rib glueing and panel compression

[Erwinpiano]

Hi Ron
Enjoyed  your usual succinct and clear technical thoughts on the subject of
recent interest on the list.I n your  current catalogue of various
soundboard forces senarios you mentioned that in the pure forced crowned
board, only the compression of the panel is creating the crown and that the
ribs being flat are actually resisting that effort which I agree but as to
downbearing I have this thought. I no longer think that the compression of
the panel is the only force opposing the downbearing in this type of
construction..I have heard that some who use this method allow the boards to
puff up a bit before glueing them to the rim which does bend the rib further
I,m thinking 40% R.H..Once that bent rib is anchored in the case the ends
can no longer move as much..It,s true that they can unbend some of course as
the panel shrinks or cracks or even self destructs  but I have so often
removed boards the had some crown with strings removed  that once off the
rim totally flattened out . My point being that those force crowned ribs
once glued in position where an essential  part of the equation in
contributing to the resistance of downbearing and also because ofthat making
tonal contribution.what do think ?Also all those pianos from the past we
admire so much all used a procedure we all no longer think wise to embrace.
But wow they really sounded great.! sincerely Dale Erwin