known as creep. Some of the stress in a piece of wood subjected to long-term perpendicular-to-grain compression will dissipate over time. How long is “long term” depends on many variables but can be anywhere from a couple of weeks to some years.

"The presence of compression ridges in a piano soundboard usually indicates that its crown was developed by gluing a very dry wood panel to flat ribs. (It is rare to find compression ridges in soundboard systems that derive their crown from a pre-shaped rib.) As the soundboard panel absorbs moisture in a normal atmosphere it is physically restrained by the perpendicular-to-grain ribs. As a stress interface builds between the soundboard panel and the ribs a curve, or “crown,” is developed. These soundboard systems depend on some amount of continuous internal compression to maintain that stress interface and, hence, their crown. Over time some of that initial compression dissipates due to long-term creep and the amount of crown built into the soundboard decreases.

"Whether or not the presence of one or more compression ridges is affecting the tone of the piano depends on many variables, none of which is predictable with any accuracy. What is certain is that the stress interface between the strings and the soundboard that was initially built into the piano has changed. And it will go on changing—though at an ever-decreasing rate—over the life of the piano. Many pianos with clearly visible compression ridges sound just fine and they can go on sounding just fine for very long periods of time. Others begin showing signs of tonal degradation within months of their manufacture.

"If I am evaluating a used piano having a soundboard panel that has developed compression ridges I will pay particular attention to the decay rate through the upper third of the scale. This is where soundboard deterioration will be most noticeable. If the tone here is abnormally percussive and falls off rapidly the acoustical condition of the soundboard will certainly be suspect; it will be worth some time tracking down the cause of that decay rate. Especially if the piano is relatively new. If, however, the piano is, say, ten years old and the decay rate is normal through this area I’ll probably give the soundboard system a clean bill of health in spite of the presence of a few compression ridges.

"There is much good information on the various strength characteristics of wood can be found in The Wood Handbook, a publication of the Forest Products Lab (it's a free download from their website). See especially Chapter 4 (Mechanical Properties of Wood). Another good reference is Understanding Wood by R. Bruce Hoadley. Again, see Chapter 4 (Strength of Wood).
"
Posted By: kpembrook Re: "Oilcanning" Soundboard Skeptic - 12/03/19 11:34 PM
The Del Fandrich quotes are worthwhile. But they are not fully descriptive of what actually happens with a ribbed-up soundboard panel. Specifically....

The soundboard is constrained on ONLY ONE SIDE. Of course everyone -- including certainly Del -- knows that. But -- like so many things in the piano world, people are taking principles and applying the principle without corresponding rigorous experimentation -- or even adaptation to piano applications.

What this means is that one side of the board IS NOT CONSTRAINED. In fact that is where the power for crown comes from. So, the side that is not constrained will not necessarily suffer the cellular destruction that the constrained side does. Cellular destruction will be transitional throughout the thickness of the board. Has anybody ever looked at the cellular structure of soundboard wood to see how cellular crushing is distributed through the thickness of the board? I think not. Or, at least, if they have they haven't told me. laugh Rather, people throw around theories and general principles (which may possibly even be valid).

Which gets to the whole idea of crown and what it's really about...
Crown was never identified as an ideal principle that needed to happen and was sought after as some holy grail by the beginning piano industry. Rather it's an interesting but fundamentally irrelevant phenomenon that occurs when there is dynamic tension in a particular wooden structure. The same thing happens when an archery bow is strung up. Also, when a string is pulled to tension or a drumhead stretched across the drum shell. This is what is significant:
Dynamic tension promotes vibration.
This may be one element of the Steinway sound because the rim itself is in dynamic tension.

So, achieving the appearance of crown without the presence of dynamic tension is missing the point. Soundboards are not floors -- whose design concept is to "support" a certain amount of load. Of course, it's true that there is (or should be) pressure of the strings against the soundboard and that can be considered a "load". But that's not the point. It's not how "solid" the soundboard "floor" is but rather, how "bouncy" it is. There are engineering tables for load bearing qualities of beams. But I'm not aware of tables that have been calculated for "bounciness" of beams. In any event, the enthusiasm for an overly facile application of stock engineering data is largely misplaced in my opinion.

Thus, at this point, we don't know as much as we may sometimes think we do. I think this situation is similar to the whole discussion about "touchweight" (a completely wrongheaded concept). We are like the astronomers of the Middle Ages who could predict planetary movements sometimes but not always. At this point, we don't fully have the rigorous science that would be nice if the piano industry had the financial resources for experimentation that some other industries enjoy.

By way of personal disclosure, I learned soundboard construction from the Trefz family of Philadelphia. I do a combination of natural crown and "cut crown" . But, I understand that the "cut crown" functions as nothing more than a particular way of tapering rib thickness (which may or may not promote flexibility) rather than somehow achieving a shape that magically causes good tone.

Dels post has two critical errors,

The first is that the soundboard is not in a constrained immovable frame that restricts its movement. The soundboard can breathe, that's why your tuning is affected at seasonal changes.


The second is performance as was discussed earlier. He's only presenting a biased structural argument. An analogy would be a drag race. You can have hard rubber tires or you can have soft tires. Notice the choice is the soft tires that have to be replace after a single race. Del is in essence arguing about the flaws of the soft tires.Structurally, you can argue how much longer the hard tires will last, but the point is to get down the track fast.

The purpose of soundboards is to give the piano a full cultured operatic type voice.

-chris
Posted By: kpembrook Re: "Oilcanning" Soundboard Skeptic - 12/04/19 02:08 AM
Originally Posted by Chernobieff Piano
Dels post has two critical errors,

The first is that the soundboard is not in a constrained immovable frame that restricts its movement. The soundboard can breathe, that's why your tuning is affected at seasonal changes.
<snip>
-chris


Well, what Del is describing is similar to the soundboard being glued into the rim. Since the soundboard can't expand as it normally, does, it bellies upward. But my point was that it is constricted on only one side -- so it does have substantial freedom of movement which should reduce the impact of compression.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 12/04/19 03:54 AM
Crown functions to allow for the soundboard to react to humidity changes WITHOUT splitting easily. It is an expansion joint.

Soundboards bellied at too high humidity will split quicker in dry conditions than ones bellied dryer. This is because of the weak cross grain of the wood.

Cut for crown ribs can actually make it easier for a board to crack in dry times since they resist allowing the board to flatten as much.

I have dozens of pianos bellied in the 4% EMC range, (by this I mean it has dropped below 5%), that I see year after year and none have any cracks in over 30 years. They all sound rich with excellent sustain. Some do sound better than others, but after all wood does vary and we only can test for so much in one lifetime. And all the Steinway's sound like Steinway's. I can't say that for all the other rebuilders who replace soundboards that I have sampled.
Posted By: pyropaul Re: "Oilcanning" Soundboard Skeptic - 12/04/19 04:17 PM
I wonder how the Paulello soundboards, that have essentially no crown, hold up to seasonal changes of humidity.

Paul.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 12/04/19 06:02 PM
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/04/19 06:15 PM
I'd like to correct a few things. First, soundboards are not constrained only on one side. That would be the case if the ribs had no stiffness against bending. That is not the case, and the ribs are far stiffer than the board. Even if the ribs had no stiffness, that leaves one side of the board under full compressions. To say that the soundboard can breathe ignores the constraint caused principally by the ribs, and secondarily by the rim.

While it's true that some compression-crowned boards can last a long time, other examples fail quickly. Of course, it's also true than some builders may not dry their panels so drastically, and these boards, although compression crowned, would be under lower compressive forces.

If you don't mind an anecdote, I once inspected a Petrof grand of perhaps 10 or so years of age. It looked pristine, but its board was full of compression ridges--it seemed like they were at almost every board-to-board joint. It's hard to imagine such a board did not have serious compression set. FWIW, the piano didn't sound particularly good, either.

Finally, those who take Del's writings so lightly fail to remember the years of practical experience he had. No doubt, his opinions were backed up by his real-world observations.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 12/04/19 11:07 PM
Del has even questioned whether crown (in and of itself) is in fact necessary for optimum performance, but rather stiffness alone possibly a more important factor.

Personally I believe (though impossible to prove) that forced crowning came about as a way of controlling what COULD happen to the soundboard (reverse crowning...loss of bearing, etc) once it started getting exposed to the variabilities of humidity and dryness. And, as a side benefit of doing this they found that there was an overall improvement in the vibrational characteristics of the more successful ones. As a result they devised methods to consistently create crowned boards to reasonably specific specs. IOW it was sort of an accident.

This is just a theory of course (and unprovable in any way at present), however no one presently, or in writing seems to know when, where, or who made the first crowned soundboard, or did so consistently. There is no info on this. Can anyone dispute this with some facts? I'm open to it. I have asked around and so far the answer has been "IDK".

The fact (as mentioned) that CF soundboards have no, and need no, crown is strong circumstantial evidence that it is STIFFNESS coupled with lightness...not crowning (in and of itself) that creates the qualities we want. It is likely that if they had such a material back then (stiff and light together) they would have used it. Instead they figured out the best way they could to make a light material stiffer without adding too much weight. Thus the ribbed...and ribbed and crowned soundboard.

Just a theory...fire away!

Pwg
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/04/19 11:37 PM
I
Originally Posted by P W Grey
Del has even questioned whether crown (in and of itself) is in fact necessary for optimum performance, but rather stiffness alone possibly a more important factor.

Personally I believe (though impossible to prove) that forced crowning came about as a way of controlling what COULD happen to the soundboard (reverse crowning...loss of bearing, etc) once it started getting exposed to the variabilities of humidity and dryness. And, as a side benefit of doing this they found that there was an overall improvement in the vibrational characteristics of the more successful ones. As a result they devised methods to consistently create crowned boards to reasonably specific specs. IOW it was sort of an accident.

This is just a theory of course (and unprovable in any way at present), however no one presently, or in writing seems to know when, where, or who made the first crowned soundboard, or did so consistently. There is no info on this. Can anyone dispute this with some facts? I'm open to it. I have asked around and so far the answer has been "IDK".

The fact (as mentioned) that CF soundboards have no, and need no, crown is strong circumstantial evidence that it is STIFFNESS coupled with lightness...not crowning (in and of itself) that creates the qualities we want. It is likely that if they had such a material back then (stiff and light together) they would have used it. Instead they figured out the best way they could to make a light material stiffer without adding too much weight. Thus the ribbed...and ribbed and crowned soundboard.

Just a theory...fire away!

Pwg


I’ll follow with a question: comparing two unloaded but crowned soundboards, both Sitka and ribbed, one compression crowned the other radiused with ribs, which one has more stiffness??

I can relate experience working with 3 concert instruments two SSd’s and a B
All three have zero string bearing in the 5th 6th octave ares, the B a bit more extensive and all three lack sustain compared with the rest of the piano/s compass and all 3 have no measurable crown in the affected area.
Voicing gave a presence so they are noticeable as having power at the expense of getting hammers so hard they border on buzzing or that excessive bright sound when playing FF.
I’ve tried many things over the years to get some sustain so I can voice a bit different and it is the simplest thing that helped. Not tension resonator. Ribblett helped a little adding stiffness. But what gave the added sustain needed to blend these areas with the rest of the compass was a simple spring placed between rib and board.
So did the spring add stiffness or maybe a very small amount of crown (could not measure any)
But spring back against the force of string bearing happened and I got results.
One interesting bit of info was when I restrung one of the D’s earlier this year - slight crown appeared in the affected area after strings removed. So there was some stiffness and impedance even if lacking power and sustain
After studying many photographs of soundboards( and the ribbing) of Ruckers, Cristofori, and Silbermann. I found that Silbermann was starting to use compression as a means of adding mechanical strain. Silbermann made many copies of Cristofori type pianos inventing improvements along the way. I found one photo in which Silbermann changed the rib orientation from perpendicular to the bridge (which puts the ribs at a varying angle to the grain) to 90 degrees to the grain. When building instruments every day of the year, it wouldn't take long to figure out that the instruments made in the dry winter sound better in the humid summer.
Conjecture is just that, but looking and studying their work says a lot more.
-chris
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 12/05/19 03:57 AM
I have heard several pianos that I was told Del had installed a new board in. I never cared for the sound in the least. Several were Steinway's and they did not sound like what I expect one to sound like.

When he lectures, he says many things I agree with. But his work and I disagree.

The impedance modeling he explains is not in the least bit useful to my work. I above all prize utility.

I have tried and heard the valve spring under the bridge trick and I never found it caused an improvement and in fact found in most cases removing them improved the sound.

I have found and proven the "killer" octave is much better addressed by reducing hammer mass, idealizing pivot termination, setting proper strike point, having tight bridge pins, having maple bridge caps that are properly made, inline string spacing, and reducing the ability of the bridge to rock to longitudinal mode energy can make a treble blossom.

I have seen several quite new European grands that have splits in the board. There was no sign of compression ridges in them like you often see traces of in Steinway style boards. I suspect they split because they were made at too high RH and this left them highly vulnerable when exposed to humidity in the low 30% range. Which we do experience indoors in the Pacific Northwest sometimes during winter cold snaps. I have to think a few Nebraska winters would destroy them unless the room/piano was humidified to not go below 40% RH..
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/05/19 04:36 AM
Well, strike point, friction, tight bridge pins, optimum action geometry and regulation are a given for concert
Instrument and maybe the spring and riblett worked because I don’t reduce hammer mass. Never cared for the thin sound or feel of the action with light hammers.
Some of the best artists on the planet have complemented my pianos.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/05/19 04:50 AM
Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile

Originally Posted by UnrightTooner
Sorry to ignore you fine folks. Been at deer camp.

So... Can we put aside the possible causes of "oilcanning" and the the likelihood of some soundboard construction methods to have "oilcanning" for the time being and see if there is a consensus on the definition? To me, "oilcanning" is a mechanical phenomena where the spring rate of an object suddenly becomes less as pressure is increased, but is not permanent. That is, it is not beyond a material's elastic limit. I don't believe this can happen with a soundboard and I don't think any of the fine posts say so.

Those of you that want to provide a clear definition may want to explain what indicates "oilcanning" while still strung, and after unstringing. Everything else being discussed is very valuable and I look forward to it continuing, just not sure we all have the same picture of an "oilcanned" soundboard. smile


I thought I gave a reasonable idea of what I thought could oil can a board. Likely not the clear definition desired but it’s my opinion. Anyone else?

Wow
Don’t know how the duplicates happened
Sorry
Posted By: kpembrook Re: "Oilcanning" Soundboard Skeptic - 12/05/19 06:13 AM
Quote
. But what gave the added sustain needed to blend these areas with the rest of the compass was a simple spring placed between rib and board.
So did the spring add stiffness or maybe a very small amount of crown (could not measure any)
But spring back against the force of string bearing happened and I got results.
One interesting bit of info was when I restrung one of the D’s earlier this year - slight crown appeared in the affected area after strings removed. So there was some stiffness and impedance even if lacking power and sustain


I've done the automotive valve spring thing. Seemed to help.

But a compressed spring is a dynamically opposed force -- which is what I said promotes good tone -- rather than some mystical shape in and of itself.
So how does a 100 year old RCS board age?
I may have an example. A 1927 Vose and Sons Grand came into my shop and it was the earliest example of an RCS soundboard system that I have seen. Same rib scales as seen today with a cut off bar keeping ribs to no longer than 37"., and the typical cut crown carved on top of the rib and the bottom of the ribs were flat and or inverted. All the same ideas used by some "rebuilders" today. The soundboard had about 8 cracks in it. Since it would be "impossible" to have acquired compression set, then why so many cracks?

Here's a pic:
http://forum.pianoworld.com//ubbthreads.php/galleries/2919952.html#Post2919952

Here's how it sounded"

https://www.youtube.com/watch?v=YmES7rTRNGU
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/05/19 03:39 PM
Originally Posted by kpembrook
Quote
. But what gave the added sustain needed to blend these areas with the rest of the compass was a simple spring placed between rib and board.
So did the spring add stiffness or maybe a very small amount of crown (could not measure any)
But spring back against the force of string bearing happened and I got results.
One interesting bit of info was when I restrung one of the D’s earlier this year - slight crown appeared in the affected area after strings removed. So there was some stiffness and impedance even if lacking power and sustain


I've done the automotive valve spring thing. Seemed to help.

But a compressed spring is a dynamically opposed force -- which is what I said promotes good tone -- rather than some mystical shape in and of itself.


