[pianotech] key bushing problem

[John Formsma]

David, I'd say you need a thicker cloth. However, it sounds as if you have
only three different sizes. (Thin, medium, and thick. ??) You might need a
larger variety of thicknesses. Are you using the mortise sizing cauls?

The first couple of times I did rebushing, it turned out the way you
describe. Those times I did not use the mortise sizing cauls. Now I do, and
most of those problems have gone away. And, I've learned (by trial and
error) how tight the caul needs to feel with the new cloth. It's definitely
a "feel" thing. Firm, but not difficult to press in. The way I do it, one
can lift up the key (at least slightly) by picking up on the caul stuck in
the mortise. You don't want it jammed in there, but it must be firm.

I have the 6 different thicknesses of cloth from either Spurlock or
Pianotek, but normally one size fits all now that the mortise sizing cauls
are used. I think it's the #2 cloth.

I don't do rebushing as regularly as some, but it usually turns out quite
well now that I've learned what not to do. :-)

--
JF

On Tue, Jan 26, 2010 at 8:08 PM, David Nereson <da88ve at gmail.com> wrote:

>   I rebushed a set of keys using the nylon Spurlock cauls. The pins were
> .146" so I used that size caul.  When done, the keys still wobbled laterally
> (balance rail).  This has happened a couple times now.  I had done no easing
> or ironing after removing the cauls.  Should I have used a smaller caul
> (even tho' the size I used is meant for that size pin) or thicker bushing
> cloth?  Or both?  When I initially determined what thickness cloth to use,
> by laying the trial cloth across the mortise and pushing a key pin into the
> hole, thick seemed way too tight.  Medium was just right (could be pushed
> in, but holding the key upside down, the pin would not fall out -- this is
> according to the Spurlock directions).
>   Once I steamed 'em all back out and rebushed with thicker cloth, but
> using the same cauls, and they still came out too loose (too much lateral
> play).  So do you use a smaller caul than the one intended for a given size
> pin?
>   --David Nereson, RPT
>
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