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<p>Delwin D Fandrich wrote:
<blockquote TYPE=CITE>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080">I
do not know of any way to predict the panel stiffness of a compression-crowned
soundboard system. Even if a formula were developed I suspect the many
variables would degrade accuracy to the point of uselessness.</font></font></div>
</blockquote>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt">Well... obviously
you must have some way of finding the overall stiffness of the CC board...
or you couldnt know an RC board could be made stiffer at all.. let alone
for any particular comparisons sake. </div>
<blockquote TYPE=CITE>
<blockquote TYPE="CITE">
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt">So.. what.... the
ribs function in a CC board is primarilly to force the panel into compression
?? Why the choice of fat and not so high instead of lots of height... or
something else... what determines your choice of rib dimensions in a CC
board ?</div>
</blockquote>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080">THE
RIBS IN A COMPRESSION-CROWNED SOUNDBOARD SYSTEM HAVE TO BE FLEXIBLE ENOUGH
TO BEND IN RESPONSE TO THE STRESS INTERFACE BUILT UP BETWEEN THE EXPANDING
SOUNDBOARD PANEL AND THE RIBS. THIS IS HOW CROWN IS FORMED IN THE COMPRESSION-CROWNED
SOUNDBOARD SYSTEM.</font></font></div>
<br> </blockquote>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt">Well shoot there Del..
I knew that already... was just wondering if that was all of it... whether
or not there was something a bit more specific.</div>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080"></font></font></div>
<p class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080">If
the ribs are too stiff there will be little or no crown. The wood fibers
will still compress as they take on moisture but they won't be able to
develop enough force to create a crown in the system -- the wood's perpendicular-to-grain
compression strength limit will be exceeded before crown is developed.
Selecting the right rib cross-section was probably an empirical study in
cause and effect.</font></font>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000000"></font></font></div>
<p class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000000">trial
and error you say ? hmmmm.</font></font>
<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080"></font></font></div>
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<div class="MsoBodyText" style="MARGIN: 0in 0in 0pt"><font face="Comic Sans MS"><font color="#000080">Del</font></font></div>
</blockquote>
<p><br>Ok... dont want to try your patience. A little at a time I get these
peices to fit. Still lots of unanswered questions.. but one thing at a
time.
<p>Thanks muchly Del.
<p>--
<br>Richard Brekne
<br>RPT, N.P.T.F.
<br>UiB, Bergen, Norway
<br><A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A>
<br><A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A>
<br><A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>
<br>
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