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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=Richard.Brekne@grieg.uib.no
href="mailto:Richard.Brekne@grieg.uib.no">Richard Brekne</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> November 25, 2002 2:19 =
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Soundboard tension =
&
compression</DIV>
<DIV><BR></DIV><FONT color=#000099></FONT> <FONT =
color=#000099></FONT>
<P><FONT face="Comic Sans MS" color=#000080></FONT><BR><FONT
color=#990000>Richard Brekne writes:</FONT><FONT =
color=#990000></FONT>
<P><FONT color=#990000>And I just KNEW this was exactly where things =
were
going to happen. I guess thats a positive sign anyways.. :) It seems =
obvious
that all the confusion, or dissagreement, or whatever it is, is =
centered right
at this exact bit here... the presumed tension in the outside of the =
panel.
The confusion starts exactly the moment we release the assembly from =
the caul
then. Until that point, everyone seems to be in aggreement that there =
in
tension in ribs (panel side) and outside of the panel itself, and =
compression
on the inside of the panel. </FONT><FONT color=#990000></FONT>
<P><FONT color=#990000>What is not clear is WHY, (i.e. what the =
mechanisim is
and how it works) the tension in the ouside of the panel somehow =
reverses to compression when the panel is released from the caul. One =
is quite
liable to think that whatever tension was there would simply be halved =
(assuming the assembly returns aproximately half way to its origional =
flat
state). Actually, one could be tempted to think that this was the =
whole point
of the process... to pre-tense as it were, the outside of the panel so =
it
could take on crown without so much compression. And if one DID =
assume
that, then the rest of the logic that follows would seem to make =
perfect
sense.</FONT><FONT color=#990000></FONT> </P></BLOCKQUOTE>
<P dir=ltr><FONT color=#000080>Well, Richard, it may not be clear to =
you but it
is to many, if not most others. I should hope very few would actually =
tempted to
believe that whatever exceedingly slight tension the top of the panel =
started
out with would simply be halved. You're off considerably on the scale of =
the
various movements involved. There must be compression -- quite a lot of =
it -- to
hold the ribs in a crowned condition.</FONT>
<P dir=ltr><FONT color=#000080>I keep telling you that it would do =
you some good
for you to devise little experiments to illustrate these things but you =
seem
some averse to this approach. So, I've done it for you. But the file is =
some 3.5
or MB large (there are a couple of pictures). If you're interested I'll =
send it
on. </FONT>
<P dir=ltr><FONT color=#000080>Regards,</FONT>
<P dir=ltr><FONT color=#000080>Del</FONT></P></BODY></HTML>