---------------------- multipart/alternative attachment In a message dated 10/25/02 9:20:05 AM Central Daylight Time, mfarrel2@tampabay.rr.com writes: > > Conventional wisdom suggests quarter-sawn spruce for soundboard panels. > Quarter-sawn will mean different things to different folks, ranging > anywhere from 45 to 90 degrees to the plane of the panel. What is the > recommended range of tolerance (how much deviation from perpendicular is > acceptable)? Even in high quality instruments I see up to about 45 degrees > (most is better, but I do see this much deviation). > > And perhaps more importantly, WHY? What difference does it make? Why might > it make a difference? Is it because the panel will lay better? Because it > looks better? Is it just so one manufacturer can claim "ours is better than > theirs"? Because sound can "reflect" through some angles better than others > - maybe a 45 degree grain angle refracts all the sound into outer space? > What is the current wisdom? What are the current thoughts? What is the > current hearsay? What is the current misinformation? What are the current > rumors? Thanks. > > Terry Farrell > > Terry though I have never heard a scientific answer I have theory. The angle in the grain causes shear forces in the soft grain under compression, the more angle the more shear force. It takes less shear force to cause failure than straight compression force. With true 0 degree quarter sawn lumber the wood compresses in a parallel manor 90 degrees to the surface. In a board with an angle to the grain one layer of soft grain can have a tendency to ride up on the hard layer using it as a sort of ramp (if you can picture that) therefore creating shear forces. Sometimes you can actually see an old soundboard with compression ridges where the grain has shifted, it is a staircase effect. Many old Mason Hamlins have this problem. OK, that is my theory and I am ready for the experts to set me straight!!! David Koelzer Vintage Pianos DFW ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/d7/62/c8/6f/attachment.htm ---------------------- multipart/alternative attachment--
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