[pianotech] Square grand Key pins and Backchecks

[Joseph Garrett]

Below


> [Original Message]
> From: Terry Farrell <mfarrel2 at tampabay.rr.com>
> To: <joegarrett at earthlink.net>; <pianotech at ptg.org>
> Date: 5/31/2012 1:54:19 PM
> Subject: Re: [pianotech] Square grand Key pins and Backchecks
>
> > Joe Wrote: As for the Backchecks, here's how those are made: a piece of
leather,
> > similar to thin shoe leather on the back & front, glued around a
flattened
> > wire w/serrations. Then, (and this is variable from piano to tpiano), a
> > medium thick piece of what I used to get from Pacific Piano Supply as
> > "Understringing Felt". It is softer than the Upright backcheck felt and
> > less than the normal 1/4" thick. After that, there was usually something
> > like thick Elk hide, suede side out for the tail to check on. 
>
>
> These backchecks do not have the last layer of leather like you described
- "like thick elk hide". There is nothing to suggest that there ever was
any leather on the checking surface. These hammers have been checking on
the dense-ish felt surface. You stated that there was "usually" a leather
layer for the checking surface - was it sometimes just the felt?

Short answer: Yes. The only consistency, was a total lack of
consistency.<G> If it needs to be replaced, try to match what is there.
Since there is very little mass in square grand hammers, it doesn't take
much to stop them in check. Since it is a Single Escapement Action, there
is no springs/levers resisting checking, as in Grand Actions. There is a
bit of "spring", if you will, from the backcatch wire, that's all.
>
> > Sometimes the
> > whole thing was all leather and the softer stuff was usually Rabbit.
>
> I don't understand what you are referring to: "the softer stuff was
usually rabbit". What softer stuff? Where was it?

If there was a softer, more flexible leather, it was usually Rabbit. Rabbit
tends to separate, so it wasn't used much.
>
> Thanks again!
You'reWelcome, (again<G>). Glad I can help. It's always a pleasure to work
with someone that wants to do it right!

>
> Terry Farrell

Regards,
Joe
>
>
> > Other item is backchecks. Looks like the originals had two layers of
> > leather on the back and then on the front, one layer of leather and
then a
> > thick layer of dense felt - something like hammer felt. Anyone know what
> > type of felt this is - and a source?