BTW, does anyone in their right mind try to lap tools on the side of a
wheel? I've never tried it but it seems to me it would have all the
effectiveness of flattening a table table top with a belt sander.

a belt sander is an appropriate tool for flattening a tabletop if the
table top is starting from a flatness of less than what the belt sander
can produce. after that you'll prolly want to progress on to something
with a bit more finesse.

Have you ever tried it?

I think you may have missed my point. A tabletop so something which will
show a dig-in mercilessly. This is simply beacuse your face gets close to
it, often with light reflecting off it at an angle. I know that you *can*
flatten a table top with a belt sander, but you had better have quality unit
and more importantly a well-finessed touch. I would venture to bet that in
most cases beltsander + tabletop = mess.

It's really the wrong tool for the job and is particularly prone to creating
more of a problem than it solves.

-Steve