Killer Octave Question

[Delwin D. Fandrich]

----- Original Message -----
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, April 11, 2003 7:15 AM
Subject: Re: Killer Octave Question


>
> >Del or you or someone also wrote a while back some examples of how much a
> >rim might commonly move by every-day events - like someone leaning
against
> >it, or the size change caused by a humidity change. As I recall these
> >movements easily were greater than the change in rib length between
curved
> >and straight. Any recollection of this?
>
> Yes, but not the numbers. Anyone who's interested can take some
> measurements of their own in a piano they have the soundboard out of and
> see what kind of pressure it takes to deform a rim 0.008", or a belly rail
> 0.0004".

Actually, my Journal article "A Guide to Soundboard Cracks & Other
Maladies--Part I" (The Piano Technician's Journal, December 1997) had both a
drawing and numbers.

I might add that you are being very generous with your numbers. I doubt many
compression-crowned soundboards have anywhere close to a 40' radius on
intallation.

Del