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Hi all, as you can see from the subject line I'm after a bit of advice on hammers. I'm coming to the end of a lengthy first grand piano restoration that has seen me refinishing the soundboard, making new bridges, repainting the frame, making a new pinblock and lastly restringing.

Some time ago I had a new set of hammers made by Abel in Germany, these were hung on new shanks and they were fitted for a time before I destrung the piano and commenced the restoration. From the outset they were a problem. The old hammers were only very lightly worn but needed recentering and i figured that new felt would improve the tone. I think this was not a wise move. Despite asking them to use a light pressing the felt on the new hammers is very much harder than the old and the resulting sound is a bit too robust for the piano. Basically it used to be quite mellow - perhaps too much so, now it is much to bright and too loud really. The other major issue is the weighting of the action has been completely upset; I've fitted new whippens with the auxilliary springs but they add too much compensation. I realise that I could adjust the weights in the keys etc, but it is the sound that I'm most worried about at this stage.

After restringing I've tuned it several times and it is now holding tune well. I popped a whole section of the old hammers back on as an experiment and after the roughest of regulation I have to admit it feels much better to play, key weight is good, it's controllable and sounds nice and mellow.

The thing is, I just don't know what to do with the hammers; do I fit the old ones and store the new set to one side - thus potentially getting no value from the £950 investment I made in buying them, or will it be possible to voice in the new ones to calm them down a little (I'd get a tech in to do this)?

I suspect that whilst voicing would calm the new ones down a little it won't be possible to do enough without wrecking them and voicing isnt going to solve all of the weight issues. I'd guess that a brief pass of the iron over the tips of the old hammers would bring a touch more sparkle and that's going to be the best solution.

Any advice appreciated!

I take it that you are not a technician, as you mention calling one in.

Changing hammers is a bit more involved than taking the new ones off and putting new ones in. (You Brits love your understatements, so there you have one)

You can't simply exchange hammers and wippens and expect everything to work out - there is a whole lot more to it, a greater understanding of action geometry, mass and inertia of moving parts etc.

If you like the way the old hammers work for you, then maybe you are best off using them. If you want to use new parts, you would be best advised to seek out the help of a qualified technician who is experienced in the items I outlined.

There are several problems here. First you did not match the mass (weight) of the new hammers to the mass of the originals. The new hammers are considerably more massive than the originals, hence the very high action weight. You have tried to compensate for the extra mass of the hammers by using wippen assist springs but that is somewhat like using a strip of tape and some gauze to treat a broken arm. And, yes, you could adjust the weight of the keys but that will increase the inertia of the whole system and you probably won’t like the feel of that either. You really need to find some hammers that have approximately the same mass as the originals.

Second, the new hammers are much denser (harder) than were the originals. You don’t tell us what kind—or size—of piano you have so it is not possible to give specific recommendations about what hammers might be appropriate for your piano but we do know that the hammers you now have are both too heavy and to dense. (And both of these characteristics will affect how they sound on your piano.)

It would be nice if you could start over and order hammers that are more appropriate to your piano but it sounds like it might be too late for that. Still, all may not yet be lost. Without knowing just how much extra mass you have on these new hammers It is hard to tell if you can make them work on your piano or not but there are a couple of things you might try. Sometimes you can remove enough extra mass from hammers to make them work. You can trim the sides of the hammers quite a lot. You can more aggressively shape the lower part of the hammer. Depending on how much extra mass your hammers have these steps might help.

Excessively bright hammers can be voiced down considerably. They won’t end up sounding quite as good as hammers that were pressed to the right consistency in the first place but they can probably be improved quite a bit. This is skilled work, however. If you’ve gotten this far into your rebuilding project without major mishap it is something you could probably learn but I’d strongly recommend hiring a qualified technician to work with you. It’s pretty easy to ruin a set of hammers if you don’t know what you are doing.

ddf

Thanks for the replies. Yeah, I'm not a qualified tech, I've just been using Reblitz as my guiding light!

I've been happy to work on all other aspects of the restoration - such as the restringing and bridge work and I'm happy to say thats turned out very nicely. I've rebushed the keys, levelled and squared them and basically tackled everything I can do more than once should I go wrong the first time over. However, I don't think hammer voicing is something I should attempt because as you point out, I could wreck them.

