---------------------- multipart/alternative attachment . Isaac writes .I have yet a few questions about the > > geometry of down bearing , possibly when the rear slant is pronounced, > and that the apparent bearing as seen with a thread is very high (8 or > 10 mm for instance). > Stephen tells me it does not show the real pressure, as much of it is > "absorbed" by the slant in the bridge (between the pins). ....>>>It can be difficult to tell but I find working with the Lowell bubble down bearing gauge can give what I believe is a good indication of the bearing. > > I am still not sure to be clear on that. > > in that case, the real pressure may be showed by the rear bearing plus > the front bearing, and the eventual 1 or 2 mm slant on the bridge is > not to be considered in the computation (with the thread simple method > as used by most of rebuilders there). > > About the rib crowned soundboard, my idea was that they need a large > bearing in fact because this is installing internal tension on a panel > that is more neutral to begin with. >>>Yes but remember even a soundboard panel dried to 6% E.M.C. is still very dry and there is internal tension as it climbs to 12% or more . Also the addition of downbearing also creates tension but the total internal conpression it's not as severe or consequently destructive to the wood fibers As a purely Compression crowned board. So the bearing I apply although generous has its limits. It's a delicate & meticulous procedure. > If a CC crowned design where retained, adding pressure on it lessen > the internal tension, or leave it alone may be (because it goes the > same direction that the ribs trying to be flat (?????) >. Again push on it. Check the panel thickness. Is it thin..300/ 7.5mm uniformly or is it thicker .340 / 9mm or more. What dimesions are the ribs? All these thing have a consideration Best--Dale Erwin > > Best regards take care with that sun !. > > Isaac > ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/caut.php/attachments/71/a1/b0/69/attachment.htm ---------------------- multipart/alternative attachment--
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