[pianotech] capstain/wippen angle, was: key position at rest

[pmc033 at earthlink.net]

Can someone explain how drilling the hole in the middle on the half-round
Steinway balance rail block would negate the acceleration effect on the
hammer?  As far as I can tell, having the hole in the middle doesn't negate
the effect.  
What would change is the friction.  If the hole is drilled off center, it 
introduces some sliding friction due to the fact that the pin doesn't allow
fore/aft motion of the key.  At the end of the keystroke, the balance hole
in the key rides up the keypin because the fulcrum point has moved
backward.  If there were no keypin, the key itself would move backwards,
which would move the capstan contact point too. (Backwards meaning toward
the player).  Because of the keypin, the key cannot move fore/aft, but is
forced to slide on the half round.  It may be that the hole location was
changed because of the wear on the balance rail hole (caused by the keypin
rubbing against the hole )Drilling the hole in the center reduces the
friction (but doesn't eliminate it).  
In either case, whether the hole is here or there, there is an acceleration
effect.  Right?  Otherwise our good friends at Steinway have a lot of
explainin' to do.
	
	Paul McCloud
	San Diego


> [Original Message]
> From: V T <pianovt at yahoo.com>
> To: <pianotech at ptg.org>
> Date: 03/16/2009 8:07:41 PM
> Subject: [pianotech] capstain/wippen angle, was: key position at rest
>
>
> David, Paul, and Ed,
>
> Thanks for your comments. Indeed, the "accelerated action" patents date
to the mid '30s, but tilted capstans were already in use at S&S before that
time.
>
> Ed, interesting that the hole in the half round moved in later years; I
didn't know that it ever was off-center. An off-center hole would certainly
change the ratio during the key stroke.
>
> Vladan
>
>
>       
>