S & S 'A' parts, geometry -- shanks and flanges

[Richard Moody]

----------
> From: Dave Swartz <dms2000@PIONEERPLANET.INFI.NET>
> To: pianotech@ptg.org
> Subject: Re: S & S 'A' parts, geometry -- shanks and flanges
> Date: Monday, October 05, 1998 11:54 PM
> 
>.I've taken readings from
> .357 to .395 in the same set!!!  Does it not also effect the
relationship
> from whippen centerpin to hammer flange centerpin?...Where's that
knuckle
> supposed to be at rest?
> 
> Dave Swartz, RPT
> dms2000@majesticpiano.com
 
Dave, 
	If you mean a varation in the diameter of the knuckle between .357 and
.395 I would notify the maker and insist on closer tolerences.  To put it
in prospective a varation of .038 is close to a .040 medium thick
cardboard br punching, or almost 1mm.    
Also where the knuckle is at rest is where it puts the  hammer hammer at
the correct striking distance.  Which begs the question, "What difference
in striking distance is caused by a varation of .038? If the ratio is one
to seven, then the furtherest two hammers will be from each other is 7mm. 
 
	Now 10mm is .3937, I am wondering what size knuckles were installed. 
	I think of where the knuckle is placed on the shank is how far the jack
has to move up and down to make the hammer move X distance. I am not sure
how the size of the knuckle affects this distance, since every thing is
measured from the center line of everything, and distance traveled (which
is always circular with levers) is determined by distance from center of
rotation. (a radius) 

Richard Moody