kneading hammers

[Barbara Richmond]

----- Original Message ----- 
From: "Rupert Williams" <obliquestrung at yahoo.com>
To: <pianotech at ptg.org>
Sent: Wednesday, May 30, 2007 12:12 PM
Subject: kneading hammers

Greetings Rupert:

> Please could someone give some advice on exactly how
> to go about kneading hammers as suggested by Alfred
> Howe in his book on Scientific Piano Tuning and
> Servicing (1947)?

That's a catchy title!  Can't say I've seen the book (or the movie).  :-)

> He mentions gas pliers, and kneading in alternate
> directions. Others on this group have in the past
> explained how they have used vice-grips.

Hmm, I'm not familiar with gas pliers, but I do know what vise-grips are.
>
> I would like to know exactly where to apply the
> pressure, and how much pressure to apply.  Should the
> felt thickness be reduced by 1/2 or some other
> fraction?

No, I don't think you want to reduce the felt thickness by 1/2 (whew!).  In
fact, I can't believe that anyone could responsibly say, reduce the felt
thickness
by "this much."   It all depends on the hammer, how hard it is, & what your
goals are.  When I've used vise-grips, the squeeze has been between, say,
1:30 and 3:00.  A small imprint is made on the sides and the hammer surface
is slightly cupped.  Then I proceed to needle the shoulders until the 
cupping
is gone.  This is one method to open up or increase the sustain on hard
hammers.
>
> Can the felt be permanently damaged?

Yes.  It is quite possible to ruin hammers with Vise-Grips.

>Is it inherently more harmful than needling?

I wouldn't say so--but yes, if it's over done.  It reduces the amount of
needling
one might need to do to get similar results.  I feel the advantage is speed
and ease--on the right hammers.

Be careful of mis-shaping the hammers.  Unless you really know what you
are doing, I would be very careful to avoid the strike point or the
area below  it.  In general, tread very carefully.  Just because a little
works, it doesn't mean a lot works better.

Off to work.  Good luck!

Barbara Richmond, RPT
near Peoria, IL