Touchweight

[David ilvedson]

> Date:          Thu, 26 Mar 1998 19:41:38 -0500 (EST)
> To:            pianotech@ptg.org
> From:          Dave Swartz <dms2000@PIONEERPLANET.INFI.NET>
> Subject:       Re: Touchweight
> Reply-to:      pianotech@ptg.org

Check friction first!  Centers, capstans, keypins/bushings, 
repetition lever/knuckle (what kind of condition are the 
knuckles in?) and rubbing parts.  Downweight minus Upweight 
divided by 2 gives you the friction.  Around 12 to 15 grams is 
OK...70 grams downweight minus 30 grams upweight divided by two 
gives you friction of 20 grams.  Friction problem there!  If you 
get friction in line then hopefully you will still have a high 
upweight which will mean weight can be removed from the hammer.  
Big Geometry problems are not too likely in a Yamaha?  I'm sure 
the List will let me know about that...You might measure the 
distance from the front of key to the middle of the balance pin 
and from the middle of the balance pin to the middle of the 
capstan.  Should be 2 to 1 ratio...I use a 1" belt sander to 
remove weight from hung hammers.  Work on the tails first with a 
sample or two but the most bang for your buck comes from the 
sides of the hammer...

David Ilvedson, RPT 
Pacifica, CA
> At 08:47 AM 3/26/98 EST, you wrote:
> >
> >Howdy list,
> >
> >I will be attempting to reduce the touchweight of 70g on a 30 year old Yamaha.
> >Any advice?
> >
> >John LaBorn, RPT
> >
> >Elgin, IL
> 
> 
> 
> Remove the hammers???
> 
> Sorry, just had to do that!
> 
> Dave Swartz
> 
> 
>