<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF">   <p>Delwin D Fandrich wrote: <blockquote TYPE=CITE> <blockquote dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800080 2px solid; MARGIN-RIGHT: 0px">4 The<font color="#000000"> across grain compression strength  </font>that maintains crown in compression crowned boards is inherently weak and will dissipate over time. (relatively short ??) (regardless of such factors like such as climate ??)</blockquote> <div dir="ltr"><font color="#800080"><font size=-1>Yes. It is both time and stress dependent. The more compression stress the wood fibers are under, the faster the resulting compression-set will occur. The longer the wood fibers are under compression, the more they will be permanently deformed.</font></font></div> <div dir="ltr"><font color="#800080"><font size=-1>This is climate dependent to the degree that during dry periods moisture will be drawn from the wood fibers and the panel's internal compression will decrease. During humid periods the wood fibers will absorb moisture, try to swell, and the panel's internal compression will increase.</font></font></div> <br> </blockquote> <div dir="ltr">Does this mean that the a compression soundboard assembly can hold crown as  long as RH is held at high enough levels to sustain internal compression ? Or do you mean to say that the assembly fail anyways...perhaps more slowly. ?</div> <blockquote TYPE=CITE> <blockquote dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #800080 2px solid; MARGIN-RIGHT: 0px">I am not quite sure why a compression board is said to be "damaged" (fiber compression damage) when in essence this damage is meaningless in as much as all one has to do is re-rib and reconfigure for a rib crowned assembly.</blockquote> </blockquote> <p><br>As you and Ron both make the same very valid points here, I dont need to go further then to say that that subject matter, important as it is in itself is another matter. Certainly in that perspective the assembly failing due this kind of damage has meaning..and lots of it... no one is going to argue that point me thinks.. <br>  <p>One other thing... you mentioned somewhere along the line I believe,  and I think Ron has echoed this in another thread a while back... that in a best case scenario for a compression board... the sound can be in some sense better or more powerfull... or something of this nature then in a non compression board..... but that that is of little use because it is so short lived amoung other reasons... or have I mis-understood you here.? <br>  <br>  <p>-- <br>Richard Brekne <br>RPT, N.P.T.F. <br>Bergen, Norway <br><A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <br>  </body> </html>