[pianotech] Belly talk

[Jim Ialeggio]

Dale,

Yup, that's the idea. Mine had about an 11mm crown (notice the word 
"had"<G>). on the belly rail.  It also had a crown along the curved side 
of the rim following the crown of the long bridge, though less agressive 
than the bellyrail.

I did some math on the actual amount the treble glue ledge would need to 
be beveled off of flat to "match" the crown arc.  On a short top rib, 
with 3/4" wide glue ledge, 165mm working rib length, very tight 4M 
radius rib, the difference in height between the point where the panel 
first hits the glue ledge, and the back of the 3/4" glue ledge is about 
.006"(.15mm) or .5 deg...about the thickness of a glue line. On a 
normally radiused rib, the difference would be even less. So the amount 
needed to avoid undo stress, if one feels that's necessary, seems to be 
quite negligible, at least to my mind.

But thankfully, lots of different design scenarios seem to work...and 
good thing for us too.

So, you guys who work on a lot of S&S's, it looks like this kind of rim 
crowning profiling seems not to be a common feature...no?

Jim Ialeggio


-- 
Jim Ialeggio	
jim at grandpianosolutions.com
978 425-9026
Shirley Center, MA