Before I tried the spring I tried (and failed) using powerful rare earth magnets trying to take advantage of their repulsive forces. A fun effort however.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/05/19 04:01 PM
Hello, we follow these conversations, and Craig Hair was mentioned. And something about the soundboards we re-crown,using "damaged wood" , Hah!...You mean you don't know something. Well I am open to questioning there.???? Yes these old SB's are distorted slightly from when new and now it is super ideal for tone production, "more bang for the buck", and very stable.

Oil can silly talk?. The wood shrinks down in size. A guy near here in Conn. Chris Robinson referred to it as "inverted-crown".
When you UN-string and the bridge is lower than the string plane, it is the (boards getting narrower), often with enough force to tear the ribs apart,"tensile force" collapsing everything. Kaput-ski, And I will say it again, we have never found CRUSHED cells.

Every piano person should have a crown profile tool, like the one in the U Tube "Sound Board walk around 1+2 videos, Very Very useful.
It shows for sure where the curves are, and one must have curves!

Richard Blais.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/05/19 04:06 PM
Oh yes about Bruce Hoadley, the wood guy, he knows nothing about old, piano wood. I have had him on the phone about this some years ago now, many years ago.
R Blais.
Kudos to McMorrow on the expansion joint reference.
I just watched an engineering video on the subject and it was very educational.

Here's a link: https://www.youtube.com/watch?time_continue=37&v=pH7VfJDq7f4&feature=emb_logo

Of particular interest was the bridge model. With ends free the model moves fore and aft. With the ends fixed, crowning happens. Exactly the same process with soundboards and moisture content. So with a bad install ( soundboard glued in with high moisture content) there was most likely an insufficient expansion joint.
Hence the cracks and the most likely explanation for their cause.
-chris.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/05/19 06:02 PM
Comment 1: I’ll follow with a question: comparing two unloaded but crowned soundboards, both Sitka and ribbed, one compression crowned the other radiused with ribs, which one has more stiffness??"

Comment 2: "When you UN-string and the bridge is lower than the string plane, it is the (boards getting narrower), often with enough force to tear the ribs apart,"tensile force" collapsing everything. Kaput-ski, And I will say it again, we have never found CRUSHED cells."

Comment 3: "I may have an example. A 1927 Vose and Sons Grand came into my shop and it was the earliest example of an RCS soundboard system that I have seen. ... The soundboard had about 8 cracks in it. Since it would be "impossible" to have acquired compression set, then why so many cracks?"

Comment 4: "I have heard several pianos that I was told Del had installed a new board in. I never cared for the sound in the least. Several were Steinway's and they did not sound like what I expect one to sound like. "

Reply to Comment 1: You can't tell, because stiffness varies significantly with rib aspect ratio, thickness, and spacing. One can always dial in various degrees of stiffness by changing various design elements.

Reply to Comment 2: How would you know there weren't crushed cells? To judge that would require examination of various areas of the board under a microscope. One would also need specific knowledge as to how to identify crushed cells. Additionally, compression set may not create violently crushed cells, and therefore the damage may not be readily identifiable to the untrained eye.

Reply to Comment 3: Given that the panel is constrained by the ribs, the possibility of cracking exists as a result of humidity swings. In a RC board, given that the stiffness is not derived from cross-grain stress in the panel, the affect of soundboard cracks should be far less deleterious.

Reply to Comment 4: I don't doubt what you heard, but it's important not to go from the specific from the general, i.e., just because one doesn't like the sound of Del's RC boards doesn't mean other RC boards designed with different parameters might not sound wonderful.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/05/19 06:32 PM
That is why the space in between railroad tracks?????, they make louder clickity clacks on cold days.
Man,, this response is a bit much, so much. And yes Vose had very high crown, with ribs shaped round, and they never were considered superior, we have had some of them. They made a medium-inexpensive piano, nothing special.
We find this deformation, "compression set" on the under side, only. When we re-join a panel, they are slightly curved on the bottom, making it difficult to join them, we actually use a gum resin in alcohol treating the wood to deal with this, it is not possible without it, after years of experiments. Expansion co-efficien of steeel is not good example.

R Blais.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/05/19 06:52 PM
Originally Posted by Roy123
Comment 1: I’ll follow with a question: comparing two unloaded but crowned soundboards, both Sitka and ribbed, one compression crowned the other radiused with ribs, which one has more stiffness??"

Comment 2: "When you UN-string and the bridge is lower than the string plane, it is the (boards getting narrower), often with enough force to tear the ribs apart,"tensile force" collapsing everything. Kaput-ski, And I will say it again, we have never found CRUSHED cells."

Comment 3: "I may have an example. A 1927 Vose and Sons Grand came into my shop and it was the earliest example of an RCS soundboard system that I have seen. ... The soundboard had about 8 cracks in it. Since it would be "impossible" to have acquired compression set, then why so many cracks?"

Comment 4: "I have heard several pianos that I was told Del had installed a new board in. I never cared for the sound in the least. Several were Steinway's and they did not sound like what I expect one to sound like. "

Reply to Comment 1: You can't tell, because stiffness varies significantly with rib aspect ratio, thickness, and spacing. One can always dial in various degrees of stiffness by changing various design elements.

Reply to Comment 2: How would you know there weren't crushed cells? To judge that would require examination of various areas of the board under a microscope. One would also need specific knowledge as to how to identify crushed cells. Additionally, compression set may not create violently crushed cells, and therefore the damage may not be readily identifiable to the untrained eye.

Reply to Comment 3: Given that the panel is constrained by the ribs, the possibility of cracking exists as a result of humidity swings. In a RC board, given that the stiffness is not derived from cross-grain stress in the panel, the affect of soundboard cracks should be far less deleterious.

Reply to Comment 4: I don't doubt what you heard, but it's important not to go from the specific from the general, i.e., just because one doesn't like the sound of Del's RC boards doesn't mean other RC boards designed with different parameters might not sound wonderful.


Thank you for addressing these and as for #1 I would think the panels described both have the same stiffness and their differences would manifest after they are loaded with the string bearing.
But I can’t prove it.
I was hoping Chris May have an idea using his K constant??
I did a study 2 years ago and made a chart of comparison. Using a set of parameters and then using the same on every board and make.

http://forum.pianoworld.com/ubbthre...ndboard-stiffness-study.html#Post2920266

To explain the numbers.

I make my boards at 300, the same K values as the Baldwin L, and a 7' Weber. and a Charles Stieff Upright in which I loved their balance sounds. I went by sound first, and only later learned their stiffness K was identical.

Lower, the boards start having too much of a hollow open sounding bass for me.
Higher, the boards start getting stiffer but at the same time they are adding Mass. The pianos that are over 500 were horrible sounding to me.

Another simple way to measure stiffness is to use frequency. I use a chladni test to find the fundamental frequency of a board. The higher the frequency, the stiffer the board. I'm still collecting data of different boards and their frequencies using Chladni. A couple are on my youtube channel.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/06/19 12:40 AM
Considering and in regard to my question about unloaded soundboards that are crowned different and your K value:
Are you certain you are quantifying stiffness? Especially that Chalandi (sorry if misspelled) test.
For the sake of argument I’d say your capturing more like impedance of the wave, or elasticity times mass?? Maybe I’m splitting hairs.
I still think that both boards have the same stiffness when unloaded.
That is if the materials are the same species.
If I’m right, quantifying stiffness seems very difficult, on paper anyway.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 12/07/19 01:22 AM
As regards ROY123's response to my experience he notes above as "comment 4":

The expense of trying a method/model that changes the practices I was taught in soundboard making is too much risk for me to bear. And I do more experimenting than most piano makers in design details. I try to choose my battles wisely. Since I have had no problems with the way I make soundboards, and I dislike what I hear in the RC boards I have heard, I find it more productive to solve issues such as string termination problems, duplex noises, longitudinal mode issues, etc.

Roy if course correct, I have not proven my boards are superior, and the RC proponents have not proven their superiority.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 12/07/19 01:34 AM
I also find using modeling that explores how L-mode moves from the strings into the structure solves many issues that are recognized as faults by pianists and technicians.

The claims that CC boards are responsible for the "killer" octave problem are not proven at all. I have taken pianos that technicians have claimed have soundboard issues and solved the problems without replacing the board.

These techs were probably influenced by the impedance model Del and others promote. One term missing from the usual presentation of impedance modeling for pianos is the influence of the unison coupling. It changes everything when you understand how this works in pianos.
I'm pretty confident that I have solved the root cause of the killer octave problem. Other stated causes could be relegated to mitigating factors IMO. Out of 14 Chladni tests performed on different pianos so far, only the Diaphragmatic soundboards of Steinway had the sand go into the middle of the treble section of the bridge. All the other soundboards the sand stopped and never entered the treble section. This means the SS boards are too weak up in the treble section.
Check out my chladni tests on youtube and compare the MHAA to the SSO and see for your selves.
-chris

https://www.youtube.com/watch?v=aFbb1mzhx5E

Comment 1: I’ll follow with a question: comparing two unloaded but crowned soundboards, both Sitka and ribbed, one compression crowned the other radiused with ribs, which one has more stiffness??"

Reply to Comment 1: You can't tell, because stiffness varies significantly with rib aspect ratio, thickness, and spacing. One can always dial in various degrees of stiffness by changing various design elements.

I think Roy123 is spot on here. Plus Genes question isn't the right question, perhaps even a trick question. Acoustically, I think the real dilemma is weight. For the sake of argument, lets say both have identical stiffness values across the spectrum..Which could easily happen. Compression boards are lighter and offer more real estate in relation to that stiffness value.
But regarding which one has more stiffness? That doesn't matter. What matters is what you are shooting for in the design acoustically. .
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/11/19 06:09 AM
The question makes a point: stiffness does not manifest in any way until the soundboard assembly is loaded with string bearing. And challenges anyone to prove otherwise.
Maybe the trick that creeps into mind is the hesitation to quantify stiffness using that K algorithm, you did tie stiffness to pounding an unloaded board and observing sand patterns, no?
Since your boards operate on a loaded/mass principle. Have you tried hardwood rib stock like maple or ash? And if so, what were the tonal differences?
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/11/19 04:10 PM
One last try:
Focus.
Two boards of different design, both Sitka and unloaded.
Where is the stiffness?
Can your K algorithm define it or not?
I spent two years on my algorithms that give me a valuable tool . Since it is such an in-depth engineering subject and this is a piano forum, i would confer the same advice you give to others and suggest taking a class to study the subject in detail.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/12/19 12:50 AM
Fair enough - I understand - but I wasn’t asking you to give details about engineering and design algorithm tools, it was a yes or no question.
You did post a link about your algorithm as it applies to an unloaded board and my interpretation was that your not quantifying stiffness it appears to me to be more like wave impedance, sand pattern and resonate frequency.
But I’m ok to leave it at that. This isn’t going anywhere.
I will take that class if it comes my way.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/20/19 10:22 PM
With all the talk about soundboard stiffness, etc., I thought this simple little spreadsheet might be of interest to some of you.
RibStiffnessCalculator
Thats kinda cool. But not very useful. I would equate it to Chess. It's one thing to know how the pieces move, but another thing entirely knowing how they work together.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/21/19 04:10 PM
Well, I think everyone who knows anything about soundboards recognizes that the mass and stiffness of the board are two of the most important parameters that affect the sound of the piano. Clearly, selecting rib stiffness is an essential part of the design process. Of course, it is by no means the only one. The bridges also are a significant contributor to both soundboard mass and stiffness, and beyond that there are a large number of other factors that determine the tone and sustain of any particular piano. To suggest that it is not useful to know how rib width and height affect the rib's stiffness and mass is truly beyond my understanding--truly.

I design systems and subsystems for a living, and therefore know better than many who post in these pages that the performance of any system is due to the combination of many components that combine in ways both simple and complex to the behavior of the system as a whole. In any system, some components are crucial and play a large role in the performance of the system, and other components provide more subtle qualities. The ribs in a soundboard assembly are an example of a highly consequential part of the soundboard design. BTW, I find your analogy to chess, as stated, particularly inapt.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/21/19 07:08 PM
Originally Posted by Roy123
With all the talk about soundboard stiffness, etc., I thought this simple little spreadsheet might be of interest to some of you.
RibStiffnessCalculator


Trying to figure your math - for your "original rib cross section" - no stiffness ratio indicated - if I understand how you arrive at the same numbers for 'new rib and new rib any size' Id say the number should be 1.4046???
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/21/19 07:13 PM
Originally Posted by Gene Nelson
Originally Posted by Roy123
With all the talk about soundboard stiffness, etc., I thought this simple little spreadsheet might be of interest to some of you.
RibStiffnessCalculator


Trying to figure your math - for your "original rib cross section" - no stiffness ratio indicated - if I understand how you arrive at the same numbers for 'new rib and new rib any size' Id say the number should be 1.4046???



The stiffness ratios compare the 2 modified ribs to the original rib. To think of it another way, the stiffness of the original rib has been normalized to 1.
Roy123,
Thanks for your engaging discussion.
Your rib calculator is not useful because you will then be making changes without a purpose. I've studied hundreds of soundboards, mostly compression soundboards, and I have seen many makers try different things. Rather than isolate and analyze a single rib, it would be far better to the study rib structures of the assembly of different makers. Otherwise, a rib could be too small or too tall, or just have too much mass, or not enough mass. How would you know without the knowing the context of the entire structure? You can't go by one soundboard either, I've seen two Original Steinway M's with entirely different structures. Which one is correct? Or maybe neither? How would you know? Not by looking at a single rib. And regarding stiffness of a single rib, you can make a big change by just slightly sanding on the scalloped region. That should be in a stiffness equation since it has such a large effect. Another large effect on stiffness is the relationship of rib shape to scallop length and the bridge location on that rib. You take the same rib and change the other two factors and you have different stiffness. You take the same rib, same scalloping and just change the bridge location and you have different stiffness. No two pieces of wood a behave the same. You can have the same Height, Width and length and different stiffness. So i hope I have shown that there is much more involved..

When it comes to soundboard performance, your entire language is off. When an individual learns to belly from someone with a lifetime of experience, the discussion isn't mass, stiffness, or impedance. Its more procedural, craftsmanship skills, and experience that brings out the soundboards potential. I have made many improvements this year in my attempt at maximizing a soundboards potential- I find most soundboards are just too heavy. These days (using my software that has 4 years of development) I can successfully remove 5 lbs of weight and maintain structural integrity. I recently removed 8 lbs from a Mason and Hamlin. Many rebuilders I know and follow, just copy the original or, they make it worse by increasing the weight to size ratio, often just by reducing size. I never liked the idea of a 6 foot grand that acoustically performs like a 5 foot grand.

Also, I think there is more of an acoustical performance way of thinking, rather than an engineer structural way of thinking that makes a difference. I think this is the core of our disagreement.
Over the years, I have focused on things like how does the sound of a solid bridge differ from that of a laminated bridge? How about a maple cap vs.a Beech cap? What do the different woods sound like. I have heard the effects of Spruce versus Cedar panels. How about the sound of a Douglas Fir Panel? I can tell you it has an amazing dark timbre. Its just not in the awareness of the public. Another one is if the soundboard has a closed sound versus an open sound? What frequency should its fundamental tone be? How can it be manipulated to improve performance? What are the changes in performance of moving the acoustical centers? Here's a neat one, changing a rib with a thud sound (when bounced on the floor) to having a ringing tone.

Soundboards are suppose to enhance sound. They are not buildings, bridges, or floors with joists. Those have different goals.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/22/19 03:04 AM
Originally Posted by Chernobieff Piano
Roy123,
Thanks for your engaging discussion.
Your rib calculator is not useful because you will then be making changes without a purpose. I've studied hundreds of soundboards, mostly compression soundboards, and I have seen many makers try different things. Rather than isolate and analyze a single rib, it would be far better to the study rib structures of the assembly of different makers. Otherwise, a rib could be too small or too tall, or just have too much mass, or not enough mass. How would you know without the knowing the context of the entire structure? You can't go by one soundboard either, I've seen two Original Steinway M's with entirely different structures. Which one is correct? Or maybe neither? How would you know? Not by looking at a single rib. And regarding stiffness of a single rib, you can make a big change by just slightly sanding on the scalloped region. That should be in a stiffness equation since it has such a large effect. Another large effect on stiffness is the relationship of rib shape to scallop length and the bridge location on that rib. You take the same rib and change the other two factors and you have different stiffness. You take the same rib, same scalloping and just change the bridge location and you have different stiffness. No two pieces of wood a behave the same. You can have the same Height, Width and length and different stiffness. So i hope I have shown that there is much more involved..

