>I didn't think that wood expanded and contracted very much along the >rain and that crowning took place due to the dimensional changes across >the grain. >David Love >davidlovepianos@comcast.net Hi there David Crowning perse... has nothing to do with dimensional changes across the grain.. or in any direction for that matter. Rib crowned boards are ... shall we say... pre-crowned in that context. Anytime you force a curvature into the panel you <<crown>> it. We can have negative or positive <<crown>>, we can have so called natural crown or crown induced by forcing the panel onto curved ribs. Or.. you can just plane bend the entire panel as part of glueing it into the rim. This last is what I understood Udo to be saying relative to long the grain crown. Seems like some soundboard installation proceedures stress the panel in this sense as part of attaching it to the rim, or as part of how they crown the panel to begin with. In anycase, some piano manufactures end up with a panel that has both cross grain crown and crown along the grain. And the point at which these two crowns intersect is the highest point of the assembly. Thats my understanding of things anyways. Perhaps some of our German reading friends out there can translate a bit of this so called K-point from Fenners recent book. Cheers RicB
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