Soundboard installation, next topic : the glue

[Richard Brekne]

Alan !!... grin... so what are you telling me here ? I have reached the 
limit of the idealism embodied in the whole idea of the pianotech 
list... which attempts to embody the very core of human endeavor... the 
willingness to freely give of gained knowledge for the benefit of the 
common good ?  I just KNEW there had to be a catch somewhere... :)  And 
folks wonder at why I keep scratch'n my head over all this.

Seriously tho... it strikes me that a very short rib with a 4 foot 
radius in one place of the soundboard and a long rib with say a 30 foot 
radius.. (I have no idea if thats in the ball park of RC&S board 
designs... but those kind of numbers have been recently tossed 
around).... all pressed down to 25 % of their height unloaded by string 
downbearing pressure would subject the panel sandwiched in between to 
pretty wildly variants of compression degrees.  For that matter, without 
figuring the strength needed to reduce a short 4 foot radius rib to 25 % 
of its height.... I'd imagine you'd need rather a significant amount of 
down bearing.... which would equate to a very significant amount of 
panel compression... which would be increased even more significantly 
when the whole thing takes on humidity.

I'd just like to hear more about how all this works... I already know 
folks can build pianos this way that sound good.

Cheers
RicB


        ooh Ric,
        You're touching on trade secret territory here. You might just
        have to
        divulge your Credit card number to get answers. The Internet is
        a free for
        all but unfortunately not all for free.

        AF



     > Please then, by all means expound.  How much compression is
    imparted into
     > the panel with a typical RC&S design you are working with when down
     > bearing is applied so as to take the board to with in 75 % of
    flat... i.e.
     > leaving 25 % of original crown.  Take a panel dried to 6.5 %...
    specify
     > the rib radii for a three or four areas of the panel.  How do you
     > calculate the degree of compression created ?  This is a point I
    think
     > many of us would benefit from.
     >
     > Cheers
     > RicB