Soundboard drydown for installation

[Farrell]

I think this goes back to traditional engineering arch theory. If you dry 
the board down, it will have a slightly smaller footprint - the ribs will 
shrink a teeny-weeny bit and at least the top of the panel will shrink. Then 
if you glue the dried board into a tightly fitting case, when the board 
takes on moisture and crown develops, the crown will be enhanced because now 
the board can't expand that little bit (the rib lengths and the top of the 
panel). So now the case is supporting the crown and the ribs are an arch.

'Course, none of this actually works - the ribs won't shrink much, the panel 
top edge will just crush when it expands the 1/10 mm that it might move and 
the rim has enough flex to negate any "arch" support.

But I think the first paragraph above is pretty much the reason the practice 
persists. And in any case, even if it doesn't have any significant effect, 
some minimal drying prior to installation is likely to make most any 
rebuilder sleep better at night because s/he hasn't offended the Goddess of 
the piano soul.

Terry Farrell

----- Original Message ----- 
> Too bad there is a lack of response on this thread Mike.  Seems a good 
> question that more then a few would benefit from some good 
> answers/thoughts.
> Cheers
> RicB
>
>
>        Richard, I'm glad you asked that.  I too wonder why.  Once the
>        ribs are
>        on, I can't rationalize a benefit to taking the board outside of
>        the
>        normal range of (controlled) workshop humidity for installation
>        in the
>        piano.  Not that I would be surprised to learn of several good
>        reasons
>        for doing so.  I hope you get some interesting answers.
>
>        Mike