This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment Terry Farrell said: " When flat ribs are glued to a very dry flat panel, no force vectors exist in the system. As the panel takes on moisture and the ribs bend, the ribs will always be trying to pull the panel flat. Period. If that assembly has crown, the ribs will always try to go straight by pulling down on the panel. The compression forces in the panel are the only thing that has provided the force necessary to bend the rib into a crown. Whether or not you ever load that soundboard on top, the ribs will always be fighting the panel compression to go flat. When you do apply a load to the top of the soundboard, the compression on the panel will increase, but the ribs will do nothing other than still try to go flat. As the crown lessens under increasing load, the ribs will pull downward a bit less, but only because they are being bent upwards less by the panel. " The way I see it, the reason why we have the killer octave problem with mostly CC boards, is that the crown produced with the panel's growth will be kind of proportional to the lenght of the ribs. So, with this method the treble that always have shorter ribs than the tenor will have less crown in the beginning. Since compression will affect the board's with aging, we end up with a dead killer octave and a no crown zone exactly where the ribs get shorter...in the killer octave. So I guess there is no way to have a decent board assembly that will have a predictable lifespan with the Compression Crowned method. It's physics. Again, I might be wrong, but I think I've seen the light. Marcel Carey, RPT Sherbrooke, QC ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/a8/0d/5a/54/attachment.htm ---------------------- multipart/alternative attachment--
This PTG archive page provided courtesy of Moy Piano Service, LLC