When it comes to soundboard performance, your entire language is off. When an individual learns to belly from someone with a lifetime of experience, the discussion isn't mass, stiffness, or impedance. Its more procedural, craftsmanship skills, and experience that brings out the soundboards potential. I have made many improvements this year in my attempt at maximizing a soundboards potential- I find most soundboards are just too heavy. These days (using my software that has 4 years of development) I can successfully remove 5 lbs of weight and maintain structural integrity. I recently removed 8 lbs from a Mason and Hamlin. Many rebuilders I know and follow, just copy the original or, they make it worse by increasing the weight to size ratio, often just by reducing size. I never liked the idea of a 6 foot grand that acoustically performs like a 5 foot grand.

Also, I think there is more of an acoustical performance way of thinking, rather than an engineer structural way of thinking that makes a difference. I think this is the core of our disagreement.
Over the years, I have focused on things like how does the sound of a solid bridge differ from that of a laminated bridge? How about a maple cap vs.a Beech cap? What do the different woods sound like. I have heard the effects of Spruce versus Cedar panels. How about the sound of a Douglas Fir Panel? I can tell you it has an amazing dark timbre. Its just not in the awareness of the public. Another one is if the soundboard has a closed sound versus an open sound? What frequency should its fundamental tone be? How can it be manipulated to improve performance? What are the changes in performance of moving the acoustical centers? Here's a neat one, changing a rib with a thud sound (when bounced on the floor) to having a ringing tone.

Soundboards are suppose to enhance sound. They are not buildings, bridges, or floors with joists. Those have different goals.
-chris









All uninspired self gratifying bologna.
Soundboard assemblies that differ from yours are not buildings, bridges or floor joists, get over it.
Have you ignored the fact that most everyone that does this work is wrong with the exception of you?
Books included. I should be humbled.
And boards do not enhance sound. they try to bring out The full potential of the input energy and most usually fall short to some degree or another - that is except yours, right? Superior, right?
I just cannot take you seriously.
Thanks for your thoughts Gene,
But your thinking is a bit fuzzy.
Since this is a piano forum, i'll ignore the personal attacks and address your piano related query.

You said:
"And boards do not enhance sound."

Then in the same sentence you said:

" they try to bring out The full potential of the input energy and most usually fall short to some degree or another"

That's practically the definition of enhancement Gene.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/22/19 08:24 PM
Enhance in Webster’s is to heighten and or increase, to augment.
Essentially to make more of what’s there by adding something.
The energy coming out of the board cannot be more than the input.

Finger moves key that moves hammer that moves string then bridge, board and air.
Energy losses for every interaction.

It’s a fallacy to divorce yourself from the way I react to you.
Gene,

Of course the input of energy is transduced . But, its going from being an inaudible energy to an audible energy. Hence, its volume is enhanced. Amplification would be adding energy. Which is not the case.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/22/19 11:34 PM
I specifically said sound, not volume.
But you can be right Chris, its ok.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/23/19 12:41 AM
Originally Posted by Chernobieff Piano
Roy123,
Thanks for your engaging discussion.
(1)Your rib calculator is not useful because you will then be making changes without a purpose. I've studied hundreds of soundboards, mostly compression soundboards, and I have seen many makers try different things. (2) Rather than isolate and analyze a single rib, it would be far better to the study rib structures of the assembly of different makers. Otherwise, a rib could be too small or too tall, or just have too much mass, or not enough mass. How would you know without the knowing the context of the entire structure? You can't go by one soundboard either, I've seen two Original Steinway M's with entirely different structures. Which one is correct? Or maybe neither? How would you know? Not by looking at a single rib. And regarding stiffness of a single rib, you can make a big change by just slightly sanding on the scalloped region. That should be in a stiffness equation since it has such a large effect. Another large effect on stiffness is the relationship of rib shape to scallop length and the bridge location on that rib. You take the same rib and change the other two factors and you have different stiffness. You take the same rib, same scalloping and just change the bridge location and you have different stiffness. No two pieces of wood a behave the same. You can have the same Height, Width and length and different stiffness. (3)So i hope I have shown that there is much more involved..

When it comes to soundboard performance, your entire language is off. When an individual learns to belly from someone with a lifetime of experience,(4) the discussion isn't mass, stiffness, or impedance. Its more procedural, craftsmanship skills, and experience that brings out the soundboards potential. I have made many improvements this year in my attempt at maximizing a soundboards potential-(5) I find most soundboards are just too heavy. These days (using my software that has 4 years of development) I can successfully remove 5 lbs of weight and maintain structural integrity. I recently removed 8 lbs from a Mason and Hamlin. Many rebuilders I know and follow, just copy the original or, they make it worse by increasing the weight to size ratio, often just by reducing size. I never liked the idea of a 6 foot grand that acoustically performs like a 5 foot grand.

(6)Also, I think there is more of an acoustical performance way of thinking, rather than an engineer structural way of thinking that makes a difference. I think this is the core of our disagreement.
Over the years, I have focused on things like how does the sound of a solid bridge differ from that of a laminated bridge? How about a maple cap vs.a Beech cap? What do the different woods sound like. I have heard the effects of Spruce versus Cedar panels. How about the sound of a Douglas Fir Panel? I can tell you it has an amazing dark timbre. Its just not in the awareness of the public. Another one is if the soundboard has a closed sound versus an open sound? What frequency should its fundamental tone be? How can it be manipulated to improve performance? What are the changes in performance of moving the acoustical centers? Here's a neat one, changing a rib with a thud sound (when bounced on the floor) to having a ringing tone.

(7)Soundboards are suppose to enhance sound. They are not buildings, bridges, or floors with joists. Those have different goals.
-chris


I have bolded and numbered a few things so I can respond to them
(1) Oh, so changing the stiffness of a rib is a change without a purpose? Need I say more?
(2) Yes, the entire rib structure is what counts, but the entire rib structure comprises a number of constituent parts--most importantly, individual ribs. You can't change or analyze the whole structure without considering its components.
(3) Yes, there is tons more involved, which I explicitly stated. I never claimed otherwise nor would anyone with any domain knowledge.
(4) If so, then I think there's lots of opportunities that are being missed. Thinking about procedures, skill sets, and experience sounds like a good way to make a soundboard that hasn't had the benefit of new and creative thinking.
(5) Indeed? Then you should be extraordinarily interested in how the cross-sectional aspect ratio of a rib can greatly decrease weight while maintaining or increasing stiffness.
(6) IMO, this statement is just goobledygook. The acoustical performance arises from the totality of the structural design. To think they are separate from each other simply ignores the reality that a soundboard is a structural, mechanical assembly, which is both subtle and therefore complex in its design. There are no fairies in there, and no magic--it's all science.
(7) Who said they were buildings or floors? Not I nor anyone else with any sense or understanding. However, to pretend that the totality of the soundboard in its structure, design, and execution is not what produces the lovely sound we're all after is REALLY missing the point.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/23/19 01:03 AM
Originally Posted by Gene Nelson
I specifically said sound, not volume.
But you can be right Chris, its ok.

Originally Posted by Gene Nelson
I specifically said sound, not volume.
But you can be right Chris, its ok.


But for the sake of discussion let’s include power as opposed to volume.
Hammer hits string and all of the tone, partials, harmonics and even power is in the string.
Then all of this stuff gets into the soundboard that only moves air.
Certainly the sound and power from the strings is altered so it’s more audible but the board does not add anything, it tries to get 100% of the string energy out as moving air that gets into our ears.
My point is that no soundboard does this perfectly, 100% efficiently. That includes power. We hear a volume change but the power is less as it moves across the system.
Roy123,
Thank you for the response.
My answers in bold.
(1) Oh, so changing the stiffness of a rib is a change without a purpose? Need I say more?
(2) Yes, the entire rib structure is what counts, but the entire rib structure comprises a number of constituent parts--most importantly, individual ribs. You can't change or analyze the whole structure without considering its components.
(3) Yes, there is tons more involved, which I explicitly stated. I never claimed otherwise nor would anyone with any domain knowledge.

You answered your own questions here. 3 answers 2, 2 answers 1

(4) If so, then I think there's lots of opportunities that are being missed. Thinking about procedures, skill sets, and experience sounds like a good way to make a soundboard that hasn't had the benefit of new and creative thinking.

Talk about goobledygook?

(5) Indeed? Then you should be extraordinarily interested in how the cross-sectional aspect ratio of a rib can greatly decrease weight while maintaining or increasing stiffness.
Cross sectional area all by itself is useless. You seem to think that the bridge is always in the center of a rib, and you don’t take the scalloping into consideration. Because of the offset of the bridge and the asymmetrical load being placed on the rib, means acoustically, the rib should not be the same cross section across its length. Thus making it low in value as an analysis factor.

(6) IMO, this statement is just goobledygook. The acoustical performance arises from the totality of the structural design. To think they are separate from each other simply ignores the reality that a soundboard is a structural, mechanical assembly, which is both subtle and therefore complex in its design. There are no fairies in there, and no magic--it's all science.
Do you think everything you don’t at first understand to be goobledygook? You can’t seem to bridge the gap between mechanical function to acoustical performance. Here’s a video in which you can watch a master violin maker enhance the sound of the violin for the artist in front of a crowd. And you won’t hear the words mass, stiffness or impedance. And he was a physicist!!! https://www.youtube.com/watch?v=c8-rOvWeV8k&t=16s

(7) Who said they were buildings or floors? Not I nor anyone else with any sense or understanding. However, to pretend that the totality of the soundboard in its structure, design, and execution is not what produces the lovely sound we're all after is REALLY missing the point.

My point is that using the same math that is used to engineer floors and buildings , fails to produce a highly efficient wooden sounding board. That requires an ear.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/23/19 03:35 AM
My point is that using the same math that is used to engineer floors and buildings , fails to produce a highly efficient wooden sounding board. That requires an ear.

That’s more like an uninformed and totally biased opinion.
I think your point is consistent with things I tell you about that you misinterpret as attack.
Being superior and making people out to be wrong who don’t do compression crowning the way you do.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 12/23/19 01:27 PM
Originally Posted by Chernobieff Piano
Roy123,
Thank you for the response.
My answers in bold.
(1) Oh, so changing the stiffness of a rib is a change without a purpose? Need I say more?
(2) Yes, the entire rib structure is what counts, but the entire rib structure comprises a number of constituent parts--most importantly, individual ribs. You can't change or analyze the whole structure without considering its components.
(3) Yes, there is tons more involved, which I explicitly stated. I never claimed otherwise nor would anyone with any domain knowledge.

You answered your own questions here. 3 answers 2, 2 answers 1

(4) If so, then I think there's lots of opportunities that are being missed. Thinking about procedures, skill sets, and experience sounds like a good way to make a soundboard that hasn't had the benefit of new and creative thinking.

Talk about goobledygook?

(5) Indeed? Then you should be extraordinarily interested in how the cross-sectional aspect ratio of a rib can greatly decrease weight while maintaining or increasing stiffness.
Cross sectional area all by itself is useless. You seem to think that the bridge is always in the center of a rib, and you don’t take the scalloping into consideration. Because of the offset of the bridge and the asymmetrical load being placed on the rib, means acoustically, the rib should not be the same cross section across its length. Thus making it low in value as an analysis factor.

(6) IMO, this statement is just goobledygook. The acoustical performance arises from the totality of the structural design. To think they are separate from each other simply ignores the reality that a soundboard is a structural, mechanical assembly, which is both subtle and therefore complex in its design. There are no fairies in there, and no magic--it's all science.
Do you think everything you don’t at first understand to be goobledygook? You can’t seem to bridge the gap between mechanical function to acoustical performance. Here’s a video in which you can watch a master violin maker enhance the sound of the violin for the artist in front of a crowd. And you won’t hear the words mass, stiffness or impedance. And he was a physicist!!! https://www.youtube.com/watch?v=c8-rOvWeV8k&t=16s


(7) Who said they were buildings or floors? Not I nor anyone else with any sense or understanding. However, to pretend that the totality of the soundboard in its structure, design, and execution is not what produces the lovely sound we're all after is REALLY missing the point.

My point is that using the same math that is used to engineer floors and buildings , fails to produce a highly efficient wooden sounding board. That requires an ear.
The ear is the test of the mechanical structure that defines the board To use an analogy, let's say you want to design a car that can go from 0-60 very quickly. Measuring its acceleration is the means to judge the success of its design. It's the same with soundboards. Listening to the piano is the measure of success. The success of failure of the listening test is result of the entirety of the soundboard's design and execution.

-chris


As I said, there are many considerations in designing a soundboard. You mentioned the value of compression-crowned boards as being more stiff. Higher aspect-ratio ribs are another way to increase the stiffness of soundboards without adding mass. Understanding the incredible sensitivity of the rib's stiffness to its height might provide a better understanding of the effects of scalloping, which could be useful.
There is no gap between the mechanical design and the acoustical performance. To think otherwise is a profound misunderstanding on your part. A soundboard is its structure, its structure is the soundboard. It's structure is utterly and 100% responsible for its acoustical performance. Where else would its acoustic capabilities come from? Some magical realm? I agree that it may be extremely difficult to map the mechanical structure to the acoustic performance, but many technologies are complex and difficult to analyze.
Also, yes, the same math that applies to floor design applies to soundboard design. It is the mathematics of the analysis of mechanical structures. In addition to that math, the soundboard designer should also understand the math that describes the transduction of mechanical vibrations into the production of sound. Engineers who design speakers usually understand that math quite well. The difference is the end goal. Floors are designed to safely support some defined load, and soundboards are designed to efficiently transduce the mechanical vibration of the strings into pleasing sound.
Everything I'm trying to say can be summed up simply. The soundboard is a mechanical structure. All aspects of its design, including its constituent parts, determine how well it will function as a transducer to produce a desired result.

I will give you the last word. I don't know how to express my thoughts any more clearly than I already have, though others may be able to do a better job than I.
Roy123,
You said:
There is no gap between the mechanical design and the acoustical performance. To think otherwise is a profound misunderstanding on your part. A soundboard is its structure, its structure is the soundboard. It's structure is utterly and 100% responsible for its acoustical performance. Where else would its acoustic capabilities come from? Some magical realm?

Everything you write makes sense on the surface, but the misunderstanding is not on my part, but rests on your shoulders. That's why you keep referring to "that it must be magic". No math, or analysis of the structure, can explain why one board sounds awful, and another identical board sounds great. In the video i presented, Fry didn't make any structural changes to improve the tone. Its not magic Roy123, but a deeper understanding. You may be well regarded in your field of expertise (engineering?) but that doesn't necessarily lend itself to another branch of expertise. Musical instrument Acoustics is most likely a sub- branch of Acoustics and that is a lifelong study in itself. Most of the changes that are made to improve the acoustical performance of a sounding board are subtle and often can't be detected by the eye. Again referring to the video, Fry mentions a drop of lacquer in a critical area can be tool. Just a scrape or two made a huge difference.
The piano soundboard may not be as subtle as that due to its size, but the ideas are the same. Steinways Diaphragmatic soundboard is an example.
The engineering is good up to a point. And I understand that belief, because the industry as a whole has a mass production mindset. Often the acoustic manipulations are not done on a piano soundboard. But what a difference they make.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/23/19 08:59 PM
So if i understand this correctly: Chris’ Unique in depth knowledge of the acoustics of a piano soundboard that exceeds that of an engineer’s or other rebuilders amounts to dripping lacquer on the board, trimming it with some tool, pounding it and watching for ideal sand patterns, all while unloaded?
I’ll stick with engineering.
I made my first soundboard in 1978. I am proud of the soundboards I produce and the advancements that I have made. I will defend them when challenged, and amaze anyone who hears them.

Unlike Gene, who cannot defend his product and must resort to name calling and snarky comments, when he feels threatened by others accomplishments.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/23/19 11:49 PM
Chris, I have never challenged your soundboards. If you recall I complemented you on your production of 50 boards per year, told you that you must do good work if you do that many, also stated my respect for anyone in this business who tries to make a better piano.
Besides, I could not criticize your product because I have not encountered it/them, that would be unethical - I’m certain you can understand that, no??
I do have much experience with the problems with compression crowned boards and if you re-read my posts, my criticisms are based on that process.
What I have challenged is your claim to superiority and you just don’t get the message.
I have defended my product just fine, only to be told by you that everything I do is wrong or it cannot be done or I’m building floors and bridges as opposed to soundboards. no reasonable dialogue could be expected as a result.
Like I told you Chris, you cannot divorce yourself from how I react to you.
You need to reflect on yourself just a bit. Possibly just a little humility??
Gene,
When I mentioned Compression soundboards are superior to RC&S boards that was 500 posts ago. You've been a BULLY and STALKER ever since.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/24/19 01:20 AM

Originally Posted by Chernobieff Piano
Gene,
When I mentioned Compression soundboards are superior to jRC&S boards that was 500 posts ago. You've been a BULLY and STALKER ever since.


