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I agree with BDB.

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Instead of people making a point to publicly agree with other people, I hope people will start taking the time to give their own opinions.

Granted, BDB does bring up prior points that what you are considering is not likely to improve the sound, but the other issue--that I don't think had been mentioned yet--is that it is also not likely to increase the value of the instrument either. That's a significant point that deserves some consideration.

Originally Posted by A-Piano
1) Is there a way to use epoxy/ CA/ something to stabilize and pretty-up by bridges without making it impossible to pull the pins and recap them in the future?
Your bridge cap needs to be replaced. Anything that you do to the cap now, won't change the fact that it will still need to be replaced later. Nothing that you do with CA/epoxy will interfere with that process in the future. Do whatever makes you feel comfortable. Again, I don't think anything is necessary, and I know that sounds strange, but that is based on my own experiences. I could explain more if you want to walk thorough that.

Originally Posted by A-Piano
2) Thoughts on a thin coat of epoxy on top of the bridge instead of graphite and burnishing?
Well, if you put the epoxy in the hole, it is going to spill out and onto the graphite. So, that is why people using that method just end up covering everything. I wouldn't necessarily re-graphite and burnish, unless you are going to clean up the lines with the chisel, and that causes other issues. If you re graphite, you would have to have a plan for making it look good, otherwise just go for where the strings touch the bridge.

Originally Posted by A-Piano
3) Can I safely pull the plate with the pinblock and strings still installed (but tension let down of course)?
Yes. It is a normal benefit of that design. It is the whole reason what that exists. I don't know when Baldwin started doing that, or if they have always done that, but if you take a picture of where the pinblock touches the action cavity, we can tell you.

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3) Can I safely pull the plate with the pinblock and strings still installed (but tension let down of course)?


The answer to this question is: Maybe...it depends on whether or not they put in a hidden screw or 2 or 3... Nothing is etched in stone in this department.

But if you are going to replace the PB why would you want to do that? And if you are not going to replace the pinblock what's the point of removing the plate? Then again maybe I'm missing something (wouldnt be the first time).

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Last edited by P W Grey; 01/04/21 01:31 PM.

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Originally Posted by A-Piano
4) Is the 'rear' bridge pin also supposed to be 90 degrees relative to the non-speaking section of string between the bridge and the hitch pin? Similarly, is there a standard for the amount of 'side' tilt of the bridge pins (into the edge of the string?) Or is that the 6-7 deg?
The 90 degrees means the speaking lengths should be the same length. The position of the three front pins should be straight across (90 degrees, in the same plane, compared to the speaking length). This is the standard. The same thing applies to the rear pins. They should be straight across. Does it matter? Well....

Fun fact, Bösendorfer and some other Viennese piano makers used to do it in a different way. There was an approximate 2mm offset between each of the three pins. So, that produced three separate string lengths of significance. Based on the modern standard of the straight across (90 degree line), this should be horrible. Guess what? It was fine. It worked. There was a difference, but I would characterize it as more interesting. It wasn't a good or bad kind of thing.

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Originally Posted by A-Piano
when you say there is a lot of side-bearing, do you mean this piano was built with more side-bearing than typical, or just that things look good based on how much side bearing is (still) there. More curious than anything.
It is normal. You only have to worry about lose pins if there is no side-bearing to hold the string in place. There is more than enough there to get the job done.

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To clarify my previous post when i referred to the 90 degree angle. The fore and aft are angles so that the bridge pin is perpendicular to the string coming and going. The opposing side to side angles are the clamps.

Downbearing and Crown are two different things. Crown is referring to the boards condition. Downbearing is how much load the strings are applying onto the board.

A simple downbearing plan is to start at the tenor, leave board unloaded, and set the angle of that string under tension to .5 degree. Go to next note and do the same. Do that note for note. By the time you get to the center, the board is already holding its own. Work up to note 88, .5 degree all the way up. Then go to the bass bridge, which by this time will be in its final position. Set every note to half a degree. If you prefer, you can set the Uni's to zero. This downbearing plan brings out the most resonance of an old board or new one. It applies about 500lbs of downbearing pressure, which is plenty. After hearing the difference, i believe Wolfenden gave bad advice in his piano construction book of 1.5 degrees (The 1/40th rule). I just recently restored a Baldwin SD-6 that had 3 degrees of bearing. When i removed the strings, the board crowned back up, and when restrung to the plan above sounded like a new piano again.

Good Luck on your project.

-chris


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Originally Posted by A-Piano
I’d love to try the string tension trick you mention – since most of my ‘dullness’ is on the bass end, would it make a difference to do that just on the bass bridge, or would it not really be effective unless I did it across the whole piano?
OK, so, bass strings do have a limited lifespan. This happens with all wound strings. Particles get between the windings and dull the sound over time. Some people swear they have a method of rejuvenating them. Maybe, but after 20 years or so, pianos benefit from new bass strings. They just loose their cutting bite, and edge.

