jig for Twisted-Key keytops

[Farrell]

Gotcha! If the key is twisted, the bottom is not planar. When you place the
bottom of the key on a planar drill press table (or other jig), it will not
lay flat, & hence the questions as to where the keytop is laying.

What about setting the key on a slightly elevated position where the key
forward end of the bottom rests on a rod or thin wooden riser (say 1/4" by
1/4" cross section, and 1" long) that is oriented perpendicular to key
length. This gets the front of the key off the table and gets the bottom and
top (at the key front) parallel to the table, and the sides perpendicular to
the table. Then use movable spacers of various suitable thicknesses (perhaps
1"x1"x1/4" and other near thicknesses) to place under the rear portion of
the key, moving the appropriate thickness spacer to an appropriate location
such that now the keytop is parallel to the table (the rear portion of the
twisted key will possibly not sit flush to the rear height adjuster). A
simple sliding block with an adjustable extension on top could be used to
quickly verify equal keytop height along the keytop length (similar in
theory to the Jaras jig to measure backcheck and hammer checking height). Or
it may be that you would want the rear support to be located at the center
pin hole. That would aid in ensuring that all keytop cuts are exactly the
same as they lie in the keybed.

I hope you can bear with my thoughts on this. I have encountered the same
problem, and am trying also to find a usable solution. Let me know.

Terry Farrell
Piano Tuning & Service
Tampa, Florida
mfarrel2@tampabay.rr.com

----- Original Message -----
From: "Paul McCloud" <smccloud@ix.netcom.com>
To: <pianotech@ptg.org>
Sent: Friday, March 17, 2000 12:09 AM
Subject: Re: jig for Twisted-Key keytops


> What I'm saying is that if the key is twisted, and you lay it flat on
> your jig, the keytop may not be exactly parallel to your jig surface.
> Try taking a key from a piano and lay it flat on a known flat surface.
> Especially old keys from a large upright.  Push down in the middle of
> the key.  Some keys will flex a little.  Maybe it's not enough to notice
> for most keys,  but if there's any twist in the key, your planed surface
> may not be parallel to the bottome of the key.
>     Paul McCloud
>
>