evaluating sdbd. crown & bridge downbearings in a new piano

[Ron Nossaman]

>On the side of all this.. I have always wondered about something that perhaps
>some of you can answer for me. What is "wrong" with the idea of "heat
shaping" a
>board into crown. Much like boatmakers apply heat and humidity to bend planks,
>or for that matter as piano techs do to twist hammer shanks and the like? Could
>not a soundboard be crowned and ribbing in this fashion ? Would it be strong
>enough ??  Just curious.
>
>Richard Brekne



Beats me. It hadn't occurred to me. It might work just fine, or it might
not. There are a couple of things that would concern me, though. The
Encyclopedia of Wood tells me that heating wood lowers both it's modulus of
elasticity, and modulus of rupture. Getting it hot enough, for long enough
will do permanent damage. Even if the wood wasn't noticeably damaged by the
process, I think I would feel better machining a crown into a straight rib,
than forcing a curve into the rib with heat, when I am expecting the rib to
predictably carry a substantial load over a long period of time. 
 Ron N