"pulley" keys

[Lance Lafargue]

Hi Newton,
1)The angle of the hole is drilled at an angle
   like->   front of key    /    back of key    ?

2)So how high should the key be lifted to "know" when the performance is not
   affected and friction is not introduced?

I did not know that the key should be "snug".  I was taught to ease it_very_
slightly larger than the pin.  And I thought I at least knew how to ease
keys!  %~)  Thanks,

Lance Lafargue, RPT
Mandeville, LA
New Orleans Chapter, PTG
lancelafargue@bellsouth.net



-----Original Message-----
From: owner-pianotech@ptg.org [mailto:owner-pianotech@ptg.org]On Behalf
Of Newton Hunt
Sent: Tuesday, January 02, 2001 9:37 AM
To: pianotech@ptg.org; hsrosen@gate.net
Subject: Re: "pulley" keys


>  I've never had anyone tell me why this is a bad idea....

It is not a BAD idea but...

The key hole is not drilled "straight" but at an angle to
the bottom of the key, about seven degrees or so.  The
purpose of this is to allow the key to be lifted in the
front without stressing the hole.

You are crushing wood, which can return later and be eased
again later.  If you remove wood would not have that option.

The hole should be conical in cross section so the bottom os
the hole grips the pin and the upper section allows the pin
free play when the key is played.  The Yamaha CF tool
permits making this shape from the top side.

Mr. Rosen is introducing lateral key movement by easing only
the outside walls of the hole.

Larger pins require less "effort" to ease to fit.  There was
a good reason S&S used to use a .163" pin.  Smaller pins
require a much tighter tolerance to prevent "chucking".
Hard woods with lots of oils in them work best, like lemon
wood, rosewood and a few others because of the natural
lubricity of the wood work best as "soles".

Saliva works well to shrink overly large holes, better than
water, but don't ask me why.

With polished pins and well lubricated holes and pins the
fit can be tighter.

A "perfectly" loose hole is not required.  The key bottom is
not a moving part as such but a pivot point so the fit can
be a little tight without effecting performance or unduly
effecting friction.
--
		Newton Hunt
		Highland Park, NJ
		mailto:nhunt@jagat.com