rib glueing

[Delwin D Fandrich]

----- Original Message -----
From: "Garold Beyer" <garbey@wingsisp.com>
To: <pianotech@ptg.org>
Sent: January 09, 2001 4:01 PM
Subject: Re: rib glueing


>
> >>If one is using
> > > straight ribs and compression crowning (I am), does pressing into a
> curved
> > > surface have any material effect on the crown or is Jack Krefting
> correct
> > > when he stated in one of his series of articles that it does not.
> >
> > Huh?  Of course it will have an effect on the resulting crown.
> > Del

The way I read the above, says:
    --    We're compression-crowning a soundboard panel. That normally
implies a soundboard panel dried to approximately 4.0% MC.
    --    If flat ribs are pressed onto this panel against a flat surface a
given amount of crown will result as the panel absorbs moisture and returns
to a normal (for the climate) MC.
    --    Given the same panel at 4.0% MC and the same flat ribs, but this
time glued up using a curved caul (surface), the finished soundboard
assembly will have the same crown when the assembly has reached the same
equilibrium MC in its normal climate.

I disagree. With all other factors being the same, the compression-crowned
soundboard panel glued up against a curved caul/surface will end up with
more crown than the one glued up against a flat caul/surface.

Del