Buttressed Arch. Question for Ron N.

[david at davidandersenpianos.com]

Wow.  I just saw it, got it, grokked it.  Thanks, brother. Sincerely.

David A.
>
> 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
>