>snip.... Given a panel crowned assembly with a severely dried >panel, and one rib crowned with a non dried panel, both to identical crowns >at room EMC, the one with the higher panel compression level will have the >steeper spring rate gradient, and will be stiffer. > > >Now correct me if I am wrong.. but I understand this to mean that a CC >board will be stiffer, both unstrung... and increasingly so when >downbearing is applied. Wrong. As we've discussed specifically and often, the RC board can be made much stiffer, both unstrung and strung, though the CC board will often have a steeper spring rate progression under deflection, at least while the crown lasts. >Assuming that is correct, and putting aside all other compression damage >discussion for a second or two... I have a question about this long term >so called compression set. It's not so called. It is a real thing, backed by that real science that you so often peripherally refer to lately. See "Understanding Wood" by R. Bruce Hoadley, for a start. Reading up on some of that real science you recommend will answer your questions. >On the side of this... and please forgive whatever lack of knowledge I >display in the asking, if compression from ribs being glued cross grain >to the panel is such a problem...even in RB boards.. is there no way of >contriving a rib such that it is a bit less constraining ? > >Just musing again > >RicB Yes, if you design the ribs to support the crown without needing panel compression to do so, and don't dry the panel to extremes, panel compression is no longer a problem. This should start sounding familiar about any time now. Ron N
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