The piano in question is a 1936 baby grand at just over 5' long. It's a British make: "Rogers" which was reasonably respectable in its time.

When I ordered the new hammers I sent the top and bottom hammer from each section to Abel in Germany and they replicated them as best they could. It appears that they can no longer do a felt pressing that has the same density as the originals. When I got the hammers back originally (before I started the restoration) I had a tech visit for a day and he fitted the hammers, matched them to the strings and did a little regulation. What he didnt do is any voicing. I found these hammers really revealed any weaknesses in the old strings - false notes were now really noticable as everything was so much brighter and more revealed. This is what caused me to undertake a restring.

It may be possible for a tech to remove some of the material from the side of the hammers, but I think Abel replicated the originals quite well in terms of size (they are narrower than standard) and I'd say they were like for like with the old ones in terms of width. I notice that they tapered the tails a little over standard too so I suspect they've done all they can to reduce the mass.

Thanks folks.

James

It sounds like this has been a real learning experience for you. Congratulations! But the learning is not quite over yet. The clue to your current problem is found in the above sentence, “Abel replicated the originals quite well in terms of size….” Yet, were you to weigh samples throughout the set and compare their weights to the original hammers from the same notes in the scale you would find that the weight of the new hammers is considerably higher than that of the originals. The only way to make hammers of the same physical size heavier is to make the felt denser; i.e., make the hammer harder. And that is what has happened here; your new hammers are both too heavy and dense for your piano’s action and its scaling.

Older pianos of this type tended to use relatively light (by today’s standards) hammers with relatively low-density felt. Commonly available modern hammers are generally not like this at all. I don’t know if there are hammer makers in Europe that can come close to replicating the characteristics of your original hammers or not. In the U.S. many of us rely on the skills of Ray Negron at Ronsen who still presses hammer in much the same way as did those early hammermakers.

In your search for more appropriate hammers remember that matching the weight is just as important as matching the physical size of the originals.

ddf

I got into a situation a lot like this one here. Years ago I had sent off a set of sample hammers for duplication from a Starr Baby Grand.

The hammers I got back made the action very heavy, and quite tiring to play. Plus it just didn't have the tone that I had hoped it would.

I worked with the action to regulate it, took all the mass I could off the hammers, hunted friction problems and just could not get where I wanted to be.

Thanks to the forums here along with the information Del gave me I was able to have a set of hammers built by Ray at Ronson Hammers and the difference has been well worth the trouble.

Ray Negron called and visited with me twice to make sure what we were doing was right, and found some specs for the original hammers that should have been on the piano to start with.

Not sure where he found that info, but the transformation has been amazing. Even though the Starr may not have been the best piano in the world even when new, it certainly has a very pleasing sound now and the action is much lighter than it was. Even right out of the box with no voicing and little regulating work the piano was vastly better.

Having the right hammers certainly makes the job easier. But the rest of the piano has to be right too.

Many thanks for the advice folks, you've pretty much confirmed what I'd thought about the new hammers. I don't believe there is anyone in Europe who can do light pressings like the originals any more. Since they've only had light wear I'm going to re-centre the originals and pop them back on I think.

Thanks.

James

Del,

thank you once again for sharing your pro insight into this matter!

I would have thought that sending the samples should be enough to get the appropriate hammers!

If I understand well, the samples were not weighted by Abel?

They only replicated the sample's dimensions!

The density and the hardeness are not checked by the manufacturer of the hammers?

Is this a choice made by the buyer?

I have a great deal of trouble believing that the old piano manufacturers specified the weight of the hammers. So few of the things that could be specified seem to make any logical sense, so why would they suddenly decide to be so exact with this one particular?

One thing I am sure of is that the light touch on a lot of older pianos is not original. Things dry out and lose weight. Springs fatigue, and have less resistance, even if they work almost as if they were new. This gives a sensation of lightness which is not the way the piano was originally.

I doubt that they did weigh them. Or that they specified the weight. It’s just how they made their hammers. The felt was generally less dense and the hammers were not pressed as hard.

Nor do I think they suddenly decided to be so exact with this. I think this requirement evolved over time—as did so many other things—as the needs of consistent production became ever more important. If you are going to pre-lead a keyset and expect it to work within some consistent touchweight parameters hammer mass has to be controlled.



