[CAUT] knuckles & bobbles

[Otto Keyes]

Ed,

Okay, I misspoke here, & take your castigation with the proper
consternation; eyes downcast with furtive glances at the "RPT's Guide to
P.C. Technical Terminology", searching carefully for the inoffensive term.
;-)    I doubt that I'll succeed, mind you, but I'll try.

I really appreciate the helpful suggestions you have all offered, and will
indeed correct the problem with those in mind, praying that I don't have to
re-pin the whole thing!  Without getting into a lengthy explanation, during
which I'm sure I would manage to insert the other foot, what I was trying to
say was that, while there did not appear to be a knuckle dragging problem
(only my own) to impede the let-off, I would apply a bit of preventative
maintenance in the form of a quick shot of teflon to keep them free.  (By
the way Ed, your point is well-taken about the importance of the proper
amount of friction in the jack/knuckle contact point -- a point I regretably
forgot in the moment of transgression.)  This, of course, violated the "if
it works, don't fix it" rule, setting up the subsequent chain of events.

What piqued my curiosity here was the effect of the teflon spray on the
problem.  I expected it to have little, if any, effect, but merely applied
it as preventative measure to "keep things moving smoothly".  The results,
however, provided a bit of learning which came under the "Don't ever do that
again!" category, but I'm curious as to the "Why?" of the outcome.  I have
used the product "Dri-lube" in the past without any ill effects.  And as
such, I was wondering if any of you have had such experiences with this or
similar products, and/or possible explanations.

Thanks again,

Otto


----- Original Message -----
From: <A440A@aol.com>
To: <caut@ptg.org>
Sent: Thursday, March 03, 2005 5:04 PM
Subject: Re: [CAUT] knuckles & bobbles


> Otto writes:
> << Though there was not noticable friction on the knuckles, I decided to
put a
>
> little teflon on them in the form of a dry aeresol spray to speed up
>
> repetition.  >>
>
>    I am not sure of the logic here.  How is reducing the friction at the
> knuckle going to speed up repetition?
> Repetition is dependant first on the height of the backchecking and then
the
> speed of the key return, (not the speed of the hammer rising from check,
since
> at fast repetiton, the hammer doesn't move up or down until the jack is
once
> again under it).  Is the very slight difference in knuckle friction going
to
> increase the return speed of the key?
>    To my thinking, greater friction at the knuckle will cause there to be
> more spring strength for the same speed of the hammer rise when released
from
> check.  This additional spring strength may be of use in speeding the
key's
> return, so reducing it may actually hamper repetition.  There is virtually
no
> difference in key return speed between a spring that causes a smooth
steady rise
> and a spring that kicks the hammer up fast enough to feel it in the key.
>   If there are bobbles in the hammer, I would look first to let-off, then
to
> the interaction of the hammer tail and the backcheck and the friction in
the
> grub,(spring slot), and how much aftertouch you are allowing. Many times,
I
> have found bobbles when the spring was too strong for the system.
Hammershank,
> as well as balancier pinning is very important in this equation. If they
are
> too loose, the spring will be hard to regulate.
>    Going even further, a loose jack pinning will allow the jack to fly
back
> and forth uncontrollably, and it may be that repetition will suffer from
an out
> of control jack.  Since my eyes are not able to discern such rapid
movement,
> this is only a theoretical question.
> regards,
>
> Ed Foote RPT
> http://www.uk-piano.org/edfoote/index.html
> www.uk-piano.org/edfoote/well_tempered_piano.html
>
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