>Reverse crown occurs when the board shrinks enough for it to be >pushed to far or when a section of the rasten (where the board is >attached to the piano structure) has moved. On grands the belly >rail is the weak point and on others the long side is too >flexible. Beg to disagree here sir. Case, rim, rasten, or belly rail movement have little or nothing to do with crown retention or loss. The crown is initially formed, and maintained (or not) solely by the ribs. A new ribbed soundboard has plenty of crown long before it' ever glued into the piano. >These condition cause a "rolled bridge" but is really a >flattening of the board because of the movement of other case >parts. In other words bridges do not roll but soundboards go flat. Yes! >If a large section of the board is not glued well to the rasten you >could loose crown. Disagree, but it's not exactly a desirable condition anyway. >Best fix is likely springs between back post and rib to push it >back into place. Otherwise a new board with corrected case >structure. > > Newton Ron N
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