I’m not so sure of this. What dries out? Wood is seasoned to some fairly low equilibrium moisture content before the keys and actions are machined. This is not a new process; woodworkers have been doing this since forever. Wood does cycle through the year as the seasons change but, other than this, how is it going to change weight over time? According the Wood Handbook it doesn’t.

Nor can I see how felt is going to “dry out” and change weight over time. Obviously if the hammers have been sanded a few times they will be some lighter than they were originally but not all old hammers have been sanded. I’ve weighed enough hammers from old pianos to convince me that the dominant factor in this was hammer mass.

Take a look at the overall action ratios from the period. It’s not all that unusual to find them up around 5.7 to 6.0. Well into the mid-1900s pianos were being built with action specifications of 1.75” (≈45 mm) hammer blow and 3/8” (≈9.5 mm) keydip. That still requires an OAR of around 5.6 and you’re not going to make that work with a heavy hammer. Even though some of those hammers were physically quite large they didn’t weigh all that much. They couldn’t have if piano makers were using these OARs and the actions were working.

What’s left to lose weight?

ddf

I've heard a number of techs express this idea, and have always wondered about it. A properly designed spring really won't fatigue to any meaningful degree. Have piano manufacturers been using a poor alloy, or a good alloy poorly tempered, or a good alloy, well tempered (no pun intended), but exercised too close to its elastic limit? Good springs are often made from spring steel, beryllium copper, or phosphor bronze.

Even if the DO lose their strength, in a grand that would lead to loss of repetition, not lighter touch weight.

Jurgen: As I said, it leads to a lighter sensation, even on grands. Eventually the spring gets compressed, and you feel it. There is a marked difference between new springs and old.

Roy: The chances of anything being designed properly in a piano are pretty slim, especially when it involves using a more expensive material. But springs wear out all the time, and not just on pianos. That keeps shock absorber manufacturers in business.

Del: I am not certain where the weight changes. One could take samples of the felt and wood from old pianos and compare them, but I do not have scales which are sensitive enough. But so far, it is a mystery.

I am confused about the whole idea of how much the action ratios have changed. The specifications for key dip are rather vague, as manufacturers seem to measure them at different point on the key, and often do not specify where they are measured. Tolerances are rarely given.

We have also seen a change in measuring the weight itself. Formerly it was measured in ounces, which gives rather crude tolerances compared to grams.

Yes, key dip specifications by themselves are rather vague. That’s why action ratios are not measured that way. There are two basic methods that I use. For a quick check I have a simple tool that depresses the key 6 mm at the front rail pin (actually, 20 mm back from the front of the key). I measure the actual distance the hammer travels as a result of that amount of key travel. I divide the hammer travel by 6 and I have a measure of the overall action ratio.

The other is to measure the various lever arms and work it out mathematically. Both methods, done carefully, are reasonably accurate.

I’ve measured enough old and new actions to know that action ratios have changed significantly over the years.



I’m not sure what this has to do with the actual weight of either the old hammers or the old action parts. The question is whether or not wood and felt change weight over time. I don’t like theories based on vague mystery so, until I learn of some mechanism internal to either wood or felt that can cause this change, I will continue to believe that they do not. That is certainly the way all the evidence known today points.

ddf

I don't understand this statement. Shock absorber manufacturers don't make springs.

What gets replaced in cars, washing machines, etc. is not the spring, but the shock absorbers. Those are two very different things. The spring provides a restorative force, while the shock absorber damps (or resists) movement.

In my family, we have a 28 year old car, a 21 year old car, and a 19 year old car. All three have had numerous exchanges of shock absorbers, but all three are still running on their original springs.

Under normal loads and stretching/compression (i.e. within their elasticity and design limits), springs hardly ever wear out. Should it really be so different in pianos? This would mean that piano designers are putting under-rated springs into pianos, and that the springs become over-stretched and fatigue during normal playing.

I'm not trying to put BDB down - just trying to understand why springs in pianos should fatigue while they last for decades in cars, washing machines, etc.

Yes, I was going to say the same things, but you beat me to it. If car springs fatigued over time, you'd see cars drooping closer and closer to the ground over time, and that doesn't happen.

