Let me also add that a hammer which is severely flattened on the crown has already lost some mass so our filing only adds to that. If our goal is to maintain the same BW as when the hammer was new (and it isn't always) then we should pay attention to that.
Original Message:
Sent: 07-03-2020 17:18
From: David Love
Subject: How much does filing hammers change their weight?
I'm responding to two claims, one, that filing is not significant and two, that you can't take off enough felt to make a difference without rendering the hammer unmusical. Both, I believe, are false and easily measurable. Removing .3 grams of felt is, in my opinion, a relatively light filing.
Actually, the accurate way to do this is to measure the strike weight before and after. I'll do that later and post the results. But from experience I can tell you not only is it significant but it can be very significant! In the 90s you may recall, Steinway produced hammers of the genus puffballus giganticus. I still run into those pianos. It was routine with many techs to do a very heavy filing not only to improve the tone (challenging the unmusical claim) but also to lower the touchweight which tended to be very sluggish at that time. It was not uncommon to drop the BW 4-5 grams in midrange of the piano, more in the bass and, of course less in the treble. The reduced mass in the treble also helped with clarity and sustain by reducing contact time.
While I agree that a light filing does not make a large difference, it does make a difference and if the hammers are filed multiple times, well now we're talking real money.
Even so, ~2 grams (.3 x AR of 6, eg) is not insignificant. If we're asked to balance an action at 50 grams DW do we tell a customer, well I set it plus or minus 2 grams but that's not significant? I don't think so.
I'll do some SW tests later, when I have time, and post the results.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 07-03-2020 16:42
From: Fred Sturm
Subject: How much does filing hammers change their weight?
David,
I make no claims other than to have presented objective data, from actual field filing. In my work, this was a fairly extreme filing. (I am still rather puzzled by your repeated characterization as of it as a "relatively light filing.") If you care to examine what I did, I made it easy for you: I photographed each hammer I filed right next to its neighboring hammer in each case, before I took the after weight. And I took an additional photograph of the highest hammer I filed in place, attached to the rail, for a further perspective.
I'm sorry that the order of the photos I attached to my post was screwed up in the uploading process, and apparently that cannot be changed by the user in the editing menu. In order to get around that, I have done a second
upload of those same photos directly to the library, which process allowed me to place them in the correct order. Please take a look (it's quick and easy). I think you will discover that I matched the shoulder profiles pretty well, allowing for the presence of the staples, which limit the possible arcs.
Your photos, David, do, indeed, speak for themselves, and are also objective. They are, however, a fabricated scenario, not one from actual practice. They mimic what we may think we do. And it is quite likely that your hammer felt is denser than mine - looks like Renner rather than the Steinway hammers I filed.
Does filing have an impact on touch, response, inertia, etc.? Yes, of course. How much effect does it have in the ordinary course of our work? That is what I have aimed at showing. I provided one example, and an easy one for anybody with a scale to replicate.
Rather than presume, based on conjecture, I suggest we measure, and specifically measure the results of what we actually do. Pretty simple concept.
Original Message:
Sent: 7/3/2020 3:54:00 PM
From: David Love
Subject: RE: How much does filing hammers change their weight?
The pictures I posted speak for themselves. Filing can contribute to a significant reduction in weight without them being rendered useless for music making, as Juergen posted. As your experiment suggested it may depend on how you file them and, of course, it depends on where in the scale. If you try and recapture the original shape, removing material from the shoulders, that will be more significant than, say, just flattening the high shoulder. But I stand by my statement that I would not underestimate the potential effect of hammer filing especially over time and multiple filings. Even if reduction in touchweight of 2-3 grams (.4-.6 grams of felt) is not insignificant considering techs do differentiate as significant setting the BW between 35 and 38 grams, not to mention the impact on inertia. And there are other factors. Even a relatively light filing as you have done can impact the repetition spring, for example.
Most of these significant reductions will happen over time and multiple filings. But I encounter that all the time on old pianos with original hammers where the BW is around 30 grams, certainly nothing near the original setting.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 07-03-2020 14:57
From: Fred Sturm
Subject: How much does filing hammers change their weight?
David,
Actually I posted three hammers, from bottom tenor, top tenor, and mid treble. I was surprised and interested to find that each of the three was reduced in mass by 0.3 gr. I wouldn't call it a light filing when the grooves are at least 10 mm long.
Regards,
Fred Sturm
"Since everything is in our heads, we had better not lose them." Coco Chanel
Original Message:
Sent: 7/3/2020 12:19:00 PM
From: David Love
Subject: RE: How much does filing hammers change their weight?
Depending on the section of the piano most of the weight is in the felt, not the molding. It's quite easy to take more than a gram of felt off in certain parts of the piano, especially with multiple filings over time. Fred posted a treble hammer that got fairly light filing. Of course the change in the top of the piano where the hammers have less felt will be less. But here's an example of just how much things can change.
The outer layer of felt on this hammer, easily removed by filing, is 1.4 grams. On a AR of 6 that' 8.4 grams and the impact on inertia is perhaps more significant. I would not underestimate the impact on touchweight and touchweight dynamics by filings, especially multiple filings over time.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 07-02-2020 16:11
From: Jurgen Goering
Subject: How much does filing hammers change their weight?
