[CAUT] Re: swelling knuckles -- old thread

[Otto Keyes]

No, the friction reduction was not significant, nor was there a big change
in the rep. spring tension.  The odd one here & there needed minor
adjustment, but no more than one would find on a normal regulation check.
To the best of my calculation, it was the combination of the minute swelling
of the knuckles and compression of the felt on the jack reg. button that
caused the double strike.  I was just a rather curious (& unwelcome)
phenomenon that I hadn't anticipated.

Lesson learned:  You may not be able to teach an old dog what to do, but, if
the pain is great enough, sometimes they will learn what NOT to do.

Otto

----- Original Message -----
From: "Joseph D. Gotta, RPT" <tune@a440piano.com>
To: "'College and University Technicians'" <caut@ptg.org>
Sent: Thursday, May 05, 2005 6:32 AM
Subject: RE: [CAUT] Re: swelling knuckles -- old thread


> Was there a significant reduction in friction? If so did you find the
> repetition springs suddenly a little too strong? I have encountered this
> and had to relax the springs to alleviate double striking hammers on a
> closely regulated action. This was with powdered Teflon applied to the
> knuckles though so I'm sure there was no swelling involved.
>
> Joseph D. Gotta RPT
>
>
> -----Original Message-----
> From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of
> Otto Keyes
> Sent: Wednesday, May 04, 2005 4:14 PM
> To: College and University Technicians
> Subject: [CAUT] Re: swelling knuckles -- old thread
>
> Some time back I mentioned encountering a problem with bobbling hammers
> on a
> D after I had hit them with a shot of dry spray teflon, but then forgot
> to
> report the results.
>
> >From some of your suggestions I was afraid I was going to have to
> re-pin
> everything (fairly new parts), but the pinning turned out to be just
> fine.
> Though I don't know how much they changed, since I didn't measure just
> before the treatment, the let-off was consistently closer, so the
> knuckles
> had swelled just slightly.  This, coupled with the fact that the
> regulating
> button felt on the jack had compressed slightly, allowing it to sit just
> a
> bit deep under the knuckle, caused the hammers to double-strike.  Once
> those
> 2 elements were dealt with, it settled down to work like a real piano
> again.
> My guess is that something in the aerosol carrier in the teflon spray
> caused
> the knuckles to swell just enough to cause problems when put together
> with
> other minor deficeincies.  I doubt that it would have caused a problem
> had I
> just sprayed it on the balancier & top of the jack.
>
> Otto
>
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