rim supported soundboards tesnion resonator rods

[Delwin D Fandrich]

----- Original Message -----
From: "Richard Moody" <remoody@midstatesd.net>
To: "piano tech" <pianotech@ptg.org>
Sent: February 05, 2001 10:42 PM
Subject: rim supported soundboards tension resonator rods


> There is nothing preventing piano makers from using the rim to support a
crown.

Only the physical characteristics of the wood itself. This is another
subject I've dealt with in my Journal articles -- refer to them for the
math. The rim could, indeed, be used to both form and support soundboard
crown if the material used to make up the soundboard were a completely rigid
material. Brick, stone and mortar come to mind, but wood?, no.



> Whether it worked or not is another story.

It didn't.



> Yet according to Dolge, the "Tension
> Resonator" patents of Richard Gerz in 1900 were supposed to do just that.

This isn't the first patent that didn't work as envisioned.



>     I have heard considerable debate about what actually (if anything) was
> accomplished by the rods.

The do add considerable stiffness to the rim -- not that the M&H rims need
much help along those lines.



> Never the less if M&H did design a rim to support the
> sound board arch the concept was at least given a try. The interesting
part of
> the debate to me is whether this is an efficacious way of maintaining the
crown.
> I am not sure anyone knows, unless they are/have actually used it.

It's easy enough to test. Make a test fixture emulating the grand rim and
check it out. You'll not be the first to have done so.



>     I wonder if makers have put soundboards by themselves in a room with
> variable humidity and measured dimensional changes, the arch in
> particular.  ---ric

Yes.

Del