J wrote:

If this is not a troll, the answer is to simply turn the belt sander 180
degrees.


I hope I could have made it more interesting if it was ;-). I should
have mentioned that I was talking about one of these:
http://www.leevalley.com/wood/page.a...84&cat=1,43072
which suggests a motor turning in a 'counterclockwise' direction - but
as viewed from over the motor or straight at the shaft? (Pardon my
mechanical ignorance.) As you can see, you can't really turn the whole
grinder.
Re. the rotation of grinding wheels, I don't see how the arc of the
wheel is any protection against dig-in. The back of the blade is still
going to be ground away at some point and this is where dig-in would
occur... I guess the idea is that the force on the tool created by
friction with the abrasive is directed toward the tool rest so the tool
doesn't threaten to pull up. The abrasives must be uniform enough that
you won't get a lump of something coming along to dig in to.