I am not sure this is a very precise method\. I have seen new hammers that varied by 1 gram form one hammer to its neighbor. Also, the core, which is significant in the hammer weight, changes dimension if you go up or down by a few notes.
Here is a jig I built for weight reduction by tapering hammers on shanks. It was a bit of a job to build but it works well. I put 2 hammers in it at a time. Left side of one, right side of the other gets trimmed on the table saw. The holes in the jig are calculated for maximum aerodynamic efficiency ;^)
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Jurgen Goering
Original Message:
Sent: 07-02-2020 03:07
From: David Love
Subject: How much does filing hammers change their weight?
The simplest way to do this is just take a hammer out of a set and weigh it and then find a hammer higher in the scale that weighs a gram less and compare the sizes of the hammers. The difference (assuming the hammers are the same width) is all felt.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 07-01-2020 13:51
From: Jurgen Goering
Subject: How much does filing hammers change their weight?
I, too, have often wondered about how much of an impact hammer shaping has on hammer weight and touch weight.
In a much more primitive experiment that yours, Fred, I grabbed a few hammers to see what one gram of felt removal actually looked like. Instead of filing (and trying to collect all the fuzzy and floating bits, I took the sharpest knife I could find and carved off a layer of felt, trying to maintain a semblance of hammer shape as much as possible. It made it easy to weigh the removed material. By the time I had removed enough felt to constitute one gram, there was not enough left of the hammer for any kind of reasonable music making.
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Jurgen Goering
Original Message:
Sent: 06-25-2020 15:32
From: Fred Sturm
Subject: How much does filing hammers change their weight?
The Steinway hammers in the photos are relatively "soft" pressed, certainly softer than Hamburg. I'll comment that filing is limited to the area above the staples, hence will not remove lower shoulder felt. Thus, visual comparisons with hammers an octave higher might or might not correspond to the same mass.
I simply offered the results as a way to document actual fact rather than assumption or extrapolation. I figure that in the absence of Ron Nossaman, somebody needs to do that once in a while :-)
Regards,
Fred Sturm
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
Original Message:
Sent: 6/25/2020 3:22:00 AM
From: Delwin Fandrich
Subject: RE: How much does filing hammers change their weight?
How would you rate the density of the felt in these hammers? Physical size notwithstanding.
In my experience -- but not having weighed the results as you have -- there will be more variation in hammers that started out life as hard-pressed, dense, and relatively massive hammers than you have found in these hammers.
Again, without having weighed and recorded the results, I have treated dense 'Asian' hammers with a mixture of alcohol and water, had them swell and, when dry, sanded them back to original size. Listening to the result and repeating the process several times until the hammers would no longer swell appreciably. At this point I found that I could remove one or more leads from the keys and still have a static downweight in the 50 - 54 gram range.
This goes back four or five decades and our methodology was rather crude so I'm sorry I can't be more precise, but I suspect the results achieved -- the reduction in mass -- will depend somewhat on how the hammers were originally pressed.
ddf
Original Message:
Sent: 6/24/2020 12:47:00 PM
From: David Love
Subject: RE: How much does filing hammers change their weight?
It depends on how much filing. In this case, with upper scale hammers that you've shown, it's not much. But it can be, especially with hammers lower in the scale where the strike point has gotten even wider and significant material needs to be taken from the shoulder of the hammer to recapture the original overall shape. And with multiple filings over time the amount can become quite significant. Hammer weight differences between note 26 and note 88 (let's eliminate molding differences between bass and tenor/treble hammers) can be as much as 1 gram per octave. That difference is entirely the amount of felt on the hammer. It's not difficult with even one good filing on a flattened hammer to reduce the hammer size by one octave, effectively. That's 5-6 grams of static weight and perhaps more significant in terms of inertia. While we don't necessarily have to worry about recalibrating touchweight with one relatively light filing, over time it's worth considering if that becomes an issue with the player.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 06-22-2020 15:46
From: Fred Sturm
Subject: How much does filing hammers change their weight?
The notion that filing hammers has a big impact on their mass, thereby impacting strike weight and key weighting, is fairly common. I have been skeptical from my own experience, noticing that when I gather pretty much all the felt from a major hammer filing and weigh it, it is generally less than 5 grams (divided by 88 to get an average). I have also filed to reduce mass, while also doing things like remove staples, cut wood from the moldings, and increase the taper. Filing didn't get much bang for the buck.
Last week I had a major hammer filing job on a Steinway B, original hammers, never filed in over 15 years of heavy use (from a piano prof's house, of course), so I thought I'd quantify this more precisely. The hammers had an average groove length in excess of 10 mm through the mid treble. I removed one hammer assembly each from bottom tenor, top tenor, and top treble, weighing them before and after filing. Result? I removed 0.3 gm from each, thereby reducing DW by about 1.5 gm.
I'm attaching photos to document this. For each hammer, I photographed it with a ruler to show the groove length, on the scale, with its neighboring hammer after it had been filed (for comparison), on the scale after filing. And there is a photo of a filed hammer between unfixed hammers to give a good context.
I hope this may be helpful for purposes of adding real data to picture of a very common part of piano service.
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Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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