If springs fatigue in pianos, I bet it's due to poorly thought out designs, and if the designs were appropriately modified, springs that would last forever could be designed that would cost no more than the poorly designed ones.

Well, I have seen plenty of old pianos where the hammer return springs and jack springs and damper springs didn't have much spring left.

So where have the action ratios changed? Was this deliberate or designed?

I apologized. I should have said that measuring touchweight in ounces implies a wider tolerance than measuring it in grams. (2 oz. is about 55 grams, which is probably where the standard came from.) It may be that old pianos were designed with 2 oz. touchweight, which is what they got in the factory, and that they got lighter as the actions got looser, of course.

The question of the weight or density of materials is separate. I still have a difficult time seeing where the change in that came from.

Well, rather than arguing that what obviously does happen cannot happen, by all means go ahead and design springs that will last forever. I would love to have a grand piano with repetition springs that never need adjusting, or piano strings that never wear out.

I bet in all the cases cited of springs that "last forever," the demands put on the springs are so gross that you do not notice that they have changed.

What about a spring could cause it to lose its “springiness” over time?

I agree with BDB (and others) who have encountered action springs that have probably lost some amount of tension over some decades of time. I say “probably” because we don’t really know what the strength of these springs was originally; we only know that they are too weak to do their jobs properly today. It seems a stretch to attribute all of this this to poor initial action design when the builders of these actions got most everything else right. And when we encounter other pianos using the same action that do not exhibit this phenomena.

These show up in uprights in both the hammer butt springs and, less often I think, in jack springs. It is possible the manufacturer deliberately used very weak springs, of course, but it doesn’t seem likely. In the upright weak action springs results in a relatively light key touch weight and action repetition can be rather unreliable even when the action is otherwise well regulated.

It shows up in grands in the wippen repetition spring, not always and not even frequently, but often enough. I disagree that this affects touch weight (in a grand) but it certainly can affect repetition. Reliable repetition can be a problem if the repetition springs cannot be adjusted properly.

Piano action springs have been made of a variety of materials ranging including brass, “phosphor bronze” and various grades of steel.

ddf

I did not say that repetition springs affect the touchweight. They do affect the feel of the action, however, which is what I said.

Steinway repetition springs seem to have a lifetime of about 65-70 years.

I have encountered actions 80 years old, all original parts where the springs are clearly too strong and have to be eased.

I wonder what the spring tension difference really is by the time we notice "too weak", "OK" or "too strong".

Of course, there are all the "previous adjustments" that we were not there to see how they were set.

There seem to be so many variables that have nothing to do with the quality of the spring itself.

When I was buying shock absorbers for a vehicle, I called and talked to the tech department about which would be best for my application. They suggested that if the vehicle had 50,000 or more miles on it that I replace the springs.

New springs made the ride height 2"/50mm higher. The shocks were the type that are dampers only, they were not gas charged to alter the ride height.

The wippen spring does effect the touch at the bottom of the keystroke. You can really feel it when you adjust them from strong to weaker - it's noticeably easier to play to the bottom of the key on a slow blow.

Spring tension loss could be a result of increased friction at the pivot points.

Not really. The spring tension isn’t changing it just has to work against action centers with more friction.

ddf

I agree with all of this; yet there are some occasions in which I’ve encountered springs that appeared “normal”—normal diameter, normal design, normal shape (no kinks or other signs of damage—but they are just washed out. It is not possible to “adjust” them to give what is thought of as normal function and action performance.

ddf

Yes, I agree, but it would give the tech the perception that the spring has gotten weaker - without doing a u/d evaluation.

I agree that this can affect how the action feels to the pianist. It does not, however, affect how the action measures when a touchweight analysis is done.

ddf

Spring tension does affect the touchweight of uprights very strongly, both hammer and jack springs. Damper springs affect uprights and grands, if they have them, although not the initial touchweight. Everything affects the player. In years past, I found myself over-pedalling when I played because it made the action easier to play. I have adjusted my technique and no longer pedal nearly as much.

Agreed ..

Could it be that these springs had already been "adjusted" numerous times in the past? I ask this because the only way to adjust a spring is to bend it past its elastic limit, and force it into plastic deformation. To my knowledge, this weakens the spring (although an initial improvement may be achieved) - especially if the spring is bent repeatedly.

