Supporting a grand in the shop: legs vs truck

[Clark A. Foerster]

Hi everyone,

After doing soundboard and bridge work on a Steinway M, I am now ready to
reinstall the plate.  Currently the piano is supported on a self-made
(4x4's, plywood, casters, 36"x48" footprint) truck (ie, elevated dolly).
The front of the piano contacts the truck on the bottom bridge which floats
under the middle of the keybed.  The damper levers and bearing blocks are
not supporting any weight. The three leg buckles have been removed.  The
tail is supported on a portion of the small console or leg connecting board
with a couple 2x4s to level the piano out.

Without the weight of the plate I have felt comfortable with this setup.
But now that I am ready to refit the plate I am curious about something:
shouldn't the plate be installed in a piano that is being supported at the
three leg points on the rim where it was designed to carry weight?  What if
it were supported on its braces and the keybed itself?  Would this make a
difference to how the case responds when the plate is cinched up tight?  Or
is the case and keybed so rigid that it doesn't make a signficant
difference where on the case the piano is supported?  I am concerned here
with the weight of the plate on the case (inner rim) and how a cinched up
plate acts on the case.

I have heard of plates flexing slightly when tightened to the inner rim
but couldn't the opposite also happen?  If it does, then tightening the
plate up with the piano's three legs attached on a level floor seems, to my
novice mind, desirable.  But for the sake of my own convenience I would
like to keep the piano where it is on the truck.  Any thoughts on the this
subject would be appreciated.

Clark Foerster, RPT