Touchweight Metrology Question

Jon Page jonpage@attbi.com
Fri, 17 May 2002 19:13:05 -0400


At 11:39 PM 5/17/2002 +0200, you wrote:
>Jon Page wrote:
>
> >
> > For instance, if your lower the SW of note 16 from 11.9 to 10.3.
> > The SBR is presently 5.8 (we'll call it 6).
>
>But Jon... his Ratio is around 5.5 for whites and close to 6 for blacks
>otherwise.  It would seem to me the average SBR for the whites would ask for
>about the SW he has.... or what ?

No, it stays the same because BW changes proportionally with SW alteration 
and consequently SBR.

Besides, so what. You will never get the SBR of the sharps and naturals 
equal unless you employ assist springs.
So the balance rail holes may be too close together, the front key lengths 
might not be ideally proportional,
knuckles are slightly askew. This is not late breaking news, from any 
manufacturer. For all practical purposes,
to lighten the hammers will simply bring the action into a comfortable 
playing level. We're not talking Carnegie Hall.

Moving the sharp's capstans forwards may help, but so far that level of 
expense has not been justified. Many pianos
have the sharp's KR .02 higher than the naturals. The question would be, 
does the jack presently have sufficient
clearance of the knuckle to support a reduction in wippen travel induced by 
capstan relocation. Not just what looks
good on paper. Bear in mind the effect of hammer wear on regulation in the 
future.

If the level of playing effort is still not acceptable to the church then 
further advice can be given to alter the geometry but
for all intents and purposes lightening the hammers is what will give the 
best results without replacing the wippens with
ones employing assist springs.

So it's either lighten the hammers or install wippens with assist 
springs.  Going around in circles about SBR, is just that.



Regards,

Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.
mailto:jonpage@attbi.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




This PTG archive page provided courtesy of Moy Piano Service, LLC