I see you are two steps ahead of me in one direction here Ron. And of course I agree that I have seen this in pianos, and thats half of why I asked. The other half is that I'm still trying to get ahold of exactly how this shrinking and expanding works.... especially in the face of a compressioned peice of wood. Something about the fact that a panel having assumed a certain set of dimensions at a given EMC tells me that it shouldnt be able to get smaller then those same dimensions at that same EMC. Ok... so compressing the panel as described doesnt stop a panel from shrinking as its moisture content drops... tho it does to some degree inhibit that shrinking capacity. I suppose this means that the cells would be even tighter pulled together as origionally they were when first dried out to the same EMC. I guess its this last that causes my present head scratching. RicB Ron Nossaman wrote: > >If you take an unribbed panel, and dry it out to the extremes of 4% MC, > >and then constrain its dimensions at that so that it is not allowed to > >expand either outwards, or upwards or in any fashion and bring the MC up > >to 13 % the panel will get pretty severely compressed... yes ?... ok.. > >If you allow this to sit over enough time that if in releasing the > >constraints the panel simply retains the dimensions it had under > >constrainment.... then what happens to the size of this panel if you > >dry it down to 4 % again ? > > You've seen the answer to this question in a lot of pianos. It will shrink, > but not nearly as much as an un-crushed panel would. If the panel didn't > still shrink after being crushed and damaged by restraint under expansion, > it wouldn't ever crack. > > Ron N > > _______________________________________________ > 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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