> 'Course, none of this actually works - the ribs won't shrink much, the > panel top edge will just crush when it expands the 1/10 mm that it might > move and the rim has enough flex to negate any "arch" support. In fact, as my experiment written up for the Journal shows, if the panel is constrained from expanding by a nice firm buttress, the crown won't form at all if it isn't already there in the form of crowned ribs. It ain't an arch. That's pretty much a no-brainer by now. > But I think the first paragraph above is pretty much the reason the > practice persists. And in any case, even if it doesn't have any > significant effect, some minimal drying prior to installation is likely > to make most any rebuilder sleep better at night because s/he hasn't > offended the Goddess of the piano soul. I've seen (or think I have) what seems to be an amount of "squirm" in soundboard assemblies. Things *move* with MC changes. In anticipation and accommodation of such, I tend to want to fit the panel, rib it, locate and install the bridges, and glue the assembly in at as nearly the same MC as I can manage. When I do this, surprises seem to minimize, and predictability (and peace of mind) increases. A view from the trenches. Ron N
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