Unusual rib structure?

[Farrell]

FWIW - I've noticed on many boards that even when positive crown is present, there often will be an inch-or-two wide swath of negative crown adjacent to the rim. I guess from the ribs being thin there. I wonder what, if any, consequences there may be to this.

Terry Farrell
  
----- Original Message ----- 
From: "Ron Nossaman" <RNossaman@cox.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: Wednesday, May 07, 2003 11:47 PM
Subject: Re: Unusual rib structure?


> 
> > > That's why I asked. Everyone wants to measure crown in the place where
> > > soundboards nearly never go concave, and never the place where they nearly
> > > always do. How does it look in octave 6, where crown typically reverses?
> >
> >Ah!  I didn't know that.  Well, I placed a straight edge up under the
> >soundboard close to the second treble rib.  My guess (since I can't really
> >measure very well there) is that I have slightly less than 1/8" of crown
> >there.
> 
> Very surprising.
> 
> 
> >Most of the curvature seems to be where the rib tapers, if that
> >means anything.
> 
> Means it's a compression crowned board.
> 
> 
> >The middle of the high treble board is less curved, with
> >perhaps 1/32" of arch to it, depending on where the starting and stopping
> >points are defined.  So is it a keeper? ;-)
> 
> It might very well be a miracle!
> 
> Ron N
> 
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