Soundboardcrown

[Phillip Ford]

> 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.

> 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



Phillip Ford
Piano Service & Restoration
1777 Yosemite Ave - 215
San Francisco, CA  94124