Soundboard types.. was The soundboard bit.

[Erwinspiano at aol.com]

RIc
    In my practice when someone orders a An RC  board the ones I make will 
transfer much of the load bearing  capacity to  the ribbing. Be aware that  in 
my RC boards the ribs are made taller  & of stiffer materials with tight radii 
The compression componenet will  vary between 5 to 5.5% mc at time of pressing 
depending on what type of climate  the piano is going to.  Nevada/Arizona 
etc. gets the lower  MC & the bay area gets 6% or higher. In either case, because 
of  prevailing MC in the mentioned climate, the panel compression will end up 
being  roughly similar at there final destinations. Customization is great. 
If I  had to ascribe a percentage of crown support from this type of board I'd 
just be  guessing at 20 to 30% as opposed to a purelly C.C. design.
  All boards must benefit from the interface..hey it's a  form of plywood. 
Beyond that it's many variable dynamic stresses in the panel  that make it 
work....or not.
 Dale

A RC  board can be said to have curved ribs... but beyond that it can 
either  rely largely on panel compression and the stress interface this 
creates  with the ribs, or it can be a pure RC and S board.  All depends 
on  how much compression the whole assembly process ends up putting into 
the  board.

Cheers
RicB


 
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