> I don't KNOW, Ron. But if you keep talking I'll shut up and listen. If my > brain were as flexible as Sitka, I'd be fine. > Thanks, > Fenton When you bend a piece of wood (rib), the fibers on the convex outside of the bend are stretched, and the fibers on the concave inside of the bend are compressed. So if you glue an expanding panel on one side of that piece of wood (rib), it will stretch the rib's fibers at the glue joint as it expands, bending the rib. Bending the rib stretches the fibers on the outside of the curve (top), and stretching the fibers on the top face of the rib causes the rib to bend and increase crown. It's that simple, and has not a thing to do with an arch. The panel will still rise and fall with humidity swings because the compression level in the panel changes with it's moisture content, and the resulting degree to which it stretches the top side of the rib changes with it, changing the crown rise as a result. Still no arch involved, it's a self contained leverage that works without end buttresses. Better? Ron N
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