Cut off bar & fish pictures on Mason AA (Modified by Kent Swafford)

[Erwinspiano@aol.com]

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Hi Dave
   Yes they are pared some but not as  much as the originals and the material 
 in the pare  is thicker than it looks in the picture.. The ribs are also 
White spruce  & are taller than wide & stiffer than the original  sugar pine. 
    I use what I call a variable radius  approach to crowning as do others. 
Meaning increased radius as the ribs get  shorter. You know this I think.
   Keep in mind that a tight grain tongue &  grooveSitka board which I use & 
white or sitka ribs  are  intrincsically stiffer materials than the eastern 
spruce &  sugar pine combination that was customarily used in Stwy & Mason  
pianos . In conjunction with a fairly thick Sitka  spruce board (.350) & without 
much thinning in the top area it will be  plenty stiff I assure you.
  I mean after all how stiff is stiff enough? That's  always the 
question.This board will be 100% stiffer than it was & crown  longevity
   The ribs have a  radius from 55 ft in  the bottom graduating in to 25 in 
the top. Adding the fish & shortening up  the Treble  ribs & removing some 
soundboard area has  made  the treble area  way stiffer & should help the overall 
impedance  characteristics & improve tone. 
   That's the idea as I understand  it
    I dry to 5.5 %To 6% in general am happy with  this small amount of 
compression. If it goes to a drier climate i.e. Nevada then  5% makes me feel better.
   Regards
   Dale Erwin

Dale:

I notice on the ribs that the scalloping of the ribs seems  traditional
in its approach which is a fairly severe downward cut at the  beginning
of the scallop so that the ends of the ribs thin fairly  quickly.  To
what degree are you compression versus rib crowing and  does that style
of scalloping not weaken the rib at a point at which it  needs to bear a
significant portion of the load?

David  Love
davidlovepianos@comcast.net 





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