The mention was not generalized.
And now the victim angle.
I’m outa here.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 12/25/19 12:06 AM
FWIW

I am not an expert on soundboards and never expect to build one or even install one. Just has a question about what you fine folks considered an "oilcanned" soundboard to be because I doubted a soundboard could actually act like the bottom of an oil can.

Anyhoo, the discussion stayed with soundboards with some posters having very different views on the subject. Not knowing all that much myself, I found myself relying on some adages to try to sort out the wheat from the chaff:

If someone is focusing on themselves rather than the subject, they are probable full of it, or at least full of themselves, if there is a difference.

If someone is using typical words in untypical manners, they don't know the words to use, and nobody else can really know what they mean either.

A sure way to spot an abuser is to call them on it. If they become defensive, or offensive, there can be little doubt.

When there are aspects to a subject that can only be experienced, and not analysed, those aspects belong in la-la land.

Someone that fully understands a subject can explain it in clear terms.

A professional, humble person always points out their limits.

If you argue with a fool, people will assume you are a fool, too.


MERRY CHRISTMAS!!!
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/25/19 01:38 AM
Merry Christmas
I’ll try to restate my opinion about this based on personal experience.
I have a soundboard in the shop (Out of the old piano being restored)that has as much or more negative crown as it may have positive crown when new prior to glue up in the piano belly. let’s call this an oil canned board for the sake of my explanation.
The only way I can explain that makes sense to me in relation to oil canning is:
It’s a compression board. The process of crowning involves drying the board and then gluing it to flat sawn ribs when removed from the dry box.
As the board takes up moisture it wants to expand and cannot because it is restrained by the ribs so it crowns and bows up instead.
If the moisture change from dry to ambient is extreme the cellular structure of the board can be damaged beyond repair. The fiber strength proportional limit exceeded. this can happen when new before glue up. Or later in its life after string bearing is applied as the process pushes the board very close to its FSPL.
Side note: to demo FSPL limit just start tapping on a piece of Sitka spruce with a hammer. When the dent you make will not return to undented, the FSPL has been exceeded beyond repair.
So my theory is that the board in my shop is a victim of this abuse (not pounding on it with a hammer). The cell structure is damaged beyond repair. However, the flat sawn ribs are still in tact. Initially they resist whatever crown there may have been and now they dominate the shape of the damaged board.
They bend or pull the board in the opposite direction and the board cannot resist, it’s a limp weeny. the ribs pull in the opposite direction because of cell structure and other reasons that apply to wood that warps with moisture changes.
But it’s only all a theory. I cannot prove it.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 12/25/19 02:11 AM
Originally Posted by Gene Nelson
Merry Christmas
I’ll try to restate my opinion about this based on personal experience.
I have a soundboard in the shop (Out of the old piano being restored)that has as much or more negative crown as it may have positive crown when new prior to glue up in the piano belly. let’s call this an oil canned board for the sake of my explanation.
The only way I can explain that makes sense to me in relation to oil canning is:
It’s a compression board. The process of crowning involves drying the board and then gluing it to flat sawn ribs when removed from the dry box.
As the board takes up moisture it wants to expand and cannot because it is restrained by the ribs so it crowns and bows up instead.
If the moisture change from dry to ambient is extreme the cellular structure of the board can be damaged beyond repair. The fiber strength proportional limit exceeded. this can happen when new before glue up. Or later in its life after string bearing is applied as the process pushes the board very close to its FSPL.
Side note: to demo FSPL limit just start tapping on a piece of Sitka spruce with a hammer. When the dent you make will not return to undented, the FSPL has been exceeded beyond repair.
So my theory is that the board in my shop is a victim of this abuse (not pounding on it with a hammer). The cell structure is damaged beyond repair. However, the flat sawn ribs are still in tact. Initially they resist whatever crown there may have been and now they dominate the shape of the damaged board.
They bend or pull the board in the opposite direction and the board cannot resist, it’s a limp weeny. the ribs pull in the opposite direction because of cell structure and other reasons that apply to wood that warps with moisture changes.
But it’s only all a theory. I cannot prove it.


Thanks Gene!

OK, what you just described is an unloaded board with reverse crown and call it "oilcanned". In my mind, it is collapsed. (The bottom of an oil can pops back.) Others have described a board with inverted crown resulting in negative downbearing in part of the scale when loaded, but with regular crown when unloaded as "oilcanned". I my mind it had inappropriate downbearing and/or poor construction. (The crown came back, but did it"pop" like an oilcan?) OK, so there is no agreed upon definition of what an "oilcanned" board is - let alone what might cause the various faults that coincide with the various conditions.

But just to muse, and perhaps give you another possibility as to what happened to the board you mentioned, take a board, any board. Loaded it with ridiculous downbearing. Give it humidity cycles for, say, 100 years. I expect it would level out with nearly zero downbearing, but with negative crown. Might have sounded OK, too.

Btw, I googled "fiber strength proportional limit" and only got a few hits, all on Piano World...
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/25/19 02:30 AM
Maybe try fiber stress proportional limit.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 12/25/19 02:32 AM
I think if I were the put my example board back in the piano and string it up the board would comply with the plane of the strings. That’s kind of popping back wouldn’t you say?
If the physical weight of a board is important:

Here are some stats from 3 Steinway M's. 1) An rc&s from a well known rebuilder, 2) An Original Steinway Diaphragmatic, And one of my boards

1) 16.8 lbs., longest rib 36", Fundamental vibration frequency 79hz, stiffness factor 520
2) 15.1 lbs, longest rib 42" , Fundamental vibration frequency 51 hz, stiffness factor 282
3) 13.5 lbs, longest rib 42", Fundamental Vibration frequency 56hz, stiffness factor 300

I'm able to reduce the weight by targeting the mass where its needed, and eliminating the mass that's not needed. Usually a 1/2 -1lb from the rib stock, and 1 pound off a diaphragmatic panel, more from other panels.

I'm currently working on a 4'9" Behning Grand, as working on small grands offers unique challenges. This tiny board weighs a whopping 15 lbs. It had a very thick panel 11mm in the top treble, down to 9mm in the bass.

Overall Steinway boards are the lightest and may be a distinguishing factor of theirs.
-chris
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/30/19 02:32 PM
Holy cow!, with all this,--- this little Behning would be a good example, if you show the factory ribbing, why it is incorrect, and what you are going to do and why., I am very curious as to where exactly you determine the active nodal zones. "sweet spots".
Seems like some, or should I say most are confused with loud speaker applications, like a stereo.
I don't remember any discussions re; nodal placement. Major belly changes are made, and there is no input as to why the factory was so wrong. The smaller the soundboard, of course is for more difficulty, for sure. Let's see.
Richard Blais
Craig,
Contact me via PM and we'll continue this conversation privately and bypass the naysayers.
-chris
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/31/19 03:53 PM
Craig remembers the very first thing you said to us, was,
"what we do could not be done", We were bothered by naysayers once, but not any more, we are too busy doing the impossible.
So---why do this in private, when there is something to learn, naysayers won't learn otherwise.
Hat's off to you for your efforts. But in the past you ignored ours, no questions.
Let's keep this in the public eyes, I would be way OK with that.
Now how do we proceed, I have a suggestion.
!5,ooo comments, and this oilcan thing is still ridiculously a mystery.

If a piano never had been strung up when new, placed in a home here in New England the sound board would be just as shrunken ,and reversed crown, "without ever having strings" "give that some thought".

Just to mention, we did an 1872 Bluthner SB re-crown, and it had what must be machine crowned ribbing. "I was surprised"
They were in need of steam shaping, and they went right back in. "the piano"
Maybe we can add something positive to this, sound board construction is not only how stiff everything is.
It's like a fox hunt, it's the pursuit of the pray that is important, no more foxes, no more pursuit, "excitement" so there seem to be many that don't want reality. "end of the chase"
Richard Blais.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 12/31/19 06:59 PM
Inquiring minds want to know...😁

Pwg
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 12/31/19 10:29 PM
.Steinway pulsators are pretty interesting., M&H had them also. they control the sweet spot. "undulation"
This behavior can be demonstrated With a table, a strip of wood a tuning fork, and a small clamp.
Oh, yes we know something about naysayers, because we have met some.

http://forum.pianoworld.com/ubbthreads.php/topics/1681779/original%20soundboard%20recrowning.html
R. Blais.
Craig and Richard,
Actually, I find your work fascinating, it's just not for me. I follow you guys because I am always open to learning new things. As regards to what you guys do, i'm on the fence about it to be honest. On the one hand you offer "all original" to your clients which is very valuable to some folks, but on the other hand its a fiber fatigued material that has existed under unknown conditions for 100 years. Another problem for me, is that the Original soundboard has flaws that I do not want to copy or re-use. These flaws are caused by mass production and include:

1) Original poor design. I've read many accounts of when a piano designer made a new design, it would run through the process and the design would later be tweaked and improved. That's natural. But if the designer was fired or died or whatever, the flawed design continued on. Often for decades.

2) Heavy Weight. I realized that just about every single old soundboard is overbuilt. Way overbuilt. With heavy rib scales, heavy panels, and heavy bridges. Often they are several pounds too heavy.

3) Rib scales. Again, after studying many boards, i have found only 2 that had any semblance of thought in them. The choices of lengths relative to their Height and Width was random. An engineered rib scale introduces evenness and balance which is crucial for stiffness control across the board.

4) Rib Design. The rib itself is often done without thought. The scalloping serves the purpose of aligning the "driving point" underneath the bridge. When the driving point is off then the soundboard behaves like an engine with the wrong firing order.

5) Panel grading and thinning. This too is crucial for performance and weight control. There are multiple grading plans that can be effectively applied depending on style. Wolfenden's favorite was the "wedge".

Keep doing what you enjoy doing.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/01/20 05:09 PM
Originally Posted by Chernobieff Piano
Craig and Richard,
Actually, I find your work fascinating, it's just not for me. I follow you guys because I am always open to learning new things. As regards to what you guys do, i'm on the fence about it to be honest. On the one hand you offer "all original" to your clients which is very valuable to some folks, but on the other hand its a fiber fatigued material that has existed under unknown conditions for 100 years. Another problem for me, is that the Original soundboard has flaws that I do not want to copy or re-use. These flaws are caused by mass production and include:

Curious what new things you learned from Craig and Richard?
For anyone installing a new board every week, to me that is mass production.

1) Original poor design. I've read many accounts of when a piano designer made a new design, it would run through the process and the design would later be tweaked and improved. That's natural. But if the designer was fired or died or whatever, the flawed design continued on. Often for decades.

The implication being that at least one soundboard designer who mass produces has a flawless design to compare all others against??

2) Heavy Weight. I realized that just about every single old soundboard is overbuilt. Way overbuilt. With heavy rib scales, heavy panels, and heavy bridges. Often they are several pounds too heavy.

Too much weight and overbuilt as compared with your design criteria. You never mention scale design and tension, string bearing load - all play a roll in board response vs overall mass. Again, overbuilt as compared with your design criteria.

3) Rib scales. Again, after studying many boards, i have found only 2 that had any semblance of thought in them. The choices of lengths relative to their Height and Width was random. An engineered rib scale introduces evenness and balance which is crucial for stiffness control across the board.

The ribs on most compression boards simply hold the board together, not much engineering required. I’ll agree about controlling stiffness.

4) Rib Design. The rib itself is often done without thought. The scalloping serves the purpose of aligning the "driving point" underneath the bridge. When the driving point is off then the soundboard behaves like an engine with the wrong firing order.

Ribs are not driving members of the assembly, they are driven. A deliberate radius is very efficient at getting needed support under the bridge. And why would anyone want to do that? How about supporting the string bearing load as well as adding responsiveness to string energy? Flat sawn ribs tend to do the opposite.

5) Panel grading and thinning. This too is crucial for performance and weight control. There are multiple grading plans that can be effectively applied depending on style. Wolfenden's favorite was the "wedge".

You stated earlier that Wolfendens book was useless???
Again, soundboard mass and string scale and bearing load must be included in the decision on mass.


Keep doing what you enjoy doing.
-chris

Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/01/20 06:44 PM
Im thinking the OP is correct. I cannot come up with a scenario that can describe an oilcanned piano soundboard.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/01/20 07:31 PM
I am however interested in flat sawn rib designs coupled with a compression designed board and could stand to be enlightened:
Lets take an imaginary rib that is 30 inches long. I induce crown by the compression technique and end up with a 60 foot radius by intentional design.
So for reasons of experiment and desire to understand, I take a 30 piece of wood on my work bench and induce a 60 foot radius into it.
How do I do this?
Simple, calculate the sag or sagitta of the arc "s" where s = r - (the square root of r squared - l squared).
Where s is the sag or sagitta or the amount of crown induced (0.156"), r is the radius (60 feet) l is half the length of the rib or (15 inches).
When you do this calc, be certain to not mix inches and feet - stick with one or the other.
So using this calculation I end up with a sag, or sagitta or available crown of about 0.156 inches. A reasonable amount of crown to work with in my opinion.
So I go to my drill index and get a jobber bit that is 0.157 (couldnt find 0.156) and put it under the rib directly in the middle .then hold the ends down against the work bench
So now for the assembly part :
The typical compression board has flat sawn ribs that simply hold the board together and at the end of the glue up/compression process lets say that this imaginary 30 inch rib ends up with a 60 foot radius and about 0.156 inch of available crown - prior to loading with string bearing. My question is how does this rib move under string bearing load if the rib is not designed to support the string bearing load?? Its the board that supports the load in this scenario and the flat sawn rib works against the crown as it wants to go flat.
Just bend a piece of wood and then let it go - it wants to return to its original shape.
Now some compression board designers will buttress the ends of this rib very snugly into the rim of the piano with the intent that the piano rim will not allow it to expand and therefore give support to the string bearing.
Great idea. I believe it has been proven that end grain oriented support like a 4x4 beam that supports a deck or bridge can be stronger than steel.
However, the assumption that the piano rim is absolutely solid and will not move and therefore will not allow this rib to expand under load and therefore retain its sagitta or crown is a little difficult to believe because all of the wood on the entire piano moves and this imaginary rib will move with the rim.
Just how much will the length of this 30 inch rib that has 60 foot radius, with 0.156 inch crown or sagitta under string load change?
My bench test shows that the length of this rib when flat as opposed to when 0.156 inch of crown or sagitta is induced using my jobber bit will change its length by an almost not measurable amount. Possibly only a couple thousandths of an inch or less. I dont have the measuring device that can accurately measure and maybe someone knows the math that can define this change in length. Possibly a variation of the sagitta calc? Im not too good at math.
The piano rim moves that much or more, I dont care how solid it is, what wood its made of or if there are Mason Hamlin restraints assisting it. This flat sawn rib may or may not retain any string bearing support or crown or sagitta assumed by buttressing the end grain into the inner rim.
Now maybe string bearing support and crown retention are not a priority in this sort of design?


What am I missing?
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 01/01/20 08:17 PM
A compression crowned board structure is a pre-stressed structure. The panel is restrained by the ribs from expanding across the grain as long as the RH does not reach the RH the panel possessed at the time of rib gluing.

The ribs do not directly support the downbearing. The glue line of the ribs and bridge, (if crown conformed along the gluing line), hold the entire tensed panel and rib structure together. So one must engineer it as one engineers a tensed, arched structure to resist loads.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/01/20 08:59 PM
Originally Posted by Ed McMorrow, RPT
A compression crowned board structure is a pre-stressed structure. The panel is restrained by the ribs from expanding across the grain as long as the RH does not reach the RH the panel possessed at the time of rib gluing.

The ribs do not directly support the downbearing. The glue line of the ribs and bridge, (if crown conformed along the gluing line), hold the entire tensed panel and rib structure together. So one must engineer it as one engineers a tensed, arched structure to resist loads.


Thank you Ed
Is there a technique where crown can be persuaded to conform to the glue line?
Seems to me that would require the use of some sort of device to help shape the board as it is taking up moisture??
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 01/02/20 02:12 AM
Your welcome Gene. I enjoy your posts too.

I have a bridge gluing caul that has a shape that mimics what I usually find in Steinway pianos. It assumes the old bridge has lost some crown conformation over time.

