Delwin D Fandrich wrote: > ............ > To better visualize what the rib is actually wanting to do all this time, > go back to that little experiment I described and carefully remove the > cross-grain portion of your sandwich. What happens to the longitudinal > piece, i.e., the rib? It does exactly what it has wanted to do all along -- > it returns to it's rest (or flat) configuration, doesn't it? Now, what on > earth makes you think it wasn't wanting to do that all the time? Why would > the wood fibers suddenly lose their memory just because they get pulled out > of equilibrium by the expanding cross-grain panel and the resulting > stress-interface? Wood technology doesn't change just because some of us > don't want to acknowledge its rules. For the time your sandwich was being > held in a crown by the stress-interface between the longitudinal rib and > the cross-grain top piece do you suppose it somehow -- miraculously -- lost > its desire to get itself straightened out? I can't conceive how. That bent > rib is a spring, what are its lines of force? > Hmm... Like I say.. the only thing I dont understand is what happened to that tensioning (pure stretching) force on the rib.? I mean.. the rib forces the panel to compress, and the flip side of that coin is that the panel is at least going to attempt to force the rib to lengthen. The degree it fails in doing so results in the bending of the rib and the formation of crown.. yes ?? But what about the degree it succeeds (if any) ? If the rib is at all tensioned in the sense that it is lengthened in addition to the tensioning that occurs in the top half from bending... then I dont see how the rib could not be supporting crown, because if thats the case there is more going on then just the ribs desire to straighten out.... It also has a desire to not tension any more, which downbearing on the panel will tend to do. > Ponder this stuff as you will, I'll get excited when I see how these > hypothetical questions actually provide meaningful information that will > help me design a better sounding soundboard system and a better sounding > piano. Right now, however, I can't conceive how they will. > Grin.. well hell Del... you misunderstand me here.... I am not trying to tell you or anyone how soundboards function or not... I am simply asking questions because there are things I dont understand. That I dont take it for granted that any other particular person fully understands things either is only a healthy insurance policy to keep me on a learning track. While I realize that can be bothersom to some few, it is my experience that the great teachers of the world have enough patience to cover this bothersomness to begin with, and enough humility to remember that no matter how much they know... one never knows when something is been overlooked or missed. ... heck... thats the whole spirit behind our prime directive here... "there's no such thing as a dumb question" You no doubt build fine pianos and anyone should be proud to be able to achieve the same level of expertise. You mustnt ever think I believe anything else. Tho I respect your professional contributions beyond what I am able to express here, I do not do so blindly. That would be foolish of me.. yes ? > Del > Cheers RicB -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html
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