Laminated ribs

[Delwin D Fandrich]

----- Original Message -----
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: August 17, 2003 4:04 PM
Subject: Re: Laminated ribs


>
> >          My question is are these flat laminated pieces cut with a
crown
> > in them or are you crowning the ribs  in a curved caul. I know this was
> > discussed some time back but hey I don't recall it. If they're
laminated
> > in a curve aren't they indeed more of a true arched rib (or arched
beam)
> > than a solid piece of  spruce rib stock with a machine cut curve. In
the
> > rib glued in a curve the ribs  the grain is indeed in an arch even if
it
> > was made thick enough to cut the bottom of the rib flat so as it had
more
> > material in the middle than on the ends. With a rib laminated in an
arch
> > config. it's also possible to have a rib of uniform dimension (if thats
> > desireable).
>
> Is a rib you make from a single piece of wood with curved grain an arch?
> The laminated rib isn't either because the laminations are glued
together.
> As long as the glue holds, it's a solid piece of wood.
>

Well, not quite. In a bent lamination the outside (convex) laminae are
under some amount of compression and the inside (concave) laminae are under
some amount of tension. How much depends on the material used, the radius,
the height of the bent lamination, etc. But that is what holds it in a
curve.

Del