Rib Crowned Hamburgs ?

[Ron Nossaman]

> "...the same as pure rib crowning procedures so enthusiastically debated 
> back and forth on this list..."
> 
> It may essentially be pure rib crowning they employ (much to my 
> surprise, for sure), but there is more to designing a soundboard than 
> crowning a rib. What is the taper design? What is the rib array? Rib 
> dimensions? Rib radius/radii? Radius/radii of caul(s).

And rib crowned is not necessarily rib supported, as we have so 
exhaustively and repeatedly described. Most pianos these days seem 
to be rib crowned, but bloody few, if any, are rib supported. 
Calculating loads and deflections from string scale and rib 
dimensions will tell, for those who truly care to know.

Also, if the ribs ends curve more after feathering, that can only 
come from panel compression. Either the panel is dryer than ambient 
room RH% on assembly, or it's pressed into a caul of tighter radius 
than the ribs when the ribs are glued on.

Ron N