I also try to conform my cap stock to the crown of the bridge root. I don't like to force the cap stock down to the glue line that leaves forces twisting the bridge away from crown.
Originally Posted by Gene Nelson
I am however interested in flat sawn rib designs coupled with a compression designed board and could stand to be enlightened:
Lets take an imaginary rib that is 30 inches long. I induce crown by the compression technique and end up with a 60 foot radius by intentional design.
So for reasons of experiment and desire to understand, I take a 30 piece of wood on my work bench and induce a 60 foot radius into it.
How do I do this?
Simple, calculate the sag or sagitta of the arc "s" where s = r - (the square root of r squared - l squared).
Where s is the sag or sagitta or the amount of crown induced (0.156"), r is the radius (60 feet) l is half the length of the rib or (15 inches).
When you do this calc, be certain to not mix inches and feet - stick with one or the other.
So using this calculation I end up with a sag, or sagitta or available crown of about 0.156 inches. A reasonable amount of crown to work with in my opinion.
So I go to my drill index and get a jobber bit that is 0.157 (couldnt find 0.156) and put it under the rib directly in the middle .then hold the ends down against the work bench
So now for the assembly part :
The typical compression board has flat sawn ribs that simply hold the board together and at the end of the glue up/compression process lets say that this imaginary 30 inch rib ends up with a 60 foot radius and about 0.156 inch of available crown - prior to loading with string bearing. My question is how does this rib move under string bearing load if the rib is not designed to support the string bearing load?? Its the board that supports the load in this scenario and the flat sawn rib works against the crown as it wants to go flat.
Just bend a piece of wood and then let it go - it wants to return to its original shape.
Now some compression board designers will buttress the ends of this rib very snugly into the rim of the piano with the intent that the piano rim will not allow it to expand and therefore give support to the string bearing.
Great idea. I believe it has been proven that end grain oriented support like a 4x4 beam that supports a deck or bridge can be stronger than steel.
However, the assumption that the piano rim is absolutely solid and will not move and therefore will not allow this rib to expand under load and therefore retain its sagitta or crown is a little difficult to believe because all of the wood on the entire piano moves and this imaginary rib will move with the rim.
Just how much will the length of this 30 inch rib that has 60 foot radius, with 0.156 inch crown or sagitta under string load change?
My bench test shows that the length of this rib when flat as opposed to when 0.156 inch of crown or sagitta is induced using my jobber bit will change its length by an almost not measurable amount. Possibly only a couple thousandths of an inch or less. I dont have the measuring device that can accurately measure and maybe someone knows the math that can define this change in length. Possibly a variation of the sagitta calc? Im not too good at math.
The piano rim moves that much or more, I dont care how solid it is, what wood its made of or if there are Mason Hamlin restraints assisting it. This flat sawn rib may or may not retain any string bearing support or crown or sagitta assumed by buttressing the end grain into the inner rim.
Now maybe string bearing support and crown retention are not a priority in this sort of design?


What am I missing?


A lot.
How does one go from professed expert to suddenly a curious student?

I'll try an help you tho. The rib IS designed to hold the load. When Ed says it doesn't directly support the load, this is a misleading statement on his part. Because indirect support by de facto becomes direct support. It's a laminated structure that undergoes a hygroscopic process. Your bench test is a false read because it doesn't take into account woods behavior. A straight rib is not the same as a straight rib with a natural bow for instance. The assumption seems to be that flat ribs are glued on, then the board is glued in flat and expected to crown. In that scenario, you would be correct. But that would be bad bellywork.
\Hope that helps.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/02/20 04:43 AM
Originally Posted by Chernobieff Piano
Originally Posted by Gene Nelson
I am however interested in flat sawn rib designs coupled with a compression designed board and could stand to be enlightened:
Lets take an imaginary rib that is 30 inches long. I induce crown by the compression technique and end up with a 60 foot radius by intentional design.
So for reasons of experiment and desire to understand, I take a 30 piece of wood on my work bench and induce a 60 foot radius into it.
How do I do this?
Simple, calculate the sag or sagitta of the arc "s" where s = r - (the square root of r squared - l squared).
Where s is the sag or sagitta or the amount of crown induced (0.156"), r is the radius (60 feet) l is half the length of the rib or (15 inches).
When you do this calc, be certain to not mix inches and feet - stick with one or the other.
So using this calculation I end up with a sag, or sagitta or available crown of about 0.156 inches. A reasonable amount of crown to work with in my opinion.
So I go to my drill index and get a jobber bit that is 0.157 (couldnt find 0.156) and put it under the rib directly in the middle .then hold the ends down against the work bench
So now for the assembly part :
The typical compression board has flat sawn ribs that simply hold the board together and at the end of the glue up/compression process lets say that this imaginary 30 inch rib ends up with a 60 foot radius and about 0.156 inch of available crown - prior to loading with string bearing. My question is how does this rib move under string bearing load if the rib is not designed to support the string bearing load?? Its the board that supports the load in this scenario and the flat sawn rib works against the crown as it wants to go flat.
Just bend a piece of wood and then let it go - it wants to return to its original shape.
Now some compression board designers will buttress the ends of this rib very snugly into the rim of the piano with the intent that the piano rim will not allow it to expand and therefore give support to the string bearing.
Great idea. I believe it has been proven that end grain oriented support like a 4x4 beam that supports a deck or bridge can be stronger than steel.
However, the assumption that the piano rim is absolutely solid and will not move and therefore will not allow this rib to expand under load and therefore retain its sagitta or crown is a little difficult to believe because all of the wood on the entire piano moves and this imaginary rib will move with the rim.
Just how much will the length of this 30 inch rib that has 60 foot radius, with 0.156 inch crown or sagitta under string load change?
My bench test shows that the length of this rib when flat as opposed to when 0.156 inch of crown or sagitta is induced using my jobber bit will change its length by an almost not measurable amount. Possibly only a couple thousandths of an inch or less. I dont have the measuring device that can accurately measure and maybe someone knows the math that can define this change in length. Possibly a variation of the sagitta calc? Im not too good at math.
The piano rim moves that much or more, I dont care how solid it is, what wood its made of or if there are Mason Hamlin restraints assisting it. This flat sawn rib may or may not retain any string bearing support or crown or sagitta assumed by buttressing the end grain into the inner rim.
Now maybe string bearing support and crown retention are not a priority in this sort of design?


What am I missing?


A lot.
How does one go from professed expert to suddenly a curious student?

I'll try an help you tho. The rib IS designed to hold the load. When Ed says it doesn't directly support the load, this is a misleading statement on his part. Because indirect support by de facto becomes direct support. It's a laminated structure that undergoes a hygroscopic process. Your bench test is a false read because it doesn't take into account woods behavior. A straight rib is not the same as a straight rib with a natural bow for instance. The assumption seems to be that flat ribs are glued on, then the board is glued in flat and expected to crown. In that scenario, you would be correct. But that would be bad bellywork.
\Hope that helps.
-chris







Iv never professed to be expert, that’s another one of your figments.
I’ll take Ed’s word over yours any day.
My bench test is indeed an accurate representation, figments cannot change wood dimensions.
The only help responses like yours give is to confirm my opinion of you.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 01/02/20 04:55 AM
A true professed expert would also remain a true student. They are not mutually exclusive. It is a distortion of logic to posit like that. Reminds me of the simpletons who make a fabulous living as talking heads on the media with all their "balanced and fair" pablum.

I must admit it has proven to be a successful business plan. One must never overestimate the intelligence of a group of people who decide believing in a "truth" is more important than knowing what truth is or isn't.
The contradictions are endless
From this:
"I do have much experience with the problems with compression crowned boards and if you re-read my posts, my criticisms are based on that process".

To this?
"I am however interested in flat sawn rib designs coupled with a compression designed board and could stand to be enlightened"

Thats a figment? Okay whatever.

Regarding the two type of systems, I just don't think you can approach a floor joist and a vibrating membrane in the same way. Some of my students came over today and we were discussing what changes I would make to The 7' tall upright I built 10 years ago. At the time, i semi relied on Wolfenden and an article from the journal on selecting rib dimensions. In hindsight, the rib scale is not to my liking, and making a few changes in the piano is possible. Pretty cool stuff. A few special thumb planes perhaps for the tight quarters.
-chris
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/02/20 02:34 PM
Well, could you make a recording, before and after, so we can hear also. "for learning" maybe.

And most importantly! why you are going to do these changes.

Oh and you never fail to mention how the original materials are no good.
That is denial big time.
It is not insulting, It is ignorant.

Maybe your big upright will sound good after the adjustment.

R. Blais.
Thank you for the questions,
I don't know how a recording can capture the experience of what a piano sounds like at the keyboard and simultaneously its projection across the room. Projection seems to be the big gain with the principles and experiments i have discussed. There is a certain piano sound that i like, and when I came across a few of those rare birds, I tore them apart and worked backwards into the design to determine the distinguishing characteristics.

I will refer you to this article of ignorance regarding material science.
https://en.wikipedia.org/wiki/Fatigue_(material)

Also, there are plenty of videos in which blind tests of comparison clearly show that old aged wood has no perceived tonal advantages over new wood among professional musicians who have cultured ears.

With new wood there is a bit of control between tree - kiln - shop. When you add a hundred years of unknown variables to that equation, it at the very least becomes riskier to use..

The big piano sounds fantastic now I assure you. i plan on having pianists make professional recordings on it once my showroom is finished.
But that's another story.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/02/20 04:08 PM
Chris
My experience with compression crowned boards is limited to working with a functional piano that has one, trying to get it to sound good, compensating for flaws in the board by voicing, adding riblets, adding weights etc etc etc and maybe replacing them with my idea of a more controllable system. iv never designed and built and installed a compression board. It don’t take much thinking to figure out that being curious about the ribbing of one of these is desirable.
And your without contradiction I suppose, an authority on clear thinking?
Gene,
Fair enough.
Regarding the ribbing in compression boards here are some things I found. First, there are no two rib scales alike. Even on the same model. The lengths don't coincide with the volumes. Which is quite odd. You would think that the longest rib would also be the largest rib. Some rib scales vary in dimensions, and some don't. Some have low rib counts, others have excessive rib counts. You also see a lot of copying from one manufacturer to another. I recently found a Baldwin that copied a Steinway Rib scale but altered two ribs in the treble section. I presume to address the killer octave problem. Out of 200 scales in my database only 2 appeared to be engineered. At the very least, if controlling stiffness is important, the scales would look very different than they do. So just like string scales that are riddled with errors and can be smoothed out, so its the same with rib scales. I have observed that when I smooth out a rib scale, and proportion the volume to match the length curve, use the correct rib count, riblets are totally unneccessary.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/02/20 05:25 PM
Originally Posted by Chernobieff Piano
Gene,
Fair enough.
Regarding the ribbing in compression boards here are some things I found. First, there are no two rib scales alike. Even on the same model. The lengths don't coincide with the volumes. Which is quite odd. You would think that the longest rib would also be the largest rib. Some rib scales vary in dimensions, and some don't. Some have low rib counts, others have excessive rib counts. You also see a lot of copying from one manufacturer to another. I recently found a Baldwin that copied a Steinway Rib scale but altered two ribs in the treble section. I presume to address the killer octave problem. Out of 200 scales in my database only 2 appeared to be engineered. At the very least, if controlling stiffness is important, the scales would look very different than they do. So just like string scales that are riddled with errors and can be smoothed out, so its the same with rib scales. I have observed that when I smooth out a rib scale, and proportion the volume to match the length curve, use the correct rib count, riblets are totally unneccessary.
-chris


Thank you.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/02/20 05:29 PM
We read the metal fatigue thing? Has zero application for understanding wood.
Steel isn't hygroscopic, and does not change with age, only temperature.

Which two scales were the ones seemingly correct, or is that proprietary info?
Amazing how no one asks me any questions ever.

R.Blais.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/02/20 05:40 PM
All the problems with SB construction now days is because the material "wood" is not properly prepared before,"SEASONING"
One ca him-haw and deny, and call it hogwash, and there seem to be no shortage of naysayers! who insists that aged wood is not as good. Isn't it ignorance to not want to learn.
R.Blais.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/02/20 05:48 PM
Any soundboard design that doesn't take into account compression set has not been completely thought through. Compression set is a very real phenomenon in wood, and has been understood, documented, and recognized for many decades. In a soundboard design, it can be the limiting factor in terms of expected performance over time. BTW, this is a general comment and is not aimed at any particular poster(s).
On the contrary compression set has been completely thought out. As Ed McM stated, the soundboard is an expansion joint. And just because a compression soundboard uses compression as a means to develop stiffness, does not mean it has suffered from compression set. That's a big assumption on your part. Here's your hurdles for burden of proof: 1) you have to know on every board that has failed what the installation moisture content was, 2) then you have to know what Humidity cycles it went through in order to claim compression set was the cause. I have seen Zero data that states the installation MC, and then plotted the life of a piano that went through high humidity swings and document the resultant damage.
I propose that the most likely scenario is a high MC install and the piano living in dry conditions as the most likely cause of cracked boards. And also as stated by ED, the RC&S boards with their minimal expansion joints, have a higher likelihood of being the horribly cracked boards of the future.
-chris
Posted By: WilliamTruitt Re: "Oilcanning" Soundboard Skeptic - 01/02/20 06:46 PM
About 1 1/2 years ago, I visited Craig Hair's shop with my New Hampshire Chapter of PTG (if memory serves me, I believe Peter Grey was there). We saw how he does things and then listened to a rebuilt broad bellied 6'4 " Chickering. To bend a phrase, "I believed my lying ears....". It had a big and vigorous sound, strong from bottom to top (imagine that, a Chickering with volume and sustain in the treble). It had everything that a healthy soundboard has.

I also believe that such a thing as compression set exists in old soundboards.

So what gives in this seeming contradiction?

I think the answer is likely twofold. One, there is likely far less lumber in a panel that has compression set. How much, I cannot say. I doubt anyone else can say either. My sense is that it is likely far less of an issue than we believe.

Craig and I both live in Northern New England, a famously harsh environment for pianos. All those decades of these boards yo-yoing through large humidity swings take their toll and boards flatten out, lose compression and stiffness. We get that tired old board.

So someone like Craig removes the board non-destructively, removes the ribs and bridges, makes repairs to the panel, and then re-ribs the board via compression crowning using either new ribs or the original ones. And gets a very successful result by any standard. That is the second and perhaps most important part.

When you consider the sorry state of our forests these days, with lumber of ever poorer quality and less of it, something has to give. Craig works on many pianos that are old enough to have used old growth lumber from very large and mature trees. There is almost none of that lumber left for modern makers and rebuilders to use. If such lumber already exists in the piano that you have and is viable, why not re-purpose it? And why take more from an already scarce resource when we have other alternatives?. Craig has spent a couple of decades honing his methods.

Could it just be that Craig and Richard Blaisdell are in the vanguard, looking at the rest of us in the rear view mirror?.

That day, listening to their pianos, I thought that maybe my world is a little bigger place than I had thought. That's nice to know.

- Will Truitt

Craig,
Just because wood is Hygroscopic doesn't mean its immune to fatigue.

I'll amend that a little, I found 3 Rib scales that look engineered A 7'4" Weber and a 7' Decker brothers from the 1890's. And a Charles Stieff Upright 1905. All of them went to a low Height profile and the volumes matched the length curves and were proportioned with thought and accuracy. I also had come across a second Stieff upright that was not. I later discoved that One was made by the superintendent/designer Jacob Gross and the other was after he was gone.

When you talk about wood seasoning, are you talking about the resin content??

-chris
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/02/20 09:23 PM
Hello Will, we have never put in new ribs
.
Chris,The resin is still there, It is oxidation of resin and it takes time, years, with atmospheric pressure variances.
The wood breathes in and out high pressure, low pressure, over and over, with every storm, carries in "oxygen". slowly, too slow for most!, soft wood is faster than hard maple. that takes ten years, anyway?
Imagine trying to keep thousands of board feet of lumber, for years, not here! they come around and tax your inventory on the value, every year. Violin makers have to hide the wood. It is too bad.

Roy, I never said there is no compression distortion "set", but I never found crushed cells, and if you do, let me know, I would like to see them. Darn it! seasoning is were the engineering you talk about began, once upon a time, right after cutting.
On with the chase!
R.Blais.
Posted By: ando Re: "Oilcanning" Soundboard Skeptic - 01/03/20 01:34 AM
Just curious, but who is "R Blais", as distinct from Craig Hair? It's a bit confusing because I always thought we were talking to Craig.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/03/20 12:35 PM
I am his business partner. 32 years.
You must not be paying attention because I sign my name every time, for years.
R. Blais.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/03/20 01:52 PM
OK, For those who care, Google this. Properties of aged tone wood japan studies. There is some info there.
R.Blais.
Several years ago, I was fortunate to have 3 Bush and Gertz uprights. The exact model.
In one, I put a Sitka Spruce soundboard with Sitka Spruce ribs.
The second, I put Red Cedar with Sitka Spruce ribs from NW Specialty Woods.
The third, I put Douglas Fir with Douglas Fir ribs.
Ronsen Hammers in all three. Mapes bass strings in all three.

