Del and all, >At 6:25 PM -0700 19/4/03, Delwin D. Fandrich wrote: >. . . Compression set is much more of a problem perpendicular to >grain than it is >parallel to grain. A compression load that will turn spruce to pulp when >applied across grain will barely faze the same piece of wood when applied >parallel to grain. > >Del Yes indeed. Now this leads me to wonder just how much longer we might expect a sound board with a properly laminated panel to last? I have yet to pull down a piano with such a board in it after many years of service, but I feel the laminated panel will be much more reliable than anything one could build in solid spruce. The problem with solid sound boards as I see it, is that the compression set will always tend to occur in the weakest sections of the boards. This explains why we see strips of the sound board panel which appear to be free of ridging, while other sections (often located towards to edges of the boards, and adjacent to the glue joints) will show obvious signs of compression set. A laminated panel, on the other hand, will tend to force to compressional load, on a sound board panel, to be more evenly distributed across it. This is, I believe, why laminated panels continue to retain (visually at least) an uncompressed surface as the piano ages. Our no. 003 piano is showing no signs of any ridging at this point in time. The panel in this piano is a standard Samick five ply 7.5 mm thick panel (all spruce). The new laminated panel which we are about to build for piano 6 will have three laminations only, a center lamination of 3.5 mm, with a top and bottom lamination of 2.25 mm each. This will allow us to sand off 0.5 during final finishing without going below 7.5 mm. Ron O. -- _______________________ OVERS PIANOS - SYDNEY Grand Piano Manufacturers Web: http://overspianos.com.au mailto:info@overspianos.com.au _______________________
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