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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=davner@kaosol.net href="mailto:davner@kaosol.net">Dave =
Nereson</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">Pianotech</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> June 02, 2003 2:03 =
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: hammers</DIV>
<DIV><BR></DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV> What?? The Steinways I've seen have =
always had
an egg-shaped hammer. Aren't we sposeta file trying to remove =
only one
layer of felt, or enough to remove the string grooves, without =
changing the
shape of the whole hammer (unless it's a grossly misshapen mess due =
to
someone else's botch job)? </DIV>
<DIV><FONT face="Comic Sans MS"
color=#000080></FONT> </DIV></BLOCKQUOTE></BLOCKQUOTE>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>Back in the =
"good old
days" the basic hammer shape was formed primarily in the caul, not on =
the
sanding machine. This is now longer the case with many modern hammer
makers.</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>Because of =
the way the
felt sheets were (are?) laid up the hammers used on early pianos, =
including
Steinways, did retain their original as-pressed shape through the =
sanding
process. It was possible to pick up and file off just one or two layers =
of
felt--indeed, for best performance it was necessary to file hammers this =
way.
</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>The felt =
used to make
hammers--at least in the US--starts out as a very wide and long =
continuous loop
of loose wool looking something like a diaphanous, or gauzy, =
</FONT><FONT
face="Comic Sans MS" color=#000080>conveyor belt. Once the loop is =
formed it is
built up by adding more and more loose wool in distinct layers until the =
desired
thickness and taper is obtained. Once the belt is built up to its =
desired
thickness and taper it is cut up into large sheets of appropriate size =
and
felted. During the felting process these individual sheets will compress =
quite a
lot coming out approximately the final desired size, taper and =
weight. They
are then cut to size and shipped to the hammermaker. The hammermaker =
will then
cut these sheets into tapered strips appropriate to the size, weight and =
shape
of hammer to be pressed.</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>As long as =
animal hide
glue was used to bond the felt to the wood hammer molding all hammers =
were
cold-pressed. It wasn't until well after thermal-setting adhesives =
(mostly
phenol-formaldehyde) were developed that heated cauls came into being. =
(And this
for faster press cycles, not because it resulted in better hammers.) =
Even after
pressing there remained in these hammers definite density gradations =
between
distinct layers that could (can) be picked up and followed by the =
careful
voicer. I have encountered some of these hammers with such well defined =
layers
it was very nearly possible to raise up a single layer and peel it off =
the outer
perimeter without using a sandpaper file.</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>It was the =
combination of
this felting process combined with the cold press, the properly shaped =
press
caul, the properly cut hammer strip and probably a hundred other details =
that
gave these hammers their wonderful resilience and tone qualities. =
Steinway still
uses a similar felt but for reasons of their own now seems to find it =
necessary
to heavily sand their hammers to shape. Whether this is because the =
desired
shape has changed or because the shape of the cauls or the shape of the =
hammer
strip has changed, I do not know. What I do know is that when using this =
process
to make hammers it is vital that you not sand through the individual =
layers on
the shoulders of the hammers and leave those over the crown unsupported. =
When
this happens the felt around the crown loses its foundation and quickly =
loosens
up, acting then as a damper between the string and those deeper
under-layers that are still under considerable tension. Once this =
happens piano
tone goes dead and out comes the lacquer. But those hammers will =
never
sound the same again.</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" color=#000080>With what I =
call
<EM>hard-pressed</EM> hammers, i.e., those pressed with relatively damp =
felt
under relatively high pressures and using highly heated cauls, any =
layering that
might have been present in the original felt tends to disappear. It's =
kind of
like steam pressing your wool slacks. The wrinkles disappear under the
combination of heat, steam and pressure. The wool fibers are literally =
reformed
and take on a much more homogenous mass. With these hammers it doesn't =
seem to
matter much if they are filed to shape or pressed to shape. You can cut =
across
the grain line with impunity and not worry overly much about what will
happen.</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080>Del</FONT></DIV>
<DIV dir=ltr><FONT face="Comic Sans MS" =
color=#000080></FONT> </DIV>
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