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Knuckle position and leverage
#2891407 09/17/19 04:03 PM
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I am trying to solve what feels like a leverage problem on a Steinway M and am considering my options. The action weight is a bit too heavy but that doesn’t feel like the fundamental problem. (I posted another thread about the piano but I thought this topic was specific enough to deserve its own thread.)

With WNG shanks, changing the knuckle position is a small ordeal compared to wood shanks. So I was curious if changing the knuckle position is a reasonable approach to increasing leverage and increasing controllability?

I’m assuming moving the knuckle closer to the centre pin will increase the leverage. I think there’s one more ‘slot’ I could move it in that direction (about 1mm).

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Re: Knuckle position and leverage
jsilva #2891427 09/17/19 05:17 PM
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Moving the capstan usually is what i do. But, I only move it after its verified with the "Weightbench "system by Fandrich-Rhodes. Other than that, with new hammers I am usually focusing on lightening the hammers.
-chris


Chernobieff Piano Restorations
"Where Tone is Key"
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Re: Knuckle position and leverage
jsilva #2891506 09/17/19 10:49 PM
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Well assembled piano actions seldom have "leverage" problems that are not best adressed by dealing with the hammer weight and front key weights first.


In a seemingly infinite universe-infinite human creativity is-seemingly possible.
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Re: Knuckle position and leverage
jsilva #2891525 09/18/19 12:07 AM
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Thanks for the thoughts!

Ed, what I’m feeling doesn’t appear to be related directly to weight. The touchweight was a bit too light prior to me replacing the hammers and this issue was still there. So I’m less concerned about touchweight at the moment since I think it’s something else.

I did use some vs-profelt on the felt at the bottom of the whippens which mostly got rid of the compression. The issue was improved a little bit. In the other thread pwg suggested adding felt strips there to help further.

I was at the piano today and realised I could probably move the knuckles a lot easier than the capstans, so I thought I’d ask people’s thoughts.

Re: Knuckle position and leverage
Chernobieff Piano #2891532 09/18/19 12:48 AM
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Originally Posted by Chernobieff Piano
Moving the capstan usually is what i do. But, I only move it after its verified with the "Weightbench "system by Fandrich-Rhodes. Other than that, with new hammers I am usually focusing on lightening the hammers.
-chris


It may be quicker and easier to move the action stack. And, it's easily reversible.
If you move the action stack forward ~1/16" to 3/32" you'll get a noticeable difference. You can try it and see if you like it.

When replacing the hammers, you hang the hammers out/in an equivalent amount. If not, you have to move the location of the key frame by using the guide brackets in the key end blocks. you have to keep the strike line -- especially in the treble.



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Re: Knuckle position and leverage
kpembrook #2891588 09/18/19 08:37 AM
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Interesting idea kpembrook. I’ll do that next time I’m there.

I’m guessing there aren’t many thoughts on moving knuckles since traditionally they would have been quite an ordeal to move smile Or maybe moving them would do very little?

Re: Knuckle position and leverage
jsilva #2891598 09/18/19 09:04 AM
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I should reiterate that my key point here is--I do not make any changes until its proven first. I have two ways to do that. One, is that I have the Fandrich-Rhodes Weightbench system. Two, I have an adjustable grand action model to test the relationships. Often i use both. Otherwise you are just flying blind by changing things around.
-chris


Chernobieff Piano Restorations
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Re: Knuckle position and leverage
jsilva #2891599 09/18/19 09:05 AM
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Well, the problem is that you are kind of guessing as to the source of the problem. It's a little unwise for any of us to make a geometric suggestion (hard to reverse) without actually being able to analyze the situation.

I did suggest "bolstering" the capstans cloth. Do you understand what I mean by this? If so, just do one somewhere and see what it does. If you need further clarification it can be provided. The general idea here is to bring things back as close to their original profile as possible (IOW eliminate the effects of wear) and then determine the geometry issues.

Keep in mind too that no matter who made the piano, it was designed to operate reasonably well for about 30-40 years. After that the design intention would be new parts all around.

Pwg


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Re: Knuckle position and leverage
jsilva #2891736 09/18/19 03:18 PM
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Thanks Chris and Pwg! I’m not meaning to guess, and if I were to move the knuckles I’d try it on one first (and there’s only one more slot it can move toward the centre pin so it wouldn’t really be guessing in terms of placement).

Pwg, I did understand what you meant about the cloth and I was planning on trying it. The vs-profelt did improve the situation a bit and so your idea would probably improve it even more. However, not knowing if it’d entirely fix the issue I am wanting to be prepared if needed.

As far as I can tell there are no modifications to the action. I’ve also lubed all of the friction parts (protek clp and teflon powder as appropriate). So I’m just trying to narrow down what could be causing the issue. It doesn’t feel like friction or simply too heavy, but it feels like effort.

Last edited by jsilva; 09/18/19 03:19 PM.
Re: Knuckle position and leverage
jsilva #2891836 09/18/19 08:08 PM
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If you bolster, here's what I do:

1) Thinnest bushing cloth I have (about .033") ripped to a strip about 1/8" - 3/16" wide.

2) Taper one end (as if to rebush a flange).

3) Apply CA to the tapered end to harden it (this will become your "needle")

4) After curing hard, sand or file this end to almost a sharp point.

