Guys, it hasn't changed since last time. Referring to old cracked compression crowned soundboards: A soundboard isn't in any way the surface of a balloon. The compression in the panel bends the ribs and forms the crown. The same compression also causes compression ridges as the structural limits of the panel are exceeded. Cracks are past compression damage. Shims are put into cracks, which are the most compression damaged part of the panel. Flat and negatively crowned soundboards are cumulative compression damage of the entire panel. Rims are not arch buttresses, and do not form or maintain soundboard crown. Read Del's articles. Read the extensive and voluminously detailed discussions of just these things in the archives. Ron N
This PTG archive page provided courtesy of Moy Piano Service, LLC