Filing over-needled hammers

[Horace Greeley]

Kent,

Under the heading of "everyone will see this differently", please accept the
following thoughts - thrown in among yours for good measure - :


At 05:56 PM 10/8/97 -0500, you wrote:
>I have a bit of a situation with a B in the studio of a concert pianist.  
>The studio is a "voicing-intensive" situation and the hammers have been 
>over-needled with glover's needles.
>
>(FWIW, I don't use glover's needles and strongly recommend against them, 
>based on the damage I have seen done with them.  They slice hammer felt 
>open.)

FYI - There are a fair number of folks who have "grown up" using glovers
needles.
I don't for the reasons that you note - to amplify, the sharp triangular
design of
these needles is such that they cut the felt fibers perhaps even more than
they
wedge them open.  The result of using them is, in my experience, that the
damage
is fairly well hidden, if one has started with relatively new hammers, and
been most
judicious in voicing - not arbitrarily stabbing about.

If not, then, as you describe:

>A large number of these hammers are split open on the surfaces of the 
>crown on either side of the striking area.  Smooth shaping while filing 
>is impossible due to the fact that the wool that is pushed into the 
>crevices during filing strokes is not removed, and builds up as ridges.

What kind of hammers are these?  If they are hard and/or hot-pressed, you
may be
able to work with finer paper than I assume you are using.  It is not
unusual for me to
start with 220 and then work toward 400 or evern 600.  Also, do not be
afraid to use
a hammer iron to smooth things out, even as you go along.  I use an old 40
Watt Hale unit with
a formed brass head (lets one work around the hammer head), running through
a cheap
dimmer switch to control the heat.  The ridges start to form as you begin
to run contrary to
the grain of the folded (molded) felt, work back the opposite direction.
The main thing is going
to be to try to maintain what of the consistency of gradation of size you
can from one hammer
to the next, up and down the scale.  Digging in too deeply will only make
more work in the long
run.

>The piano does not sound all that bad yet, but my thoughts on this could 
>change if I get a phone message to the contrary in the next few days.

What is the absolute minimal amount you can get away with and still have the 
instrument sound not "all that bad yet"?  Is there enough shoulder left to
just
open the sound up a wee bit, thus really minimizing whatever you _must_ do 
on the crown?

>Obviously, the hammers will have to be replaced shortly, but I need to 
>keep this piano functionioning during the months that it will take to 
>schedule new hammers.

You weren't doing anything over Christmas break then, were you?

>I have considered soaking the hammers with an extremely dilute juice, 
>hoping that the fibers would hang together enough afterwords to 
>facilitate good shaping.

Yes, than _can_ help - or hurt. If you try this, I would suggest using 
lacquer sanding sealer diluted with lacquer thinner (as opposed to Acetone),
in a ratio of 10:l, thinner to sealer.  Four main reasons: 1) Sanding sealer
is a _very_ forgiving hardener, and breaks down (relatively) quickly under
use; 2) While the thinner will take longer (much) to dry than Acetone, that is
just the point - what you are trying to achieve in this (somewhat drastic)
procedure is the restoration of some semblance of homogeneity (as to
resiliance)
in the felt of the hammer.  Acetone may or may not remain active as a
carrier long
enough to accomplish this; 3) The hammers will require less of your time
afterward
with the needles, as the sealer is easier to penetrate; 4) (Finally) Sealer
will
produce less change in timbre of the instrument than other hardeners, with the
possible exception of collodion - and that, to be effective, must be
diluted with
Ether, the use of which I do not encourage.

>Any thoughts?

Actually, depending on how much "free" time you have at the Conservatory,
this is a set of hammers from which one could learn much, if they were in 
a place where one could really keep an eye on them...

I'd be interested to follow this one a bit...

Best of luck.


Horace Greeley

Systems Analyst/Engineer
Controller's Office
Stanford University

email: hgreeley@leland.stanford.edu
voice mail: 650.725.906
fax: 650.725.8014