evaluating sdbd. crown & bridge downbearings in a new piano

Frank Weston klavier@annap.infi.net
Thu, 23 Sep 1999 17:06:20 -0400


Ron wrote:

>Think, and remember. No one has ever even hinted that the panel is equally
>compressed at the top and bottom. It has been stated a number of times that
>the panel is compressed more at the bottom than at the top, but the entire
>panel is, inescapably, compressed. There just isn't any way around it.


You are absolutely correct Ron ....... if you assume that the entire
soundboard assembly is constrained from expanding as it takes crown.  Such
is not the case.  If the assembly did not expand, then the ribs would be
under NO tension and would be incapable of opposing the load exerted by the
soundboard.  If the ribs are under tension, they stretch, ergo the assembly
does expand.  Whether the entire panel is compressed depends on the relative
sizes, geometry, and material properties of all components of the entire
assembly.

Frank Weston



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