Soundboardcrown

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip Ford" <fordpiano@earthlink.net>
To: "Pianotech" <pianotech@ptg.org>
Sent: December 18, 2002 10:30 AM
Subject: Re: Soundboardcrown


>
> > Ron N. wrote:
> >
> > > It would arc anyway because of the ribs,
> > regardless of whether or not it
> > > was glued to the rim. Are you intending the
> > rim to maintain the crown?
> >
>
> Terry Farrell wrote:
>
> > That's what I was getting at. It sounded to me
> > like he was expecting the board to expand, the
> > rim to stay put, and thus put the crown in the
> > board.
> > My understanding was that Peter glued the ribs
> > to the panel while all were EMCed at 60% RH.
> > The only reason there was a little bit of crown
> > in the board before putting into piano was
> > because he pressed the flat ribs into a caul
> > that bent under the air pressure. So I suppose
> > that would indeed put a little compression into
> > the board. But then he dried it way down and
> > glued it into the rim. I think he is under the
> > impression that drying down the ribbed board
> > and gluing it into the case is going to produce
> > a bunch of crown because the rim will be rigid
> > and support that crown.
>
> This was what I understood as well.

Hmmm. Well, if that is the theory -- it won't work.


>
> > Del wrote:
> >
> > > What Peter is doing is simply taking the
> > compression out of the panel
> > > temporarily, letting the assembly flatten
> > out, and then gluing it to the
> > > rim. As moisture goes back into the panel it
> > once again becomes a
> > > compression-crowned soundboard assembly.
>
> If the ribs are what is maintaining the crown and if you believe the rim
> contributes nothing to establishing or maintaining crown what is the point
of
> drying the board back down before gluing it to the rim?
>
> Phil F


I don't know.

Del