Laminated Soundboard Ribs

[Delwin D Fandrich]

----- Original Message -----
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: <pianotech@ptg.org>
Sent: February 11, 2002 6:53 PM
Subject: Re: Laminated Soundboard Ribs


> I guess a lot of my thinking comes from laminating ribs on boat hulls. I
do realize that a soundboard is not a hull. And the laminated ribs on the
boat replace steam-bent oak ribs. The laminated ones are nice because they
tend to hold their shape way better than the steam bent ones. You may well
be right that laminated would not be any stiffer than a solid rib. Part of
my thinking is also that you need to saw through the grain to make a crowned
soundboard rib - but of course, you are only cutting into it 1/8-inch or so.
Some boats have sawn ribs and you end up with much of the wood grain not in
a preferred orientation.


Terry,
A laminated boat rib will be much stronger than a steam-bent rib because the
process of steaming and bending weakens the wood (usually white oak)
considerably. All things being equal a laminated spruce rib has about the
stiffness as a solid spruce rib of the same dimension and grain
characteristic. Keeping in mind, of course, that the stiffness
characteristic (i.e., the modulus of elasticity) given in reference books is
a number representing an average of many samples of widely varying grain
characteristics. A rib made of wide grain lumber will not be as stiff (or as
heavy) as a rib made of tight grain lumber.

Del