1/2 punching

[David Ilvedson]

Well, that's what I have on this Bechstein E...strikeweight of 6.0...the veneer shim sounds better...so the problem is the key leverage?   The KR averages .52...I would have to move the capstans to improve it otherwise?

David Ilvedson, RPT
Pacifica, CA  94044


----- Original message ----------------------------------------
From: "David C. Stanwood" <stanwood at tiac.net>
To: pianotech at ptg.org
Received: 8/5/2006 4:20:01 AM
Subject: Re: 1/2 punching 



>>What is the thinking on cutting the balance rail punching in half, i.e on 
>>the backside of the key only?
>>
>>David Ilvedson, RPT

>Hi David

>Sorry to jump in on this so late...  this is a trick that the Precision 
>TouchDesign installers group has been using for about a decade.  It makes 
>the action dynamically lighter by lowering the overall ratio or heavier if 
>you cut off the back half of the punching and heavier if you cut off the 
>front half.  Chris Solliday presented the half cut punching method in the 
>two day action regulation class in Rochester.  The method came to me in the 
>mid 90's when I had been working on an action that had been in a very wet 
>storehouse for many months...  After thoroughly drying out the action I 
>repinned, lubricated keybushings, etc... friction friction friction I 
>thought..  I live on an island and I was putting the action together to 
>take it to the client and my boat was leaving in 2 hours... well when I got 
>the stack on and ran my fingers across the keys it felt heavy... I had 
>ASS-U-MEd that friction was the only problem... I did a quick check on the 
>strike weight ratio and found it to be above 6.0.  TOO HIGH!  The necessity 
>of having to catch my ferry kicked inventiveness into gear and I put a 
>little glue on the bottom of the key just in back of the balance hole and 
>put the key down on the key pin.  When the glue dried I took off the key 
>and cut the front half of the punching.  I found that the overall ratio 
>dropped by about 0.4, Enough to significantly lighten the dynamic feel of 
>the action.  I treated all the keys this way, made my ferry boat, and the 
>client was happy!

>I shared the technique with my PTD installers group but we were 
>trepidatious about the punchings coming unglued when fictitious technicians 
>in the future had the keys off the frame for maintenance.  In 2004 Steve 
>Willis at the Callahan piano shop in Oakland, came up with a more 
>transparent method of using a veneer shim on the balance rail.

>http://www.stanwoodpiano.com/RatioShim.htm

>The trade off is that you get a slight movement of the key on the pin and 
>one might think this will lead to problems of chucking in the long run but 
>we have not seen this.  I have seen 100 year old Ivers and Pond 
>uprights  that have balance rails set up like a bridge pin with the rail 
>cut away to the center of the balance rail pin.  The key rocks on the rail 
>behind the pin with slight movement on the pin.  These 100 year old pianos 
>exhibit no enlargement of the hole from the slight movement.  So we don't 
>consider that to be a problem so long as the pin is shining and smooth.

>I noticed in Rochester that Jurgen Goering at Piano Forte Supply in Canada 
>was selling cloth balance rail punchings cut just to the edge of the 
>hole,.... enough to reduce the ratio while leaving something to keep the 
>punching on the pin.  His feeling was that the punching would have no 
>reason to rotate once in place and said it was an old technique.

>Maybe Jurgen can share some of his history with the technique.

>Regards,

>David Stanwood

>