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<p>Ron Nossaman wrote:
<blockquote TYPE=CITE>>snip.... Given a panel crowned assembly with a severely
dried
<br>>panel, and one rib crowned with a non dried panel, both to identical
crowns
<br>>at room EMC, the one with the higher panel compression level will
have the
<br>>steeper spring rate gradient, and will be stiffer.
<br>>
<br>>
<br>>Now correct me if I am wrong.. but I understand this to mean that
a CC
<br>>board will be stiffer, both unstrung... and increasingly so when
<br>>downbearing is applied.
<p>Wrong. As we've discussed specifically and often, the RC board can be
made
<br>much stiffer, both unstrung and strung, though the CC board will often
have
<br>a steeper spring rate progression under deflection, at least while
the
<br>crown lasts.
<br> </blockquote>
Well.. you'll excuse me if I find this directly above in direct conflict
with
<blockquote>"the one with the higher panel compression level will have
the steeper spring rate gradient, and will be stiffer."</blockquote>
and please remember the qualifiers for this example so as to keep it in
context.... it was equal crown at same RH, and further we were to
leave all other compression damage issues aside for a moment.
<br>
<blockquote TYPE=CITE>
<br>>Assuming that is correct, and putting aside all other compression
damage
<br>>discussion for a second or two... I have a question about this long
term
<br>>so called compression set.
<p>It's not so called. It is a real thing, backed by that real science
that
<br>you so often peripherally refer to lately. See "Understanding Wood"
by R.
<br>Bruce Hoadley, for a start. Reading up on some of that real science
you
<br>recommend will answer your questions.</blockquote>
Real science Ron... means also answering a question in the context it was
given with qualifiers intact... and do me a favour... dispence with the
scolding routine. And FWIW the term "so-called" isnt a derogatory.
<blockquote TYPE=CITE>
<br>>On the side of this... and please forgive whatever lack of knowledge
I
<br>>display in the asking, if compression from ribs being glued
cross grain
<br>>to the panel is such a problem...even in RB boards.. is there no way
of
<br>>contriving a rib such that it is a bit less constraining ?
<br>>
<br>>Just musing again
<br>>
<br>>RicB
<p>Yes, if you design the ribs to support the crown without needing panel
<br>compression to do so, and don't dry the panel to extremes, panel
<br>compression is no longer a problem. This should start sounding familiar
<br>about any time now.</blockquote>
Again.. thats not the question I asked.... Or perhaps you are saying that
under no circumstances can the constraint placed by the ribs on the panel
cause problems regardless of climatic conditions ? I asked if there was
a way of contriving a rib such that it was a bit less constraining to the
panel ... as in either compression or tension.
<blockquote TYPE=CITE>
<br>Ron N
<br> </blockquote>
<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>
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