Originally Posted by A-Piano
I have ‘turned’ 3-4 bass strings (flipped the hitch pin over 180 deg) one-at-at-time per the suggestion of a tech a while ago. It made a LITTLE difference, but not a lot.
I never add twist to the bass strings like that. It can solve one issue, but it will cause other issues. The solution here it so install new bass strings.

Originally Posted by A-Piano
Any idea what causes that phenomenon?
Are we talking about the improvement in sound by resetting the system (lowing the tension and bringing it back to tension)? [/quote]Yeah. Many technicians only do small tuning movement the entire life of the piano. Doing so doesn't adjust the coil tension and the string segments behind the bridge. When you reset, everything has a chance to go to where it needs to be. With small tuning movements, the bridge pins have the wire lock into place, so you are making changes to only parts of the string. When you reset, everything is moving and nor locked down.

Originally Posted by A-Piano
I don’t want you to feel like I’m ignoring your advice here. I absolutely appreciate everything you, and everyone else, are contributing. To the contrary, I was convinced that I needed to recap when I started researching a few months ago and you, as well as others, have definitely brought me around to the idea of not doing a recap.
I totally get it. The recapping seems like the "logical" approach. Everything else seems like a shortcut. Doing nothing sounds even stranger. My experience with this stuff baffles even my mind. It has been a lot of trial and error. I've seen and done many crazy things to the soundboard, I and know that is not a sensitive as most people think. It is supposed to be the "soul" of the instrument. That is a bit overly dramatic. Even soundboard with no crown, or reverse crown will work just fine. Again, it all defies "logic." But, in the end, it is what it is. We test, we observe, and we draw conclusion based on those finding. What other people say doesn't really matter. Like that 90 degree, all strings of the unison the same length, deal. 99.9999999% of all technicians will say it has to be like that. But, no, it doesn't. I've experienced where the strings were purposefully and dramatically different lengths. Everyone is going to tell you, that's impossible, it's never going to work. But, it works. It sounds nuts, but it works.

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Chris, I think you inadvertently left out a key starting point - the newly strung piano does not yet have a defined position of the string on the vertical hitch pin. All the strings are set to zero degrees bearing so that the board is not yet loaded by any of the strings. From there, you would proceed as you have described.


For those of you who rebuild and find this process interesting, you can cut your teeth by installing vertical hitch pins in the bass to replace the original hitch pins. You knock off the old pins with a cold chisel and grind down the surface to be smooth. The new hitch pins are installed behind the old ones (when there is sufficient space on the plate to safely do so, which is not always the case.

For grands under six feet, this will increase the back scale length a meaningful amount, most especially in the monochords. There is tonal benefit, as the longer back scale is free to make larger excursions. And you can set downbearing individually for each string.


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A-Piano, consider restringing with Paullelo wire. This is no more difficult than using ordinary wire, and Paullelo provides a spread sheet to calculate the scale.
http://www.stephenpaulello.com/en/cordes
Heller and J. D. Grandt can calculate and make bass strings using Paullelo wire.
Hans Velo's site has demos of bass rescaling.
http://home.kpn.nl/velo68/

You say the bass is dull. I hope this is due to dead strings, but do check carefully for bridge problems.

Bill Spurlock's 1990s PTJournal articles on bridge resurfacing for restringing are the classic source.
In my last shop work I decided against filing or sanding the bridge pin tops which can loosen the fit of the pins. I preferred drilling and gauging to insert pins to an even depth.
The late Ron Nossaman warmed the bridge before applying epoxy and showed samples of sliced bridges to show that the heat thinned the epoxy and drew it further into the bridge.

If you can get a reasonably good belly on this piano, it should be capable of serving as a good home piano. It won't project to fill a big auditorium, but could be a piano you can modify to give sensitive touch and beautiful voicing in the quieter dynamic range.

Has Mario Igrec's _Pianos Inside Out_ been mentioned? This book is full of information for your project, especially about action geometry, and is the best overall text available. (He's not quite up-to-date on Paullelo, and the Pure Sound wire he mentions in passing is defunct for good reason, it did not hold up over time.)


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I am going to submit that the only reasonable approach to repairing the bridges is recapping with new wood and drilling, notching, etc. I will ask all of you who posted opinions on the several courses of action for repair to revisit the pictures of the bridges that A-piano provided us with. The format allows us to blow up the pictures in size where we can look closely at the compromised notes, so please do so.

When I did this it became quite clear just how bad the bridges are. I see places where the bridges are not only splitting at the pins, but have multiple splits nearby. I see pins where the split is so great that the pin has migrated as the wood gives way and there is a large gap on the side. The pins have moved, and will not allow us to make a reliable pattern that we can work from to locate new pins. That means that the only good solution is the string method already described, along with a plexi 6 pin pattern for the trichords to avoid introducing the failings of the compromised cap. These failings and others are too widespread to avoid making the decision to replace.

This also means that the condition of the notches is such that making a sufficiently accurate pattern to use with epoxy and new pins, or to plane down the bridge top to rid the string impressions and then renotch is a very poor choice. I don't think the maple used on this bridge was of particularly high quality and it is giving up the ghost.

