Hello Ron N & all, >>What RH do you glue the ribs to the soundboard at? I assume >>anything lower than ambient RH would induce some compression >>crowning (once the piano was exposed to something higher, say, >>summer's humidity -- today the RH is frightfully low) -- but I >>freely admit that's just a gut reaction, not a calculation. >> >>Patrick > > >In the neighborhood of 6%-6.5%. Yes, there will be some compression >crowning, but not much, and I expect it to be pretty much >non-existent in a few months under string bearing. Seasonal swings >will always change compression levels in panels no matter how the >soundboard is built. My point is that I'm not counting on the panel >to support crown either initially, or in the long run. The ribs are >dimensioned to do that. The panel provides stiffness along the grain >and rides along with the ribs to move air. > >Ron N Similarly, we dry a solid panel down to 6.5%, and yes Patrick, a very small additional crowning results once the panel normalises. When we use a laminated panel, it is dried after gluing the layers, then allowed to stand and normalise before gluing the ribs. Ron O. -- OVERS PIANOS - SYDNEY Grand Piano Manufacturers _______________________ Web http://overspianos.com.au mailto:ron@overspianos.com.au _______________________
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