Well, I don't know of any grade of brass that makes wonderful springs, and some grades of steel make better springs than others. Maybe we're seeing the result of material selections that resulted in springs that lasted a reasonably long time, but not long enough for the really old pianos that people regularly encounter. Also, the loss of springiness could be the result of the design--if one designs an action spring that lasts 20 years rather than 50, is that bad design or just a reasonable compromise if it made the spring cheaper to make and/or easier to adjust?

When I look at the very common butterfly type of wippen spring, it strikes me as a design that's likely to fatigue, but it's hard to say without doing some analysis.

What do you mean, “where have the action ratios changed?” Earlier in this thread I wrote:
“Take a look at the overall action ratios from the period. It’s not all that unusual to find them up around 5.7 to 6.0. Well into the mid-1900s pianos were being built with action specifications of 1.75” (≈45 mm) hammer blow and 3/8” (≈9.5 mm) keydip. That still required an OAR of around 5.6 and you’re not going to make that work with a heavy hammer. Even though some of those hammers were physically quite large they didn’t weigh all that much. They couldn’t have if piano makers were using these OARs and the actions were working.”

The overall action ratios in modern pianos can be down around 5.2 to 5.4. That’s quite a difference and the need for the change is entirely due to the increased mass of the hammers being used today.

This change has been quite deliberate. The OARs can be easily changed (in production) by relocating the key balance point and/or by relocating the capstan and/or the knuckle.



Well, density, perhaps, but I don’t see how hammer weight and action ratios can be regarded as separate issues; they pretty much have to be considered together. In the misguided quest for evermore power hammers have been getting more massive. Changes in hammer mass require balancing changes in action ratios. Human fingers, hands, wrists and arms can accommodate only so much physical stress and strain. Everything else being equal any increase hammer mass is multiplied by the OAR at the end of the key. In other words, if the hammer mass increases from, say, 8 grams to 10 grams and the OAR is 5.6 the key touchweight is going to go up by 2 x 5.6 = 11.2 grams. If the original key touchweight was 52 grams it is now going to be 63.2 grams. That’s quite a lot of extra strain on the pianist’s hands. To drive these heavier hammers the OARs going to have to be reduced and the keydip increased.

This example is not an uncommon one. Above I wrote that early 1900s hammers didn’t weigh all that much. To put numbers to this I have frequently found older pianos with the #1 hammer weighing around 7 to 8 grams. Today, the #1 hammer is likely to weigh closer to 10 or 11 grams; sometimes more. Who knows where it will end. I’ve recently learned that Steinway is going to be using 24# felt for their Model D hammers. (Note: For those not familiar with hammermaking practice that’s the weight of a sheet of felt from which approximately 14 sets of hammers are made. For comparison, in the 1970s a typical felt sheet would have weighed 16# or #17#.) I don’t yet know what the actual hammers made from this felt are going to weigh but it ought to be interesting seeing how the action geometry works out and how action saturation is handled.

Nor have treble hammers escaped the binge. Treble hammers in the early 1900s might have weighed 3.0 to 3.5 grams; nowadays they are more likely to weigh 4.0 and up. Sometimes, well up. I’ve found C-88 hammers on modern grands weighing upwards of 5.0 grams. So, it’s not just in the bass; across the compass of the action piano hammers have been getting heavier.

The problem described by the OPer is all too common. I’ve been asked to look at more than a few older actions with the complaint of excessively heavy touch weight only to find replacement hammers of some well-known brand that were simply too heavy for the action geometry in place. The best solution is to toss the inappropriate hammers and fit something closer to the originals in both mass and density. Unless this is done changes to the action will be required; the keys will have to re-leaded to compensate (usually a very unsatisfactory solution) or the geometry will have to be changed.

ddf

Whenever there is a change in something like the action ratio, I find myself wondering how much was design, how much was error creep, how much was fudging to get it to work, etc.

I was down looking for some old hammer shanks, sifting through my collection of odd hammers, and tried comparing an old (1912, I believe) bass hammer with a fairly new (1980s?) one left over from a set. Physically they were very similar, about the same molding and felt sizes, and so I taped them to either end of a piece of wire and balance them on a knife blade. They balanced quite close to the center, so they must be about the same weight.