The Spruce BG sounded as expected. The Cedar BG sounded more open. The Douglas Fir BG sounded tighter. All three sounded excellent, and unless told, no one would guess the different species. These were just subtle changes in timbre.
If I had a choice, I would personally lean towards using cedar for soundboards over Spruce because I liked the sound it produced. The only problem would be public acceptance. But tonally, its fantastic imo.
The common denominator is that all three were professionally installed. If any one of them were poorly installed, the result would be poor.

-chris
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/03/20 08:19 PM
Soundboard failure due to compression set is well documented. You don't have to look for crushed cells. Obviously, a number of factors determine the likelihood of compression-set failure in a particular soundboard design, but to deny its existence is to deny reality. Anyone can search and read about what percentage of cross-grain compression will lead to failure. BTW, I did investigate the link referenced by Craig Hair. Here is a quote from the referenced study,
"Although aged wood appeared more rigid and stronger than recent wood, after density and humidity corrections were applied no significant variation of L and R rigidity or L strength was observed. The post-linear behaviour, however, was drastically influenced by wood age especially in R direction where the strength and rupture energy decreased markedly with the time elapsed since the wood was processed. Well-preserved aged wood can be considered as safe as long as it is not loaded perpendicular to grain. "
The study specifically recommends NOT using old wood where it will be subject to cross-grain loading. Hmmmmm.
Posted By: ando Re: "Oilcanning" Soundboard Skeptic - 01/03/20 09:02 PM
Originally Posted by Craig Hair
I am his business partner. 32 years.
You must not be paying attention because I sign my name every time, for years.
R. Blais.

This snide response is not a good reflection on you.
Originally Posted by Roy123
Soundboard failure due to compression set is well documented. You don't have to look for crushed cells. Obviously, a number of factors determine the likelihood of compression-set failure in a particular soundboard design, but to deny its existence is to deny reality. Anyone can search and read about what percentage of cross-grain compression will lead to failure.


Well Documented?? And you don't cite any sources???

And there is compression set without any crushed cells??? Perhaps an explanation?

No one denies the existence of compression set, just it's applicability and proof of causation.

-chris
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/04/20 12:36 PM
Originally Posted by Chernobieff Piano
Originally Posted by Roy123
Soundboard failure due to compression set is well documented. You don't have to look for crushed cells. Obviously, a number of factors determine the likelihood of compression-set failure in a particular soundboard design, but to deny its existence is to deny reality. Anyone can search and read about what percentage of cross-grain compression will lead to failure.


Well Documented?? And you don't cite any sources???

And there is compression set without any crushed cells??? Perhaps an explanation?

No one denies the existence of compression set, just it's applicability and proof of causation.

-chris



I previously cited sources, cross-grain compression set in wood is a well-known phenomenon, and I have neither the time nor the will to spend my time documenting what's already been well documented. If compression set effectively reduces the cross-grain width of the panel in a compression-crowned board by a small percentage*, it would largely eliminate the stress between the board and the ribs, which created the additional stiffness touted by advocates of compression-crowned boards. However, would a wood cell whose width was reduced by a few percent be called crushed? Would anyone identify it as such? The word crushed usually connotes severe deformation. That's why I think the idea of finding crushed cells makes no sense at all.

*The way one would have to measure this would be to measure the cross-grain dimension of the soundboard panel at normal moisture content before ribs were installed, and then remeasure the panel at some point in time when compression set was suspected, after the ribs were carefully removed, and at the same moisture content.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/04/20 01:39 PM
OK--I relented a bit and send these 2 posts, both from Del Frandich. I think the key takeaway is, how much cross-grain compression does a particular soundboard have? 1% or more may well lead to premature failure.

One difficulty with wood – especially a softwood such as
spruce – as a soundboard material is that it is not at all
good at resisting compression across-grain. Wood fibers,
regardless of species, are only capable of withstanding even
short-term compression levels up to approximately one
percent without sustaining some damage. Even at this
relatively low level of compression, damage in the form of
compression set will occur if the compression level is
maintained over a long period of time. In the compression-
crowned soundboard panel the compression level
frequently goes well above two percent (assuming the
relative humidity in the air surrounding the piano gets high
enough – and it often does) so it shouldn't surprise us that
the wood fibers in soundboard panels inevitably end up
exhibiting various signs of compression damage. Once
wood fibers have been damaged by compression there is
nothing we can do to reverse that damage.1Sometimes soundboard compression damage is visible
to the naked eye in the form of compression ridges and the
resulting visible cracks. Often, though, fiber compression
damage is not itself readily visible but its effect can easily be
seen. Wood fibers that have been deformed by compression
no longer have the capability of developing the stress
interface against the ribs required to form and/or sustain
soundboard crown, especially crown that must work against
string downforce.



This question always seems to bring out absolute answers. Reality is somewhat less than absolute.

The problem is that there are several distinctly different ways to design and construct soundboard systems. One system, what I call compression-crowning, depends of a relatively high amount of perpendicular-to-grain compression within the spruce panel both to initially form and subsequently maintain crown. The other depends on a curve machined (or otherwise formed) along the surface of the rib to form and maintain crown. I call these soundboard systems , rib-crowned., Both systems have their fans and supporters.

To complicate matters many pianos have been (and are being) built using what I call hybrid-crowning. That is, the ribs are crowned a little bit, usually not as much as they would be for a pure rib-crowned system, and the soundboard panel is dried a little bit, usually not as much as it would be for a pure compression-crowned system.

Neither the pure rib-crowned soundboard systems nor the hybrid-crowned systems present much of a problem. Yes, they do develop cracks on occasion, but they do not generally deteriorate in ways that cause acoustical, or tone performance, problems.

If the original soundboard system was built using the compression-crowning technique it will be particularly susceptible to compression damage. These boards are quite prone to cracking and the cracks are prima fascia of catastrophic soundboard failure. By this, I mean that the cracks are strong evidence that the musical potential of the soundboard system has been fatally impaired. Tonal evidence will usually be present in the form of a relatively percussive tone having a rapid drop-off and short sustain times particularly through the upper third of the scale. It is pianos with these soundboard systems that gave meaning to the phrase, killer octave. This refers to a span of roughly an octave or an octave and a half usually centered somewhere around the fifth or sixth octave.

So, when a piano that was built with a compression-crowned starts to develop cracks, and sooner or later they almost all will, is this really the kiss of death? The answer is definitely, absolutely maybe, or maybe not! The proof will be in the performance of the piano. If the piano has developed the dreaded killer octave syndrome then yes, the wood in the soundboard panel has been irreversibly damaged.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/04/20 03:15 PM
Well, Hmmmmm, then I guess I should just give up and send the last 30 pianos we did out for new boards. Because of what most say.

Ok, Roy, Take a good look at our atwood O No. 73 or SB walk around 1&2 U tube videos. and pleas ask some questions.
I f we had problems with the killer spot we would have stopped long ago.
There is some distortion on these real old sb's but not to the extreme everyone seems to think, we discovered!.
By taking them out and putting them back in we leaned much.
Here's something, after ribs and bridges are off, the panel is heated past the melting point of the resin content, and this allows the wood to re dimension, "gets smaller", after which it stays put. otherwise it cannot be worked with.

R.Blais.
Posted By: Ed McMorrow, RPT Re: "Oilcanning" Soundboard Skeptic - 01/04/20 03:52 PM
Invoking the "Killer Octave" to claim SB death is a risky diagnosis. I have worked on many a piano that has been declared "treble dead" by Technicians under the severe influence of compression set syndrome.

Upon solving existing problems like V-bar shape, strike point, and especially applying LightHammer Tone Regulation; the "Killer Octave" suddenly has life!

I am not contesting compression set existence or dangers, just tonal significance.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/04/20 04:19 PM


Here's something, after ribs and bridges are off, the panel is heated past the melting point of the resin content, and this allows the wood to re dimension, "gets smaller", after which it stays put. otherwise it cannot be worked with.

R.Blais.
[/quote]

A friend of my partner has been talking about an idea that would remove these resins from new wood prior to assembly using some sort of chemical bath.
Got to find out more about this.
You ever heard of such a process??
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/04/20 04:36 PM
Originally Posted by Craig Hair
Well, Hmmmmm, then I guess I should just give up and send the last 30 pianos we did out for new boards. Because of what most say.

Ok, Roy, Take a good look at our atwood O No. 73 or SB walk around 1&2 U tube videos. and pleas ask some questions.
I f we had problems with the killer spot we would have stopped long ago.
There is some distortion on these real old sb's but not to the extreme everyone seems to think, we discovered!.
By taking them out and putting them back in we leaned much.
Here's something, after ribs and bridges are off, the panel is heated past the melting point of the resin content, and this allows the wood to re dimension, "gets smaller", after which it stays put. otherwise it cannot be worked with.

R.Blais.

I can find no references to heating wood to "melt the resin content," and, in fact, don't even know what that really means. Which of the wood's constituent components are melting? Wood is largely cellulose, but there are a fair number of other chemicals in wood, of course. To what temperature do you heat the wood? Can you provide any links, references, or other information? Your Youtube videos were perhaps made shortly after you remanufactured the soundboards. Is that the case? If so, they may not be predictive of the soundboards' condition 10 years later. I keep thinking back to the fact that 1% or higher cross-grain compression of wood will often, or perhaps most often, lead to compression set. Perhaps your methodology does not exceed that value. Perhaps you use some kind of hybrid method of crowning. Without that information, I can't really intelligently comment on your claims.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/04/20 07:05 PM
Originally Posted by Ed McMorrow, RPT
Invoking the "Killer Octave" to claim SB death is a risky diagnosis. I have worked on many a piano that has been declared "treble dead" by Technicians under the severe influence of compression set syndrome.

Upon solving existing problems like V-bar shape, strike point, and especially applying LightHammer Tone Regulation; the "Killer Octave" suddenly has life!

I am not contesting compression set existence or dangers, just tonal significance.


This is interesting and Ill relate my experience:
In June of 2008 I took classes at the PTG convention in Anaheim Ca - from you Ed as well as Steve Brady.
At the end of each class I purchsede your books.
I still have them today and refer to them regularly and they are most valuable to me.
When the opportunity opened up for me to get into concert work in 2011, if I did not have these books there is no way that I would have survived very long doing concert level work. Not taking anything away from my partners help too.
That said, there still exists a question of weather all of the things that can be done to make the killed killer octave sound great are compensations for a failed soundboard or work that should have been done before the piano left the showroom or factory???
Ill stick with the failed soundboard.
But I believe there will remain a dichotomy.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/04/20 11:32 PM
Originally Posted by Gene Nelson
Originally Posted by Ed McMorrow, RPT
Invoking the "Killer Octave" to claim SB death is a risky diagnosis. I have worked on many a piano that has been declared "treble dead" by Technicians under the severe influence of compression set syndrome.

Upon solving existing problems like V-bar shape, strike point, and especially applying LightHammer Tone Regulation; the "Killer Octave" suddenly has life!

I am not contesting compression set existence or dangers, just tonal significance.


This is interesting and Ill relate my experience:
In June of 2008 I took classes at the PTG convention in Anaheim Ca - from you Ed as well as Steve Brady.
At the end of each class I purchsede your books.
I still have them today and refer to them regularly and they are most valuable to me.
When the opportunity opened up for me to get into concert work in 2011, if I did not have these books there is no way that I would have survived very long doing concert level work. Not taking anything away from my partners help too.
That said, there still exists a question of weather all of the things that can be done to make the killed killer octave sound great are compensations for a failed soundboard or work that should have been done before the piano left the showroom or factory???
Ill stick with the failed soundboard.
But I believe there will remain a dichotomy.


I’ll add that the majority of concert pianos I’ve encountered have this sort of problem. It includes not just the typical New York piano that graces most venues but a couple very expensive hand made German pianos as well. All have compression crowning in common.
Dead areas especially but not limited to the killer octave that coincide with zero string bearing.
We had our resident principal pianist go to New York and select a 7 ft piano. Good even tone and power were easy to develop by simple voicing and regulation.
It lasted about 3 years. Bearing disappears and tone sustain deadens from about A-4 to A-6
Posted By: OE1FEU Re: "Oilcanning" Soundboard Skeptic - 01/05/20 12:53 AM
Originally Posted by Ed McMorrow, RPT


Upon solving existing problems like V-bar shape, strike point, and especially applying LightHammer Tone Regulation; the "Killer Octave" suddenly has life!


This.
Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/05/20 02:15 PM
Originally Posted by Ed McMorrow, RPT
Invoking the "Killer Octave" to claim SB death is a risky diagnosis. I have worked on many a piano that has been declared "treble dead" by Technicians under the severe influence of compression set syndrome.

Upon solving existing problems like V-bar shape, strike point, and especially applying LightHammer Tone Regulation; the "Killer Octave" suddenly has life!

I am not contesting compression set existence or dangers, just tonal significance.


I think it's fair to say that Ed is suggesting a number of possible reasons for the so-called killer octave problem, or "treble death" as he described it. I think we could all agree with that. Pianos are subtle and complex instruments and no doubt many tonal problems could have multiply causes.
Originally Posted by Gene Nelson


Here's something, after ribs and bridges are off, the panel is heated past the melting point of the resin content, and this allows the wood to re dimension, "gets smaller", after which it stays put. otherwise it cannot be worked with.

R.Blais.


A friend of my partner has been talking about an idea that would remove these resins from new wood prior to assembly using some sort of chemical bath.
Got to find out more about this.
You ever heard of such a process??[/quote]


Stated like this is a new idea??
I would refer you way back to 1871, in which John B. Dunham invented a process that does that very thing except chemicals are not needed. He called his process hydro-carbonization. I've been playing with this on and off as it is claimed to make wood no longer susceptible to humidity changes. A bold claim but Dunham was a very respected piano builder.
Posted By: Craig Hair Re: "Oilcanning" Soundboard Skeptic - 01/05/20 03:59 PM
Hello Roy, Well one example would be when a maple hammer shank is heated hot, and can be twisted straight, and can actually go too far. Now what is happening?
We did an 1895 Model B, in 1989, it is in a local venue, SB is still good.
R. Blais
Roy123,

I was expecting like a botany expert, maybe a USFS document (since there are thousands), or wood species experts, mechanical engineer lab reports. You know, something scientific. Instead you cite (in this case) a biased piano technician who's perhaps the strongest proponent of RC&S? That's hardly convincing. I was hoping for a real article that explains the compression set process? And how it was tested? BTW, Hoadley would also be a poor reference to cite because when he was later shown how compression soundboards were made. His reply -" I didn't know wood could do that."

Also, I don't get your 1% standard. My understanding is that the difference between Compression crowning and RC&S crowning is 1%. The compression method install EMC% is 4%, and the RC&S install EMC% is 5% (according to RC&S authors i have come across). For the average room RH% (70F, 50%RH which equates to 9%Emc) that is a 4 and 5 % difference. So both according to your standard would fail.

A large error in assumption you are making is the belief that the compression crowning method is at fault for the Killer Octave problem. Am I mistaken when I say that I only hear Techs talk of a Steinway Killer octave problem? What about MH or Baldwin? I have studied the soundboards of all three in detail. The MH and Baldwins have thicker panels and taller ribs than SS. The Steinway diaphragmatic boards have severe weaknesses in the treble due to a panel being 1/4" in the treble and often ribs that are 5/8"- 1/2" tall in the treble. And they are often coupled with a steep downbearing angle of 2 degrees in the treble. This is not a good combination.

Plus, the position of your argument is weak and unnatural. It is equivalent to saying " rubber is bad for tires because they only last 50,000 miles" "Concrete is bad for buildings because it weakens and crumbles in a 100 years" It's actually quite an amazing feat that compression boards last the decades they do when compared to other items that fatigue and disintegrate over time.
What matters is how they perform during that time, and that is were the CC boards have excelled, when you go by the top piano brands that use them, and the top elite pianists that pick them.

-chris

Posted By: Roy123 Re: "Oilcanning" Soundboard Skeptic - 01/06/20 12:33 AM
Originally Posted by Chernobieff Piano
Roy123,

I was expecting like a botany expert, maybe a USFS document (since there are thousands), or wood species experts, mechanical engineer lab reports. You know, something scientific. Instead you cite (in this case) a biased piano technician who's perhaps the strongest proponent of RC&S? That's hardly convincing. I was hoping for a real article that explains the compression set process? And how it was tested? BTW, Hoadley would also be a poor reference to cite because when he was later shown how compression soundboards were made. His reply -" I didn't know wood could do that."

