<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; =
charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1400" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY style="FONT-SIZE: 10pt; FONT-FAMILY: Arial; BACKGROUND-COLOR: =
#ffffff"
bgColor=#ffffff>
<DIV>Dale,</DIV>
<DIV>from mechanical view hammer stiffness does not simply follow hooks =
law.
Hammer reaction force is increasing nonlinear with felt =
compression. </DIV>
<DIV>Hammer stiffness can be described as a complex =
value by its
nonlinear elastic modulus. The real part is the reaction force =
on the
string and the imaginary part is the damping loss.This phenomen is =
called
"hysteretic damping".</DIV>
<DIV>Measurements on hammers parameters has been done by =
Anatoli
Stulov, where he measured felt stiffness and rebound time.He found
differences of a factor of about 100 % in the rebound time between
different new hammer sets made by diverse makers. (Abel, Renner, =
Imadegawa)
</DIV>
<DIV>The rebound time is in correlation with the =
felts
<EM>inner friction losses</EM> (or imaginary part of elastic modulus) , =
not to
<EM>stiffness</EM>.</DIV>
<DIV>A high quality felt has a low rebound time. Laquering, heat =
and
overpressing of the felt increases not only =
stiffness, but
also the rebound time (and therefore losses), since the
fibres become glued togehter. </DIV>
<DIV> </DIV>
<DIV>regards,</DIV>
<DIV> </DIV>
<DIV>Bernhard</DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=Erwinspiano@aol.com
href="mailto:Erwinspiano@aol.com">Erwinspiano@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, May 11, 2004 =
3:00 AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Lacquer fight! =
Lacquer
fight!</DIV>
<DIV><BR></DIV>
<DIV>In a message dated 5/10/2004 1:03:52 PM Pacific Standard Time, <A =
=
href="mailto:Richard.Brekne@grieg.uib.no">Richard.Brekne@grieg.uib.no</=
A>
writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
face=Arial>Hi Bernhard.<BR><BR>An interesting point that I see no =
one has
really answered =
too.<BR><BR>Cheers<BR>RicB<BR><BR></FONT></BLOCKQUOTE>
<DIV><FONT size=4> Hi Bernard</FONT></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
face=Arial>Bernhard Stopper wrote:<BR><BR>>Hammers parameters =
are not
only stiffness/springieness.<BR>>A big influence on sound quality =
is the
amount of the energy that is lost<BR>>due to the hammers inner =
friction
of the fibers.</FONT></BLOCKQUOTE>
<DIV><FONT size=3><STRONG>>>> Which no doubt is in direct =
correlation
with it's inate stiffness /sprininess or lack of =
it.</STRONG></FONT></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
face=Arial>A good felt quality has a<BR>>high ability of =
rebounding a big
amount of the input energy. </FONT></BLOCKQUOTE>
<DIV> <FONT size=3><STRONG>Providing it got adequate &
appropriate pressing resulting in tension &
compression.</STRONG></FONT></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
face=Arial>It seems logic<BR>>that this rebounding ability on a =
high
quality hammer is reduced by<BR>>lacquering. </FONT></BLOCKQUOTE>
<DIV> <STRONG><FONT size=3>To me This certainly seems to me to =
be the
misinformation of this thread but if you wish.... If so then a
hammer made with a good felt but is not stiff enough or to =
springy
for the tone desired then a 5-1 lacquer acetone solution ,or whatever, =
will
stiffen the felt & improve its rebound rate.</FONT></STRONG></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
face=Arial>On the other hand, it might be possible that on a =
hammer with
a<BR>>bad felt quality with excessive inner friction may be =
stabilized to
a better<BR>>level by lacquering.</FONT></BLOCKQUOTE>
<DIV><FONT size=3><STRONG>>> May I submit that the Inner =
friction
of felt has always been a fairly esoteric & small =
consideration
to the discussion of hammers even though it is a know factor & =
frankly to
me personally not very useful.</STRONG></FONT></DIV>
<DIV><STRONG><FONT size=3> Rgeards--Dale</FONT></STRONG></DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
=
face=Arial><BR>><BR>>regards,<BR>><BR>>Bernhard</FONT></BLO=
CKQUOTE>
<DIV></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT lang=0 face=Arial size=2 PTSIZE="10" =
FAMILY="SANSSERIF">Erwins
Pianos Restorations <BR>4721 Parker Rd.<BR>Modesto, Ca
95357<BR>209-577-8397<BR>Rebuilt Steinway , Mason &Hamlin
Sales<BR>www.Erwinspiano.com</FONT></DIV></BLOCKQUOTE></BODY></HTML>