Anyone who has suggested that we can go with the bridges as they are and then go to the trouble and expense of replacing the pinblock and restringing is talking out of their hat and should not be giving advice.


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Originally Posted by WilliamTruitt
Anyone who has suggested that we can go with the bridges as they are and then go to the trouble and expense of replacing the pinblock and restringing is talking out of their hat and should not be giving advice.
Why has it been suggested that the pinblock needs to be replaced? Is it cracked and destroyed? If there is nothing wrong with it, and it still has the original pins in there, then there are still many life cycles of pins to go through before the pinblock gets replaced. Pin blocks last a long time, and the reason we have something like 18 sizes (increments) of pins is to get the maximum life out of the pinblock. Pinblocks are designed for the pins to be replaced many times before there is any thought of replacing the block itself.

Originally Posted by WilliamTruitt
I am going to submit that the only reasonable approach to repairing the bridges is recapping with new wood and drilling, notching, etc. I will ask all of you who posted opinions on the several courses of action for repair to revisit the pictures of the bridges that A-piano provided us with.
I'll restate that the professional approach is to recap the bridge and to use the strings (or the line) to determine where to pin and notch the piano. Making a reliable pattern isn't reasonable for a number of reasons, some of which WilliamTruitt stated, but there are others. So, having someone else make a new bridge for OP, really isn't a good solution. It may look good in terms of workmanship, but it won't be right for that piano. Epoxy/CA is just something that makes people feel better about the situation so that they can say they tried.

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The great part of OP situation with the design of his piano is that he can restring the piano with new tuning pins. He can do that first, without doing anything to the bridge. As bad as they look, there isn't going to be any notable or significant impact on the sound. That just is how it is. OP can confidently restring the piano first. If he still wants to redo the bridge later, he can do that without having to remove the new strings. That is the advantage of that design, compared to something like a Steinway, where that is not possible.

If OP really wants to experience what changes in the piano effects what parts of the sound. I would restring first anyway. This way you know the sound of the piano with new strings. When you change cap, you'll know exactly if and how the sound changes. Again, a new cap is the professional thing to do, but the difference in sound will be negligible.

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Another approach to bridge repair is to drill out a small damaged section and fill it with a plug of similar wood.

Yet another would be to install Phoenix bridge agraffes in the bass and tenor, bypassing concerns about down bearing!


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Ed, you drank ALL the koolaid, didn't you! Good for you. :-)


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"Why has it been suggested that the pinblock needs to be replaced? Is it cracked and destroyed? If there is nothing wrong with it, and it still has the original pins in there, then there are still many life cycles of pins to go through before the pinblock gets replaced. Pin blocks last a long time, and the reason we have something like 18 sizes (increments) of pins is to get the maximum life out of the pinblock. Pinblocks are designed for the pins to be replaced many times before there is any thought of replacing the block itself." This is unadulterated trolling, not worthy of further comment.

"As bad as they look, there isn't going to be any notable or significant impact on the sound." Whether it is from ignorance or malice, it is shameful for you to mislead A-Piano and perhaps others in this way. There definitely are tonal consequences to this degree of deterioration, and if you can't hear them, you must be an oaf. And you say you have trained dozens of apprentices to do bridge work? OK.

Maybe you are just disoriented. The OP's piano is 90 years old. It is likely that there are several screws at each end that anchor the pinblock to the rim. They are under the plate, likely 3 or 4 of them at the treble end and 1 or 2 at the bass end. You have to remove the plate to get at them, which means you have to de-string the piano.
The modern Baldwin system did not exist back then.


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The advice that one should give depends on the circumstances. Restoring a piano of little value for learning purposes is not the same as restoring a valuable piano for profit or resale. Someone making a living at doing restorations has a better chance of everything going well than an amateur doing it for the first time. Making a mistake on a small job is easier to correct than several mistakes on a large job.


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Originally Posted by WilliamTruitt
Maybe you are just disoriented. The OP's piano is 90 years old. It is likely that there are several screws at each end that anchor the pinblock to the rim. They are under the plate, likely 3 or 4 of them at the treble end and 1 or 2 at the bass end. You have to remove the plate to get at them, which means you have to de-string the piano.
I don't think it is disorientation. I believe I said a few different times in a few different ways, I don't know when they made the transition to the modern design. I don't have the information to say one way or another. You could be right. I don't claim to know one way or the other on whether or not there would be hidden screws in a 90 year old Baldwin.

I know what I don't know, that's for sure.

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In my years editing the Piano Technicians Journal I had to learn that there are many situations and many ways to do good piano work, even by people whose approach I didn't like.
In the situation he has described, A-Piano can choose from a wide range of methods, and probably any of them would produce worthwhile improvement, and enjoyment in doing the work.


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Originally Posted by Ed Sutton
Yet another would be to install Phoenix bridge agraffes in the bass and tenor, bypassing concerns about down bearing!
Where do you buy the bridge agraffes?

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