Delwin D Fandrich wrote: > ----- Original Message ----- > From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> > To: "Pianotech" <pianotech@ptg.org> > Sent: August 29, 2003 11:40 AM > Subject: Re: Compression Question > > > > > > > John Patton wrote me a year or so back when I asked him about this and > said > > then that Steinway dries their boards down to about 4% and uses machine > > crowned ribs. FWIW. > > That is, then, a change from their traditional "perfected" practice. > > > > > Do I understand correctly that the rib crowned board will sooner or later > also > > surcomb to more or less the same self destruction, but that essentially > it will > > just take much more time for it all to happen ? > > Sigh. It depends on the MC of the soundboard panel at the time it is > ribbed. If it is 4%, yes, the panel will still self-destruct even if the > ribs are crowned. But the system will still retain most of the crown that > was machined (or otherwise put) into the ribs. If the MC of the panel was > up around 6.5% or 7% when it is ribbed it will still be possible to damage > the board by leaving the piano in a semi-truck trailer somewhere in > Tennessee during a summer heat wave for two weeks (every day well above > 100º F) while the driver goes on vacation but it is far less likely that > the panel will be damaged during anything resembling normal climate > conditions. > > Never is a long time and even wood beams stressed in thier longitudinal > direction will undergo some creep or compression set. At least in theory. > But, assuming a normal string load, after some initial settling it will not > be all that noticable over the lifespan of the piano or its owner. > > Del > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives -- 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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