---------------------- multipart/alternative attachment Ron, Would you care to describe your method of rib crowning a board for me? Also could you suggest some reading I could do on the subject? (I don't have the Journal index on CD) I'm curious to know what I'll be needing. Since I'm heading to a woodworker show this weekend it might be a good idea to have an idea of what faces me in the weeks ahead. THANKS!!! Greg Ron Nossaman wrote: > > On a five-foot span I get 0.63 inches of crown. > >This seems excessive (isn't an unstressed new board supposed to have about > >1/4" - 3/8" of crown in the middle?). > > Your crown height for 60' radius is right by my figures, but how long a rib > do you plan on having in a piano? That's what cutoff bars are for. The > compression crowned boards ended up averaging about XX crown at XX length > (varying widely with material choice and methods) as a consequence of the > crowning process rather than a design criteria. With rib crowning, you are > granted the opportunity to make your own decision and build to a much > closer spec. It's supposed to be whatever you find works to your > satisfaction with all the other dozens of factors considered in your > soundboard design, string scaling, bridge configuration, loading, etc. Nor > is it particularly necessary or (to some builders) desirable to have the > same crown radius throughout the rib scale. > > >Or is it that on the rib-crowned > >board, you cut the rib to the aforementioned arc, glue it to the board in a > >caul of the same arc, and when removed from the caul the naturally flat > >board help the assembly to straighten out a bit to where it has the > >"?normal?" 1/4" - 3/8" of crown? > > Panels are still dried down before assembly in a rib crowned board, just > not as much as with compression crowning, so the panel is still under some > compression, and still helps support crown rather than dragging it back down. > > >Am I making a boo-boo somehow with my drawing? > > > >Terry Farrell > > Nope, but there are a few assumptions behind it that you need to decide > whether or not to accept. <G> > > Ron N -- Greg Newell mailto:gnewell@ameritech.net ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/66/16/3f/58/attachment.htm ---------------------- multipart/alternative attachment--
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