I have noticed a lot more felt at the tip of hammer #88 and thereabouts. I cannot ascertain whether this is a change in manufacturing, or a change in hammer filing practices.

At any rate, the difference in hammer weights might be more from sales hype than anything else. Just as longer speaking length makes good advertising, heavier hammers also sounds more impressive. 16 lb. hammers sounds more impressive than 12 lb. hammers, even though the weight of the felt means nothing without considering how the felt is cut.

Well, there you have it; based on a test sample size of one we now know that old hammers are the same size and weight as new hammers.

I do wonder, though, what the results might be if the sample size had included hammers from, say, hundreds of old pianos of various sizes and these were compared to the hammers found on hundreds of new pianos of similar sizes or hundreds of sets of new aftermarket hammers being sold for use on old pianos of similar size. I also wonder what might be learned if more than one hammer per set were weighed on a precision scale of some sort—say every A hammer plus the top C hammer on a scale accurate to at least ±0.05 grams.



Actually, we do know a little more than nothing. It has long been industry practice to supply felt sheets such that the same number of strips can be cut from each sheet. It doesn’t tell us precisely how much each hammer or each set of hammers will weigh but the difference in weight between sheets does translate directly into a comparable difference in the weight of the hammers made from that sheet.
ddf

No, based on that sample, old and new hammers close to the same size weigh about the same. I could compare more, and I suspect that the results would be similar. However, hammers are not the same size whether they are old or new. Well, except if you go back to the pre-felt era.

Are you suggesting that cold-pressed hammers of the type commonly used some decades ago have the same density as modern hot-pressed hammers that are so common in many, if not most, contemporary pianos? Are you suggesting that key dip and action ratios have changed for no reason as opposed to for compensating for heavier, hot-pressed hammers? ...based on a sample of one? That sounds like a tough sell to me.

I am not suggesting anything. I explained what I did, and the results that I got. It may be a sample of one, but that is more than anyone else around here seems to have experimented with.

According to my teardown sheet, the A-1 hammer that I took off of the (1920s) Everett 5’ 3” grand I’ve written about in the past on this forum weighed 8.1 grams. It was ≈11.0 mm wide and measured ≈38 mm wide at the shoulder. The replacement—Ronsen with 12# Wurzen felt—measures ≈33 mm across the shoulder and weighs 8.5 grams. The Ronsen’s are some smaller but heavier.

By comparison, I have a set of Abel Natural Felt/Medium—not a particularly heavy hammer by modern standards—with an A-1 hammer that also measures ≈11.0 mm wide, is ≈35 mm across the shoulder and weighs ≈11.0 grams. By the time these hammers go on a piano I’ll get the weight down some by tapering their sides and removing as much excess wood from the moldings as possible but even so they would still be about 2.0 grams too heavy for the Everett piano and action. Unless I did something to compensate the touchweight would go up by about 11 to 12 grams. Physically, they would be smaller than the originals, though.

High-density felt can be pressed into relatively small cauls and low-density felt can be pressed into relatively large cauls. Looking at their physical size by itself doesn’t tell us much. We have to know their mass.

ddf

The principles I've provided in earlier posts is based on information gained from measuring and weighing thousands of individual hammers from hundreds of hammer sets over several decades of time.

ddf

This is the first time you have said that you actually weighed anything. I admit that my methodology is lacking, but at least I explain what it is. In fact, that is all I was doing, explaining a methodology and reporting the result of a test. You and Roy123 are the ones who misinterpreted what I was doing and leapt to a generalization.

I will do more testing later, but I have other things to do. I am particularly interested in comparing old and new Steinway hammers. In any case, there is no reason to accept someone else's conclusion when one has the means to test for oneself.

Right…

For many professional piano technicians weighing hammers is a standard part of every hammer replacement job. This is done so the technician can select hammers that match the weight of the original hammers and thereby avoid the problems raised by JamesP, the original poster.

The methodology is quite simple; as a first step in any hammer replacement job sample hammers are removed for evaluation. For consistency I remove every A hammer plus the end hammers of each section. Measure and record their width (just below the strike point), the spread across the shoulders, their overall length and (by placing them on an accurate digital scale) their weight. When selecting a new set of hammers for the piano the same hammers are weighed to make sure the replacement hammers will be of approximately the same weight.