5) With action upside down, lift a whippen and begin inserting the bushing cloth between the whippen cloth and whatever other cushion was originally installed. This should be an unglued area in the center of the cloth. Make sure you hold the whippen body carefully to resist the side pressure you are applying with the bushing cloth (you DON'T want to damage the pinning). As the tapered end protrudes through the other side grab it with tweezers and pull it all the way through till the end is flush, then cut it with a razor blade and go on to the next.

6) Rinse and repeat 87 times


This can have a significant effect on the action as it gets rid of most (or all) of the dimple created by the capstans and restores proper geometry to that portion. It should reduce friction further. Lasts a long time too (usually).

I am assuming this is either a SS or similar with a properly set up whippen cushion. Some makers glued their cloth all the way and therefore this will not work.

Pwg


Peter W. Grey, RPT
New Hampshire Seacoast
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pianodoctor57@gmail.com
https://www.youtube.com/watch?v=PK0T7_I_nV8
Re: Knuckle position and leverage
jsilva #2891856 09/18/19 11:04 PM
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Thanks for extra details Pwg! Definitely clear now, and a clever solution. I’m assuming no work has been done to that area. Everything in the piano seems original (except for the parts I’ve replaced).

Re: Knuckle position and leverage
jsilva #2896207 10/01/19 04:27 PM
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Ok, I was at the piano today and tried out Pwg’s suggestion. It was a bit harder than I thought to work it out but now I understand a lot better. One problem is that my bushing cloth is too wide even after cutting it in half. I also understand better how to make a decent tip. However, I see now that I need to sort that out before going to the piano so I only did one whippen today.

I think my bushing cloth sort of folded over on itself because it was slightly too wide and so it lifted up the cushion more than expected, but is it problematically too much?

[Linked Image]

Look at how much it raised the hammer smile

[Linked Image]

It definitely felt better but with just one done it was hard to know if it was enough. I’ll probably go back next week and do the rest.

Re: Knuckle position and leverage
jsilva #2896224 10/01/19 05:25 PM
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Greetings,
If those are Steinway hammers, I see one problem that might solve others. They have not been shaped, and appear to be carrying a lot useless, dead, felt, below the middle of the hammer shoulders. So, before you begin changing ratio, re-read what Ed McMorrow posted. You have to know what your SW is, and how appropriate it it to that piano. Then you can find out what ratio gives the response you want. The mechanical ratio is somewhat limited by the height of the plate, (you only have so much room for blow), and the accidentals, (which cannot bury under the naturals and cannot be more than 1/2" above. So, given the need for .035-.050" after-touch, and a maximum of .410" key-stroke, you have to figure out what ratio will keep the shanks off the rest felts, but not too much....

Front weights on model M's can rarely go above 35 gr. at A1, 25 gr. at C40, 15 gr. at F57, etc. With a ratio that works with the action cavity's dimensions, you can find out what weight hammer gives a good response.

You mention one more slot to move the knuckle closer to the pin, but that shortens the moment arm and will lead to heavier actions. If you have knuckles closer to the pin than 16 mm, you may find problems with insufficient clearance for the jack at check. If they are beyond 17 mm, you will have an excessively deep key-stroke or a very short blow.
Regards,

Re: Knuckle position and leverage
jsilva #2896231 10/01/19 06:04 PM
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Those are not Steinway hammers.


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Re: Knuckle position and leverage
jsilva #2896233 10/01/19 06:12 PM
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Jsilva,

Yes, it looks like your cloth was too wide. It cannot be more than 3/16". 5/32" better. I would remove that one and try again. No more than .035" thick. Just add to what is already under there. Too much and you risk popping the whip cloth loose on one side. You also should polish the capstans to a brilliant finish o a rouge wheel. Or better yet replace the brass with WNG aluminum. Almost weightless.

Remove the whippen from the frame to do this until you get a feel for it. I agree with Ed (both) on the hammers. Though they don't look like SS to me.

Pwg

Last edited by P W Grey; 10/01/19 06:13 PM.

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Re: Knuckle position and leverage
jsilva #2896235 10/01/19 06:28 PM
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Thanks Ed and Pwg!

They are 14# WNG (Abel) Natural hammers. I’ve been waiting to see what to do about removing some felt from the hammers until I solve what I’m feeling.

This issue was present with the previous (Steinway) hammers, and the action was too light then. It manifests itself in a large difficulty controlling quiet playing. I had assumed that the heavily worn knuckles were limiting the control, and also the tone could have been better, and so I replaced the hammers, shanks, flanges (WNG).

Control (and tone) is better but the fundamental problem still persisted. So that’s why I was considering other options for improving the feel, and to me it feels like a leverage issue.

Bolstering the cloth like in the photo did make a difference but as I said I can’t tell for sure with just one key. Once I bolster all of the cloths then I can make a better assessment (I’ll replace the one I did Pwg).

Re: Knuckle position and leverage
jsilva #2896277 10/01/19 09:53 PM
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Have you checked the action spread?

Pwg


Peter W. Grey, RPT
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www.seacoastpianodoctor.com
pianodoctor57@gmail.com
https://www.youtube.com/watch?v=PK0T7_I_nV8
Re: Knuckle position and leverage
jsilva #2896283 10/01/19 10:31 PM
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I haven’t... I’ll do that next time I’m there. Thanks for reminding me.


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