<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF"> Delwin D Fandrich wrote:   <blockquote TYPE=CITE>           Richard Brekne writes: <blockquote dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000080 2px solid; MARGIN-RIGHT: 0px">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. 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.</blockquote> <div dir="ltr">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.</div>  </blockquote> Well, gotta admit Del, the halved thing just came straight from an assumption from this text of Junnhann, which evidently is not held in much esteem by any of the contemporary designers. But then I should think that many would actually draw this conclusion without knowing more about the subject. You say yourself how many tears you have shed over the level of knowledge folks have coming out of woodworking schools. And you mention your own experiences with many others getting confused on exactly this point. But, you've got me finnally jagged on reading up on this subject matter too, so as I said in my last post I have my Christmas reading cut out for me.   <blockquote TYPE=CITE> <div dir="ltr">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.</div>  </blockquote> No nono... I'm not adverse to it at all... just so many hours in a day as I am sure you know, and I simply have to spend at least a couple in the evening relaxing in front of my puter... and believe me it has done me tons of good reading and corresponding with you all these past years... tho to be sure much remains (and always will) to be learned. I would love the file and appreciate your efforts more then perhaps I am able to convey. And, now that I have gotten a few "biggies"  on my personal goals list out of the way this past couple years,  I certainly promise to carry out a few experiments in wood working this comming year. I have DSL lines so  3.5 MB is not a problem. <blockquote TYPE=CITE>  <div dir="ltr">Regards,</div> Del</blockquote> 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>   </body> </html>