Also, I don't get your 1% standard. My understanding is that the difference between Compression crowning and RC&S crowning is 1%. The compression method install EMC% is 4%, and the RC&S install EMC% is 5% (according to RC&S authors i have come across). For the average room RH% (70F, 50%RH which equates to 9%Emc) that is a 4 and 5 % difference. So both according to your standard would fail.

A large error in assumption you are making is the belief that the compression crowning method is at fault for the Killer Octave problem. Am I mistaken when I say that I only hear Techs talk of a Steinway Killer octave problem? What about MH or Baldwin? I have studied the soundboards of all three in detail. The MH and Baldwins have thicker panels and taller ribs than SS. The Steinway diaphragmatic boards have severe weaknesses in the treble due to a panel being 1/4" in the treble and often ribs that are 5/8"- 1/2" tall in the treble. And they are often coupled with a steep downbearing angle of 2 degrees in the treble. This is not a good combination.

Plus, the position of your argument is weak and unnatural. It is equivalent to saying " rubber is bad for tires because they only last 50,000 miles" "Concrete is bad for buildings because it weakens and crumbles in a 100 years" It's actually quite an amazing feat that compression boards last the decades they do when compared to other items that fatigue and disintegrate over time.
What matters is how they perform during that time, and that is were the CC boards have excelled, when you go by the top piano brands that use them, and the top elite pianists that pick them.

-chris

Good grief--where to begin. As I previously said, I really don't need to spend my time doing a research project. If I had free access to Hoadley, then I might convince myself to crack it open.
First, the idea that Hoadley would be a poor reference over something he supposedly said is ridiculous. Who knows if the quote is apocryphal, and who knows to what he was referring. Maybe he hadn't been exposed to compression-crowned SBs, and was making an off-hand comment about the curvature. What matters is his research and testing. In terms of Del's posts being convincing, what matters is what testing he has done, and what the results were of his tests. The evidence he has written about, I have found quite convincing. Secondly, rib-crowned boards don't require any difference in moisture content between ribs and panel. Perhaps, the information you cited was for hybrid boards. You shouldn't make the assumption that RC boards are universally made according to the information you mentioned. Thirdly, I was making the point that failures of CC boards due to compression set have been observed many times, and tests have shown why such a failure could heppen. I was not making any specific claim about the killer octave, and, in fact, I made a specific statement in response to one of Ed's posts that killer octave failure probably has any number possible causes. Fifth, your comment, "Plus, the position of your argument is weak and unnatural. It is equivalent to saying " rubber is bad for tires because they only last 50,000 miles" " is so strange I'm not sure how to respond to it. From my reading, some CC boards fail rapidly, and some last quite a long time, for reasons that may be somewhat poorly understood.
Finally, the use of CC boards by top brands and especially Steinway is a poor example. Steinway, as a company, is loath to change its designs, in part because of its marketing hype. It was reported that one of the owners once said something along the line of, "We perfected the piano in the 1930s, and now all we need to do is to make them as good as possible." I think everyone will acknowledge that when a CC board works well, it can function very well, indeed. The only point I have been trying to make is that history, theory, and testing show that cross-grain compression set in CC boards can cause premature failure, and the possibility of such failure is supported by evidence and the analysis of wood. I am not trying to make an absolute point, saying that ALL CC boards will experience premature failure, but as far as I can tell, it is you making the absolute claim that CC boards NEVER experience failure due to cross-grain compression set in the panel.
I have no more to say.

Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/06/20 02:17 AM
Don’t know the difference between elite or performing artists but they choose Steinway for several reasons.
The main reason in my experience is availability coupled with the Steinway Artist signed contract.
Performers will not perform on a different piano because of the consequence of losing that availability.
It has nothing to do with the quality of the instrument being performed on.
Talk to them and watch them perform and you find that their technique must be adaptable to the very problems highlighted in this thread in regard to compression boards. They never know what to expect as not all pianos have had a professional tech apply the fixes and adaptations that help the dead areas of the board.
They complain about the same things, lack of sustain and power in the killer octave.
Some pianos have been made more presentable.
And this is only half of the complaints.
We haven’t even addressed action problems.


Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/29/20 12:56 AM
Originally Posted by Gene Nelson
I recently removed a board from a small SS
Prior to removal with strings on and up to pitch there was very slight (almost not measurable) bearing in the treble, everywhere else zero.
There was zero crown on the board - used straight edge to detect.
The board was not inverted, it was as flat as my straight edge.
Now after sitting for a couple months (out of the piano) the board is very inverted - or oil caned.
Scratches head wondering why it didn’t revert and give some positive crown?? Why negative???
My assumption is the board suffered compression set, failed, lost any support capability it may have had and the ribs now dominate the shape of the assembly.
Why flat sawn ribs would move in the opposite direction I could only guess but it does suggest that this sort of design has an undesired effect of working against crown.


Well here’s more oil can stuff:
Mild weather here and rainy, relative humidity around 90% and this board now has positive crown.
This change compares with a lower humidity higher temp in early December when this all started and the board was inverted.
It confirms my idea that the board has been previously destroyed by compression set but the ribs have not and the ribs now dominate the shape of the board because of the damage.
Also, thinking back to when it was in the piano and strings were on and up to pitch and the board was dead flat. Then it’s reasonable that the strings dominated the shape of the dead structure.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 01/29/20 01:31 AM
I could agree with that.

Pwg
I don't. All of Gene's reasoning is based on assumptions. He hasn't proven the cause to attribute the correct effect.
For example- How about a photo of the compression set cell structure? On first removal and then later at positive crown. Did the Cells actually restore themselves or were they ruptured. You know, so that compression set is actually established. What was the install procedure? What was the install humidity and temp? Maybe some real scientific evidence. Instead of assumptions would be nice.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/29/20 05:57 AM
Chris, your funny.
The board moves the way I said it moves.
Compression set is the reason.
If I gave you what you demand it would not be enough and you know it.
Compression boards tend to be failures right out of the shop.
By the way, I did put some sand on the thing, pounded it and got a circle pattern in the middle.
Confirmation of failure.
Brawndo, It's what plants crave! It's got electrolytes.

In essence, that's the answer you just gave.

And dispense with the mine reading cause you're horrible at it.

I just simply asked for proof. Like a micron pictograph with a description of the conditions of the sample when it was taken.
You described a sequence of events. So then a series of pictographs along with the descriptive conditions to explain the sequences. That way your statements could be verified. As it stands your statements are unverifiable and remain assumptions. In other words guesses.

BTW, Sand and fist pounding doesn't work. You need a sine wave generator.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 01/29/20 02:44 PM
You “simply” ask me to provide a micron photograph.
Your funny Chris.
Your needs have little meaning for me, sorry.
My opinions and observations are valid regardless of your ravings.
You’ll just have to continue to whine about how wrong I am with less than desired response.
Originally Posted by Gene Nelson
You “simply” ask me to provide a micron photograph.
Your funny Chris.
Your needs have little meaning for me, sorry.
My opinions and observations are valid regardless of your ravings.
You’ll just have to continue to whine about how wrong I am with less than desired response.


1) Thanks
2) Likewise
3) Unverified
4) Projection
Fact: The proportional Limit of Spruce's compression strength perpendicular to the grain is 580 p.s.i
Up until that point it keeps its elasticity.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/02/20 07:23 PM
sounds very strong.
however, when figuring how that 580 lbs could be applied it paints a different picture.
It is not a collective value.
In other words it is to the individual cell
when you consider the diameter of a typical cell is in the nanometer range - that is 9 zeros on the other side of the decimal point -
then find the surface area of a cell based on that number and then factor it into 580 lbs per square inch, all of a sudden it presents a weakness.
It really dont take much to rupture that cell.
maybe someone with a science background knows how this 580 psi is applied?
I wish you would take the time to understand the material you are working with. In this case, its the understanding of the stress strain curve. The proportional limit is not the M.O.R. so rupture is not even a concern yet.
-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/02/20 11:40 PM
Chris
Compression set happens. Get over it.
And yeah, I don’t understand anything about Sitka.
Originally Posted by Gene Nelson
Chris
Compression set happens. .

How do you know? you've presented no facts. And even pleaded for a scientist to step in. What a joke.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/03/20 04:10 PM
Every experience/observation I made in this thread is proof enough that compression set happens.
I’m sorry that you don’t approve or it’s not enough for you.
Dealing with defective compression soundboards is a reality Chris, I’m a technician, not a scientist and don’t mistake my request for information as pleading, that’s being very immature.
Many compression boards are defective on the showroom floor, direct from the factory.
It’s no joke.
It’s especially no joke when a client realizes this soon after spending a fortune on one of these failures.
You defend them because you build them, understandable.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/03/20 04:24 PM
By the way
My oil canning board is on the move again - dead flat right now.
If the design had any integrity at all it would be observable.
What is observable is failure of design, compression set at is best, oil canning in relation to ambient conditions.
Not quite what the OP had in mind but it’s certainly descriptive of my observation and it’s reasonable to assume similar behavior of these things while part of an intact instrument.
See Gene,
Listen, And i'll state it plainly for you.. Your assessments cannot be taken seriously because you have no idea whatsoever of the install conditions.

-chris
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/03/20 11:03 PM
Originally Posted by Chernobieff Piano
See Gene,
Listen, And i'll state it plainly for you.. Your assessments cannot be taken seriously because you have no idea whatsoever of the install conditions.

-chris


Something unique to a typical SS install?
Maybe it was a bad day in New York eh?
And I’ll state it plainly to you: this oil can of a soundboard and how it is moving in response to changing environmental conditions is not an assessment, it is a direct observation. Very scientific, very factual.
We do have something in common:
I don’t take anything you say seriously as well.

Have you considered trying to answer the OP’s question yet?
This entire exchange between you and I is all about you not liking my answer to his question.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/04/20 06:30 PM
Never mind the OP's OQ. I haven't seen where any of you really understand how an oil can works - but that's not really important at all any more, at least to me. I have been able to decide a thing or two that I will not share.

Here's something that may help, or at least make more entertaining, the present, er, discussion: What about compression ridges? Is it possible to have them without overcoming the reversible compression limit (or whatever it might be called)? Or are compression ridges a misnomer for something else?
There are two things going on that must be explained for clarity.
1)Wood Behaviour
2)Manufacturing processes.

1)A simple place to start in understanding wood behaviour (in this case Transverse Radial Compression) is looking at the stress strain chart. A lot of things have to happen before there is structural damage. Elasticity, plasticity, densification, and rupture. Between elasticity and plasticity is the proportional limit. This means that in the elastic zone stress and strain are in proportion, and in the plastic zone they are not in proportion. I suspect than when wood reaches plasticity in soundboards via compression, that technicians are calling this "damaged" and say it later becomes a crack. But this is an error, a rupture has to occur. In Hoadleys book he shows a compression test. It has a board bolted between two steel beams. He starts at 7% and goes to 12% and back to 7%. A crack develops. The problem is that this does not represent what happens in a soundboard. The soundboard crowns(moves) under that pressure. In effect, relieving the strain.

2) There are many many ways to install a compression soundboard. It can be installed wet, or it can be installed dry. It can be made in an arched press, or a flat press. It can be made thick and heavy, or light in weight. It can even be installed too soon out of the kiln.


So my thoughts on the cause of an "oil canned board" are leaning towards a bad install coupled with a poor rib structure(design) as it relates to the load placed on it. Some boards most likely never crowned properly in the first place, thus the advantage of the arch was never there. Also, Some soundboards have a very heavy downbearing placed on them. So there are a combination of factors that must line up to make a board bad. I have seen many boards a hundred years old. Most are in really bad shape, but there are also ones still in good shape, and even some in great shape that defy their age. I think the ones that were installed correctly and then taken care of are the ones that do well.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/05/20 12:07 PM
I Googled "Transverse Radial Compression". Got 9 original hits. None have anything to do with wood.
Jeff,
Perhaps you can Google "Compression Perpendicular-To-Grain Behaviour of Wood" by Tabarsa.

This is Tabarsa' Doctoral Thesis on Compression and it is his specialty field of study.
Enjoy!
-chris
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/06/20 03:05 AM
Mr. C: I suggest discussing compression ridges. You talk about "Transverse Radial Compression", in capitals like its proper noun or something. I state how it is an obscure term apparently not related to the behavior of wood. You suggest I refer to a Doctoral Thesis you know of. No thanks. I see a slippery slope into a barnyard.
Tooner said,
I suggest discussing compression ridges. You talk about "Transverse Radial Compression", in capitals like its proper noun or something.

It's the same thing tooner.

-chris
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/06/20 10:13 AM
Originally Posted by UnrightTooner
FWIW

I am not an expert on soundboards and never expect to build one or even install one. Just has a question about what you fine folks considered an "oilcanned" soundboard to be because I doubted a soundboard could actually act like the bottom of an oil can.

Anyhoo, the discussion stayed with soundboards with some posters having very different views on the subject. Not knowing all that much myself, I found myself relying on some adages to try to sort out the wheat from the chaff:

If someone is focusing on themselves rather than the subject, they are probable full of it, or at least full of themselves, if there is a difference.

If someone is using typical words in untypical manners, they don't know the words to use, and nobody else can really know what they mean either.

A sure way to spot an abuser is to call them on it. If they become defensive, or offensive, there can be little doubt.

When there are aspects to a subject that can only be experienced, and not analysed, those aspects belong in la-la land.

Someone that fully understands a subject can explain it in clear terms.

A professional, humble person always points out their limits.

If you argue with a fool, people will assume you are a fool, too.


MERRY CHRISTMAS!!!


Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/06/20 02:34 PM
This doesn't seem to be going anywhere.

Pwg
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/06/20 08:46 PM
Originally Posted by P W Grey
This doesn't seem to be going anywhere.

Pwg

I would be a fool to argue with that. wink
Tooner,

Just because you didn't understand the term Transverse Radial Compression is no reason to start name calling. That's hardly fair.
I was just trying to make a contribution based on my expertise. If the post went nowhere, that's not my fault.
-chris
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/07/20 02:16 AM
Originally Posted by Chernobieff Piano
Tooner,

Just because you didn't understand the term Transverse Radial Compression is no reason to start name calling. That's hardly fair.
I was just trying to make a contribution based on my expertise. If the post went nowhere, that's not my fault.
-chris


Please point out where I name called.
Posted By: DoelKees Re: "Oilcanning" Soundboard Skeptic - 02/07/20 02:37 AM
Originally Posted by UnrightTooner
Please point out where I name called.

You called your hypothetical self (the one that would argue that this is going somewhere) a fool. smile

Kees
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/07/20 09:25 AM
Originally Posted by DoelKees
Originally Posted by UnrightTooner
Please point out where I name called.

You called your hypothetical self (the one that would argue that this is going somewhere) a fool. smile

Kees

Is it name calling when one good naturally jests about one's self?

Of course I doubt that is the incident Mr. C is referring to. He seems to be tying it into my not understanding what he meant by an obscure, apparently misused term. But can calling somebody a name caller be name calling? I think so. Seems Mr. C is verbally abusive when others do not bow to his self proclaimed expertise. Allowing such behavior to go unchallenged is not good for anyone, especially Mr. C.
Tooner,
Here are those obscure and apparently misused terms according to the Google dictionary.

Transverse --- situated or extending across something
Radial-----of or arranged like rays or the radii of a circle; diverging in lines from a common center
Compression----the action of compressing or being compressed

Doesn't that just sound like it's simply describing an action in a certain direction?

-chris
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/07/20 08:46 PM
Originally Posted by Chernobieff Piano
Tooner,
Here are those obscure and apparently misused terms according to the Google dictionary.

Transverse --- situated or extending across something
Radial-----of or arranged like rays or the radii of a circle; diverging in lines from a common center
Compression----the action of compressing or being compressed

Doesn't that just sound like it's simply describing an action in a certain direction?

-chris



Sorry, I do not wish to discuss this. Again, No Thanks.
Posted By: HansC2 Re: "Oilcanning" Soundboard Skeptic - 02/08/20 10:40 AM
It is a real pity that some experts that post at PW doesn’t seem to be able to discuss interesting things in a way that it brings new knowledge on the subject. They refuse to listen to each other and to learn from each other. I don’t understand why. I believe real experts show more doubts when discussing things and show a more scientific attitude. I have seen many of the real experts leave the PW arena in the past couple of years. From them I have learned a lot of interesting things.