After doing this for several decades with a wide variety of pianos that were built over a span of roughly one and a half centuries it becomes possible to begin forming at least few tentative conclusions about some general trends in hammer construction during that time.

ddf

I'm still not convinced of this point. Oils evaporate, very very slowly (look at the first ten entries on oil evaporation in a google search), as might whatever else is in felt.

There is evidence that vapors are being released by hammers for many years: just smell them. The vapors you smell are particles which are being lost by the hammers. Vapors over the course of decades or a century might well add up to a significant loss in mass.

The same applies to wood.

Well, let's go at this from another angle; just how much "oil" do you think is left in hammer felt after it has been heavily processed to, among other things, remove the "oils" that were in there? A percentage in terms of starting weight would be good. For this to be a significant factor the processed felt must have started out with some significant amount of oil. Where has it been hiding?

The same with wood; at the beginning just how much "oil" is in there to evaporate over the decades? That would set the limit to how much weight loss might be attributable to this factor. Again, a percentage in terms of starting weight will do. Again, for this to be a factor there would have to have been some significant amount of oil in the wood back in the beginning.

ddf

I once heard that Helmut Abel GmbH knows something about hammermaking . . . they seem to think that older hammers had oils in them:

"For the past three years Helmut Abel GmbH, their felt supplier and Brooks, Ltd. have been working on a new felt that would be more like felt as it was many decades ago. . .

What’s Different about Felt?

Modern felt is cleaned with an acid to remove foreign matter and give it a white clean look. The new natural >Felt is not cleaned with any harsh chemicals. It retains its natural, lanolin and oils. The wool fibers keep their natural appearance, exceptional resilience, flexibility, and silkiness to the touch."

Kidding aside, I have no idea about what the starting percentage of the weight would be. And, I don't doubt what you say about action ratios. I'm just saying there may be some loss of mass from long-term evaporation.

My question remains the same; in terms of weight just how much “natural oil” is in the felt at the time of pressing? For the evaporation of “oil” to have some significant effect on a hammer’s weight over time there must be some significant amount of oil (by weight) in the hammer at the time it is pressed.

We’ve been talking about hammer mass variations upwards of 20%; are you suggesting that either the hammer felt or the wood molding contained, by weight, anywhere close to 20% of natural—or any other kind, for that—oil?

ddf

Agreed: it would be a lot. 1-2 grams per hammer, if we're talking about oil, would be like having more than a cubic centimeter of butter in each hammer (at least in the bass).

Your information about the action ratios is more or less convincing to me. Using that information alone, we would have to conclude that either hammers have been manufactured lighter over the decades, or the touch was heavier in the early 20th century. (Aren't there records of touchweight from that time? Wouldn't it be possible to determine original hammer weight given the touchweight data and the action ratios alone?)

I had a Steinway Style 3 in the shop last year. It had an action ratio approaching 6.5 and the lowest hammer (A0) weighed in at about 8 grams. Even with that low a mass (Very little wear that I could see) the action ratio still demanded a LOT of lead weighting.

A modern, heavier hammer, would never have worked in this piano. Not without major modification of the capstan/wippen heel location or a new set of keys with a different balance rail location. I wish I had taken better notes on the piano, but it wasn't getting rebuilt, so I didn't spend the necessary time.

To my knowledge, wool contains about 10% wool grease (crude lanolin) - at best, 20%. Most of this is washed and spun out during the initial cleaning of the wool, and would not even reach the felt production stage. So, although this is a semi-informed guess, I doubt that felt would contain more than 1 to 5% grease - quite possibly less than 1%. And what's more, these greases aren't volatile - they don't just "evaporate". They are long-chain waxes with very high boiling points. (In fact, lanolin melts just above body temperature, so at room temperature, not only is it non-volatile, it's actually a solid wax.)

None of this answers the question of where the extra weight comes from.

No, but they are direct answers to the notion that in old pianos, "things dry out and lose weight", a notion that you yourself posted in this thread!

Except that actual data seem to be lacking.

