---------------------- multipart/alternative attachment Delwin D Fandrich wrote: > > 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. > 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. >> 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 ? >> > 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. > > 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. 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. trial and error you say ? hmmmm. > Del > 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. Thanks muchly Del. -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/ff/fd/60/a3/attachment.htm ---------------------- multipart/alternative attachment--
This PTG archive page provided courtesy of Moy Piano Service, LLC