Touchweight query

[Farrell]

David Love gave a good explanation of managing action component balance weights. You state "And there is freedom in the key bushings." Have you measured key bushing friction? If you have simply removed the stack and lifted and dropped the key fronts and see that they go down easy, there can easily be more than four grams of friction difference and you would not see it. If you have not precisely measured key bushing friction in each key, I recommend that be done. You may be surprised.

Terry Farrell
  
----- Original Message ----- 
From: "Keith Roberts" <kpiano@goldrush.com>
To: <pianotech@ptg.org>
Sent: Sunday, June 30, 2002 12:36 AM
Subject: Re: Touchweight query


> My thought is the key bushings. Uneven wear causing the extra friction.  Try
> some protec on the offensive key bushings. Just a guess.
> Keith R
> ----- Original Message -----
> From: <kam544@flash.net>
> To: <pianotech@ptg.org>
> Sent: Saturday, June 29, 2002 7:30 PM
> Subject: Touchweight query
> 
> 
> > List,
> >
> > I am reviewing some fundamental principles in downweight/upweight
> > [UW/DW] concepts and have come across a minor puzzle in this older
> > vintage grand piano.
> >
> > Two notes:
> > 1) one reads 48 grams DW, 28 grams UW
> > 2) one reads 56 grams DW, 28 grams UW
> >
> > My interest was to have the 56 gram DW number be closer to the 48
> > gram UW number without adversely affecting the 28 gram UW number.
> >
> > However, this is where my minor puzzle begins.
> >
> > Some information:
> > Hammer flange pinning is equal on both, wippen flange pinning is
> > equal on both, capstan to wippen heel appears to be satisfactory,
> > knuckle/rep lever appears to be okay. And there is freedom in the key
> > bushings.
> >
> > Additional information:
> > The weights of the hammershank assemblies of both notes respectively
> > are 16.4 grams 16.1 grams.
> >
> > The weights of the wippens assemblies of both notes respectively are
> > 20.1 grams 20.8 grams.
> >
> > I seem to be unable to accomplish my interest. Any ideas?
> >
> > At your convenience,
> >
> > Keith McGavern
> > Registered Piano Technician
> > Oklahoma Chapter 731
> > Piano Technicians Guild
> > USA
> >
> 
>