(Please excuse my bad English)
Posted By: GC13 Re: "Oilcanning" Soundboard Skeptic - 02/08/20 02:24 PM
Originally Posted by HansC2
It is a real pity that some experts that post at PW doesn’t seem to be able to discuss interesting things in a way that it brings new knowledge on the subject. They refuse to listen to each other and to learn from each other. I don’t understand why. I believe real experts show more doubts when discussing things and show a more scientific attitude. I have seen many of the real experts leave the PW arena in the past couple of years. From them I have learned a lot of interesting things.

(Please excuse my bad English)


+1 thumb

We see threads take on this tone between the professionals quite often here on PW! I think it's sad. I wonder if all of you would talk to each other in these tones face to face or over the telephone?! In my professional work as a software, I like to hear from others who come at the the same problems from a different angle. I certainly do run in to individuals whose ideas and methods I take issue with, and I therefore discard their ideas, but quite often I find another way of looking at the same problem, and I find other solutions and methods that I might tuck away for now, but then I'll pull it out later and give it a try. I think about the variations of production methods and designs across all of the piano manufacturers. Many of the most well known and top-tier piano makers use very different materials and differing manufacturing processes, but they still make lovely instruments with their own distinct character. We all tend to have the mindset that our way of doing anything we do in life is the "best way", but it is extremely closed minded to think that our way is THE ONLY WAY! And I have to say, that over the years in different areas of the US, I've found that mindset to be quite prominent among piano technicians in general. I think it's sad.

Over my years here on PW, I've read many, many posts written by all of the professionals who are attacking each other in this thread. I've often thought that I'd love to have the change to play a Baldwin, Bosendorfer, Steinway, M&H, Kawai, or Yamaha restored or prepared by each of you to sample your work and hear it for myself. I can tell that each of you have decades of experience and do concert level work. I would think that would foster a general since of respect and admiration, and an attitude of community and knowledge-sharing. In our area, I have found a nice since of community among the various concert technicians I have worked with. I've really never heard one of them put down another's work. In fact, more often than not, I've heard them praise one another, work together and pool resources on larger projects, and refer work to other other technicians based on the piano make, condition and required work, and material preferences or other specific needs of the client. I find it quite refreshing! It makes me trust a technician even more!
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/08/20 04:20 PM
FWIW, piano tuning is not a social, team building endeavor...
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/08/20 04:25 PM
Or; if a factory is producing a diamond in the rough, why aren’t they producing diamonds?
Posted By: HansC2 Re: "Oilcanning" Soundboard Skeptic - 02/08/20 04:38 PM
Originally Posted by UnrightTooner
FWIW, piano tuning is not a social, team building endeavor...


Well making babies isn’t either, but it is still nice to talk with other parents about children, discuss problems and learn from them...
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/08/20 06:43 PM
Hey Jeff,

How has your personal upright project finally turned out? Still behaving well?

Pwg
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/08/20 09:10 PM
Nice of you to ask! smile I have high hopes, but haven't had time to do much lately. Last thing was to replace the key buttons and I think now I will also replace the balance rail pins. New ones are 1/1000th inch bigger and go with the size of the buttons.

Didn't get as much downbearing in the top handful of notes on the bass bridge as I should have when setting the plate and I can hear it in the thin tone. Gonna do the unthinkable and shim the top of the bridge there (Gasp!). OK here it comes, wait for it:

I doubt crown means much of anything at all on it's own. It's downbearing that is needed.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/08/20 11:53 PM
Please reveal the results when they are in!

A question though: Is it a situation where the low tenor is quite loud but then when transitioning to the bass bridge it all drops off?


Pwg
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/09/20 12:15 AM
Perhaps a little, and the tonal difference isn't strikingly obvious either. Fortunately it is a straight bridge, so doing a shim will not be complicated. 1/16" tapering down to paper thin in about 9 notes. The top bass note is the only one with zero DB.
If it were me--- instead of exacerbating the problem. I would contemplate the phoenix agraffe bridge system. That way it circumvents the downbearing issue.
-chris




Google dictionary:
exacerbate--make (a problem, bad situation, or negative feeling) worse.
circumvent--find a way around (an obstacle).
contemplate--look thoughtfully for a long time at

Links- https://www.phoenixpianos.co.uk/phoenix-bridge-technology/
Posted By: dogperson Re: "Oilcanning" Soundboard Skeptic - 02/09/20 03:06 AM
Originally Posted by GC13
Originally Posted by HansC2
It is a real pity that some experts that post at PW doesn’t seem to be able to discuss interesting things in a way that it brings new knowledge on the subject. They refuse to listen to each other and to learn from each other. I don’t understand why. I believe real experts show more doubts when discussing things and show a more scientific attitude. I have seen many of the real experts leave the PW arena in the past couple of years. From them I have learned a lot of interesting things.

(Please excuse my bad English)


+1 thumb

We see threads take on this tone between the professionals quite often here on PW! I think it's sad. I wonder if all of you would talk to each other in these tones face to face or over the telephone?! In my professional work as a software, I like to hear from others who come at the the same problems from a different angle. I certainly do run in to individuals whose ideas and methods I take issue with, and I therefore discard their ideas, but quite often I find another way of looking at the same problem, and I find other solutions and methods that I might tuck away for now, but then I'll pull it out later and give it a try. I think about the variations of production methods and designs across all of the piano manufacturers. Many of the most well known and top-tier piano makers use very different materials and differing manufacturing processes, but they still make lovely instruments with their own distinct character. We all tend to have the mindset that our way of doing anything we do in life is the "best way", but it is extremely closed minded to think that our way is THE ONLY WAY! And I have to say, that over the years in different areas of the US, I've found that mindset to be quite prominent among piano technicians in general. I think it's sad.

Over my years here on PW, I've read many, many posts written by all of the professionals who are attacking each other in this thread. I've often thought that I'd love to have the change to play a Baldwin, Bosendorfer, Steinway, M&H, Kawai, or Yamaha restored or prepared by each of you to sample your work and hear it for myself. I can tell that each of you have decades of experience and do concert level work. I would think that would foster a general since of respect and admiration, and an attitude of community and knowledge-sharing. In our area, I have found a nice since of community among the various concert technicians I have worked with. I've really never heard one of them put down another's work. In fact, more often than not, I've heard them praise one another, work together and pool resources on larger projects, and refer work to other other technicians based on the piano make, condition and required work, and material preferences or other specific needs of the client. I find it quite refreshing! It makes me trust a technician even more!
.

I’ve spent a lifetime in an industry with highly trained and educated professionals... and the truly great ones never demeaned anyone else. Just sayin’
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/09/20 03:14 PM
I was thinking of adding weight to the back of the tenor bridge, and/or possibly a riblet strategically located to reduce the amplitude of the low tenor notes, thereby easing the transition to the bass. I like starting there because it's a lot easier to do and is also quickly reversible if ineffective. Sometimes a similar treatment can be done at the bass bridge too. A quick experiment is to use mini vise grips on a bridge pin to see if any improvement. I would also consider adding weight to the bass hammers (mini binder clip on shank experiment) since the physical weight of bass hammers is significantly less than the tenor hammers right there. All of which is much easier than shimming the bass bridge for DB.

Just my .02

Pwg
Posted By: HansC2 Re: "Oilcanning" Soundboard Skeptic - 02/09/20 06:46 PM
Originally Posted by dogperson
Originally Posted by GC13
Originally Posted by HansC2
It is a real pity that some experts that post at PW doesn’t seem to be able to discuss interesting things in a way that it brings new knowledge on the subject. They refuse to listen to each other and to learn from each other. I don’t understand why. I believe real experts show more doubts when discussing things and show a more scientific attitude. I have seen many of the real experts leave the PW arena in the past couple of years. From them I have learned a lot of interesting things.

(Please excuse my bad English)


+1 thumb

We see threads take on this tone between the professionals quite often here on PW! I think it's sad. I wonder if all of you would talk to each other in these tones face to face or over the telephone?! In my professional work as a software, I like to hear from others who come at the the same problems from a different angle. I certainly do run in to individuals whose ideas and methods I take issue with, and I therefore discard their ideas, but quite often I find another way of looking at the same problem, and I find other solutions and methods that I might tuck away for now, but then I'll pull it out later and give it a try. I think about the variations of production methods and designs across all of the piano manufacturers. Many of the most well known and top-tier piano makers use very different materials and differing manufacturing processes, but they still make lovely instruments with their own distinct character. We all tend to have the mindset that our way of doing anything we do in life is the "best way", but it is extremely closed minded to think that our way is THE ONLY WAY! And I have to say, that over the years in different areas of the US, I've found that mindset to be quite prominent among piano technicians in general. I think it's sad.

Over my years here on PW, I've read many, many posts written by all of the professionals who are attacking each other in this thread. I've often thought that I'd love to have the change to play a Baldwin, Bosendorfer, Steinway, M&H, Kawai, or Yamaha restored or prepared by each of you to sample your work and hear it for myself. I can tell that each of you have decades of experience and do concert level work. I would think that would foster a general since of respect and admiration, and an attitude of community and knowledge-sharing. In our area, I have found a nice since of community among the various concert technicians I have worked with. I've really never heard one of them put down another's work. In fact, more often than not, I've heard them praise one another, work together and pool resources on larger projects, and refer work to other other technicians based on the piano make, condition and required work, and material preferences or other specific needs of the client. I find it quite refreshing! It makes me trust a technician even more!
.

I’ve spent a lifetime in an industry with highly trained and educated professionals... and the truly great ones never demeaned anyone else. Just sayin’


+1

So did I!

Glad that Mr. Chernobyl wasn’t in our team (to much negative radiation 😉)!
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/09/20 11:44 PM
Originally Posted by P W Grey
I was thinking of adding weight to the back of the tenor bridge, and/or possibly a riblet strategically located to reduce the amplitude of the low tenor notes, thereby easing the transition to the bass. I like starting there because it's a lot easier to do and is also quickly reversible if ineffective. Sometimes a similar treatment can be done at the bass bridge too. A quick experiment is to use mini vise grips on a bridge pin to see if any improvement. I would also consider adding weight to the bass hammers (mini binder clip on shank experiment) since the physical weight of bass hammers is significantly less than the tenor hammers right there. All of which is much easier than shimming the bass bridge for DB.

Just my .02

Pwg


Thanks for the thoughts and suggestions. smile

Well... mess with the low tenor, which sounds fine, so it matches better with the upper bass which really isn't bad, just could use some improvement? Btw Arledge rescaled and provided the wound strings. He only changed the lowest tenor note to wound, so I take it as a sign that the tenor is pretty good.

The "not great" sound of the upper bass is noticeable to me without comparing to anything else, and since it is the only place with less than desired DB, everything points to me to shim the bridge. I have had good success doing so just above the treble break and have to admit I am looking forward to seeing what it might do to the upper bass. You can call it an experiment. Since I will be using hide glue, it is also reversible.
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/10/20 02:39 AM
Looking forward to success when the deed is done. 😊

Pwg
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/10/20 03:39 AM
Originally Posted by UnrightTooner
Originally Posted by P W Grey
I was thinking of adding weight to the back of the tenor bridge, and/or possibly a riblet strategically located to reduce the amplitude of the low tenor notes, thereby easing the transition to the bass. I like starting there because it's a lot easier to do and is also quickly reversible if ineffective. Sometimes a similar treatment can be done at the bass bridge too. A quick experiment is to use mini vise grips on a bridge pin to see if any improvement. I would also consider adding weight to the bass hammers (mini binder clip on shank experiment) since the physical weight of bass hammers is significantly less than the tenor hammers right there. All of which is much easier than shimming the bass bridge for DB.

Just my .02

Pwg


Thanks for the thoughts and suggestions. smile

Well... mess with the low tenor, which sounds fine, so it matches better with the upper bass which really isn't bad, just could use some improvement? Btw Arledge rescaled and provided the wound strings. He only changed the lowest tenor note to wound, so I take it as a sign that the tenor is pretty good.

The "not great" sound of the upper bass is noticeable to me without comparing to anything else, and since it is the only place with less than desired DB, everything points to me to shim the bridge. I have had good success doing so just above the treble break and have to admit I am looking forward to seeing what it might do to the upper bass. You can call it an experiment. Since I will be using hide glue, it is also reversible.


Curious:
Is that bass bridge that you may shim cantilevered?
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/10/20 02:32 PM
Yes, cantilevered. Pretty rare to find a piano that isn't. I know what Del says about them.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/10/20 02:50 PM
The
Originally Posted by UnrightTooner
Yes, cantilevered. Pretty rare to find a piano that isn't. I know what Del says about them.

They are abundant sorry to say and I use Del’s mod fix every time I can.
If there is a rib near the upper bass bridge for support consider a wedge or spring to help prop it up a little?
Easily reversible and a mm or less could make a difference.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/10/20 04:10 PM
I thought of that and may try just to see. I am concerned that it might not be appropriate for two reasons. First, the cantilever is short there and so would take more force to have an effect. Second, it would transfer the sound to a part of the board that is less lively, which is why there is the cantilever in the first place.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/10/20 04:34 PM
Originally Posted by UnrightTooner
I thought of that and may try just to see. I am concerned that it might not be appropriate for two reasons. First, the cantilever is short there and so would take more force to have an effect. Second, it would transfer the sound to a part of the board that is less lively, which is why there is the cantilever in the first place.


As an aside: I have used small spring under bridge on rib in the killer octave area where there is considerably more potential string bearing because of the density of unisons as opposed to bass.
It does not take much to get a perceptible improvement - (it don’t always work very well)
There is no increase measurable in bearing but I don’t think that matters. It just adds some much needed responsiveness to the board.
The very small area of contact of spring on board in bass likely will not transfer much sound where you don’t want it.
The attempt to use cantilever to take advantage of a more lively part of the board is a grand idea that is doomed to fail imho add to that the presumed added benefit is longer strings that gives the impression of better sound also is self defeating because it demands a very short backscale that limits bridge mobility. (Del’s ideas restated)
Another aside:
I have modified based on Del’s ideas these things several times and done rescaling only to find that slightly shorter bass strings with a longer backscale sounds great. Longer is not necessarily better.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/10/20 04:52 PM
One other spring thought since your concerned about maintaining cantilever integrity:
If there is a support beam and rib near the upper bass bridge, use a spring to wedge up the bridge where the cantilever is glued and mounted to the board, slightly add some spring response to the entire bridge assembly.
Posted By: Gene Nelson Re: "Oilcanning" Soundboard Skeptic - 02/11/20 07:03 PM
For what it’s worth: here’s fun a wasted effort story to laugh at:
One other thing I tried but it was so difficult I ruled it out for future efforts.
I purchased some very powerful industrial rare earth magnets that have strength ratings.
A rectangle about 1-1/2” x 1” by 1/4 in thick was rated to attract or oppose 35 pounds if memory serves.
They come with predrilled countersunk screw holes.
One under bridge on rib and one opposite on support beam set to oppose I thought would add mass as well as lift and responsiveness and possibly a little bearing.
Interesting idea but mounting them in a rigid position was just about impossible.
If I had the right tool and coordination and mounting device it may have worked, someone with more skill than me may be able to do it.
Posted By: UnrightTooner Re: "Oilcanning" Soundboard Skeptic - 02/11/20 10:38 PM
So regain crown at any cost? I dunno. Do we really know what effect crown itself has on tone? There is little doubt in my mind that DB is important, but crown? Like, imagine a perfectly crowned board (whatever that might mean) but not enough DB. Would you then try to make the board crown more?
Posted By: P W Grey Re: "Oilcanning" Soundboard Skeptic - 02/12/20 02:57 AM
I believe that crown was introduced (way back when) to:

1) Add stiffness tobthe structure without adding more mass (weight)

2) To control (to some degree) what would happen to the panel when subjected to humidity changes

3) To act as a sort of "expansion joint" control mechanism

4) To create tension in the structure and (hopefully) help it vibrate

Spruce and pine and hot hide glue was what they had to work with. If they had carbon fiber and epoxy back then they probably would have used it.

Pwg
Peter,

You got it.

However I would disagree with point 4. Compression makes the board have more density. Before the compression method was discovered, soundboards were made with the grain going in the opposite direction. They were based on the tension principle ( like the tuning fork epoxied to spruce demo) from Ruckers to Broadwood. One reason for the switch , i believe, from a tension board to a compression board is because wood is 25% stronger in compression.

Also, I am fortunate to hear the difference of when a board has no compression to when compression develops. The difference is amazing.

-chris
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