Didn't some makers continue using lighter hammers much later in the 20th century? The OAR on my '74 Baldwin must be high since the key dip is just 9.5mm and if I remember right the strike distance is the standard 1.75". The (original) hammers feel almost like styrofoam compared to more dense hammers.

Well, Del mentioned a lot of data, and the conclusions that he drew from them.

For my part, I know that waxes such as lanolin don't evaporate at room temperature. I'm not planning to waste my time on an experiment to prove this. I suppose that given this glaring lack of data, we have to assume the notion that piano parts dry out and become lighter as they age, as the truth. You win!

Well, for my part, I am wondering where the weight comes from. I doubt that wood or wool fiber has become denser. Even so, hammer felt is graded by the weight of a sheet of felt, so a 14 pound hammer should have the same weight at any time, although the size of the felt may change.

As far as I have been able to determine the first really heavy hammers came from Japan starting in the late 1960s and early 1970s. By the mid-1970s replacement hammers from Japan—Imadegawa, etc.—became available and these were also relatively massive when compared to the hammers they were supposed to be replacing. Back in those days few technicians gave much thought to matching hammer mass when they replaced hammers so there were lots of pianos showing up with very heavy touch weights.

It took a while for the trade to figure out just what was happening. By then many of our replacement hammermakers were following the lead of the Japanese hammermakers and were pressing nice looking but very heavy hammers. I think, but could not prove, that Renner started pressing heavier hammers fairly soon after Japanese pianos started showing up with their heavier hammers. The current interest in evaluating action ratios and the relationship between hammer mass and key touchweight started during that period.

Baldwin was still pressing quite nice and relatively light hammers through the 1980s. By the time I started working for the company, however, they were trying to match the “power” of the Japanese pianos by making their own hammers harder. Since the U.S. felt suppliers were not making felt as dense as that used by the Japanese makers they were following Steinway’s lead and chemically hardening their hammers.

ddf

Del, your posts are as usual extremely informational -- thanks.

I have the impression that Ronsen hammers (at least the Weickert samples I have gotten my hands on) are not quite as low-density as the older hammers (in my case these are the original Baldwin hammers). The Ronsens seem to be between the densities of the asian hammers and the original Baldwin hammers.

I find this middle density to sound the best. I have one sample Ronsen on my Baldwin R and I can hardly get enough of that one note. (Of course I've heard the bacon are less dense yet -- appropriate for some pianos).

To the OP, I add my voice to those who suggest looking into the Ronsen hammers.

Obviously, wood has not become denser. Nor have wool fibers by themselves become any denser but felt—as it is felted for hammer making—certainly has. I don’t have any records from the late 1800s and early 1900s specifying just how thick or dense hammer felt sheets were, but according to conversations I’ve had with Bacon’s felt technologist and some of the older workers at Bacon felt, early hammer felt was not as dense as the felt Bacon was making in the 1980s (when I first visited their Taunton, Massachusetts factory).

I don’t know specifically how much denser Bacon felt was but at the time this increased density was considered a good thing and they were quite proud of the process that enabled them to achieve the densities they were getting. Within the structural limits of the wool fibers—and that must be pretty high considering the density of products like hard felt buffing wheels—felt can be made as dense as the manufacturer wants it to be.

We can tell only so much by analyzing original hammers from the period. We can measure the weight and physical size of the early hammers and compare this with the weight and physical size of modern hammers and make reasonably well-educated guesses. It is obvious—to me, at least—that most, if not all, earlier piano hammers were pressed from felt that was not as dense as the felt used to make modern hammers.

ddf

In terms of density, that’s about right. Hammers made with Bacon felt can be pretty soft; partly because Bacon felt is felted less and because of how Bacon orients the primary grain direction. They work best, in my opinion, at lower weights.

Both the Wurzen and Weikert felt seems to be felted similarly (in terms of density) but their voice is a bit different. The Weikert seems to have a little more resilience; a little more bounce. Since Weikert felt has only recently been reintroduced, it’s going to take a while for technicians to get used to it.

Even here, although Jack Brand, et al, have worked hard to re-create the original Weikert felt making process—using the hand-written notes of the supervisors and managers who actually made the stuff prior to WW II—there have been changes. To the preference of the hammermakers most of the modern Weikert felt now being produced is worked (felted) harder than the older felt.

ddf