<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF">   Farrell wrote: <blockquote TYPE=CITE> Comments below - I need some clarification to address these issues.</blockquote> Rather then copy over all this let me just re-word and see if that helps. A crowned CC panel, in addition to whatever else it is... is a curved peice of wood. And as such the convex side will be stretched relative to the concave side.  The overall levels of compression in the panel make no difference in this regard. When downbearing is applied, then the convex side will be compressed, and the concave side will stretch relative to their condition before downbearing is applied. . But the ribs resist this stretching tendancy, they will resist any stretching tendancy on the part of the underside of the soundboard. In otherwords... the underside of the panel tried to expand when it took on humidity... the ribs resisted this and crown was induced and the ribs were bent. Pushing down on the board will increase the panels pressure on the ribs because the underside wants to expand even more.   <blockquote>So as stated above, when you apply downbearing, yes, the concave side of the rib stretches, but only with reference to its curved compressed state - it doesn't stretch relative to when it was straight. I think it is more appropriate and more clear to state that when downbearing is applied, the concave side of the rib experiences a reduction of its compressed state.</blockquote> Terry.. I think you misread something here out of what I was saying ...yes ??  Applying downbearing will stretch the concave side of the panel.. the convex side of the rib will see this tendancy to expand just as it sees any tendancy to expand on the part of the panels underside.... it will resist the expansion. Hence the rib will experience an increase in stress,... ergo it has to be supporting the crown against downbearing.  Just because the the rib is a bit flatter, and there is an apparent lessening of the compression in the lower half of the rib,  doesnt mean we can ignore this increase in stress on the rib as a whole... or what ? I dont see at this point how we can get around that, except by refuting that the underside of the panel will want to expand when down bearing is applied... and I dont see how we can get there at all. I hope I've made clear where I'm getting hung up accepting this "ribs dont support crown against downbearing" position. Cheers RicB -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>   </body> </html>