Ric/JD Even if a compression Crowned board could bend those short treble ribs into a 60 ft radius it would be negligibly measurable. SO 25 % of residual crown of that is almost zip. Del & others have made the case that the upper treble area is driven primarily by mass & stiffness due to the smaller board area & stiff ribs... I agree. I crown these ribs as tight as 15 ft but even so on a 15 inch rib were only talking scant MM or 2. But I like having something to push against that resembles real crown. Makes sense? Dale Hi JD Your understanding of the RC & S board seems pretty solid to me. One point I'm less sure on is the amount of compression in the panel after the strings are on. The ribs are more solid as you say... and short ribs with tight radii are not all that easy to bend. Yet there is a stated goal of applying enough downbearing so that 25 % of the unloaded crown remains after stringing. That strikes me as equating to a good deal of compression in the panel. Looking around these past few days and asking questions in a variety of places... I'm left wondering if there IS any direct way of figuring just how much compression a given lateral load on a beam will build up in the panel. Perhaps its a matter of looking around long enough... perhaps it just hasn't been considered directly much for the same reasons that tension along the grain of beams doesn't seem to attract too much attention in wood engineering texts. **************Start the year off right. Easy ways to stay in shape. http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489 -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20080127/1decb696/attachment.html
This PTG archive page provided courtesy of Moy Piano Service, LLC