capstan spacing

[Fred Sturm]

--On Thursday, August 5, 2004 9:39 PM -0400 Wimblees@aol.com wrote:

> In a message dated 8/5/2004 8:07:55 PM Central Standard Time,
> awright440@cinci.rr.com writes:
>
> If keys are warped, is it possible to straighten them out, and if so
> how?
>
>
> I've been told to heat the key, and while the wood is warm, twist it in
> the direction it needs to go, then take away the heat. (Just like bending
> shanks.) I have tried to do this several times, but have never been able
> to successfully do it.
> Maybe someone else has a better idea.
>
> Wim

	Actually I do have what I think is a better process. Easier to show than 
describe, but I'll try. I use a jig consisting of a length of 2 x 4 with a 
small wooden block in the center. I clamp the key to the block (and 2 x 4) 
using wooden handscrew clamp (could be done with a c clamp and block just 
as well). The idea is to immobilize the key at the balance hole, but 
support it out a ways on both sides to avoid undue stress on that weak 
point. The balance hole portion of the key should be centered on the block, 
and the hand screw or c clamp block should straddle the balance hole.
	I then place a wedge of the proper height and angle between key and 2 x 4 
toward the end of the key, engineered to make the key twist in the 
direction I want it to go. Or, if all that is desired is a straight bend, I 
place a square block similarly. The block or wedge should be sized and/or 
shaped to allow the key to move in the desired direction about twice the 
distance you want it to end up.
	Then I clamp the end of the key to the block or wedge, and apply steam 
with a steamer (travel steam iron by preference, or a teakettle spout. I 
find the pressurized steamer puts out too much pressure and not enough wet 
and heat). Give it a good long shot of heat and wet. Follow with a heat gun 
(mostly to dry it and speed up the setting of the wood). Allow to cool and 
remove the clamp. Measure to see whether you got the results you wanted (I 
forgot to mention measuring before clamping, so you know where you were 
when you began).
	If necessary, reclamp, maybe with a shorter block or greater-angled wedge 
and resteam. Or, if you went too far, it's usually very quick to get back 
to where you were. I'll say that this procedure is usually reliable, though 
sometimes I have needed to redo it. So I have learned to aim at a little 
beyond where I really want to end up, figuring the wood will tend to move 
maybe 1/3 the way back toward where it was.
	I should also note that I have had some rather disastrous results with the 
method Wim described, trying to twist too hard (breaking the key) and 
various bad experiences with cutting kerfs and inserting wedges. Sometimes 
I succeeded, but more often had a mess to try to rectify.
	I haven't used the method I described above enough to feel really 
confident about its permanence, but results so far are encouraging. It is, 
at any rate, the most controlled and controllable method I have ever come 
up with or heard of.
Regards,
Fred Sturm
University of New Mexico