Hi Ric, > To the direct claim that stiffness (in any direction) does not increase > with compression. This is simply false. It does. Wood is usually sorted > into grades that are related to density, straightness of grain, grain > consistancy... etc. Looking at the tables in just about any such manual > one sees quickly that E, and for that matter just about all strength > properties, increase as density increases. Since a compressed panel is > essentialy a more dense panel then it would be without the compression, it > goes without saying that it becomes stiffer. Thus my caveat about the SB components *not* being ideal springs. I just didn't know *how* non-ideal! It would appear the material is highly nonlinear, which could account for some of its unique acoustic properties. Strange stuph, wood... ;-) It seems to me that a completely *uncompressed* RC/S panel would have to be made thusly... (1) Determine the total desired downbearing of the strings. (2) Determine the initial curvature of the ribs needed to support said downbearing with the desired final crown (which would be flatter than the initial, unloaded curvature). (3) Stabilize the panel wood at the target ambient RH (e.g. 42% RH). (4) Glue up the ribs under load, with the curvature of the setting/drying/curing assembly being the same as that of the final assembly under load. (Do this preferably with epoxy.) When released, the panel would spring back somewhat, putting tension, not compression, on the panel. But when the panel is mounted into the rim and placed under load, the panel tension would be relieved, and the net tension/compression on the panel would be zero. Is this how it is done??? Peace, Sarah
This PTG archive page provided courtesy of Moy Piano Service, LLC