Personally, I would never use a grinding wheel at more than
its rated speed. Never.

I am curious though why grinding wheels explode.

What are the typical reasons for a wheel going (assuming
it is not being spun faster than it was meant to) ?

One fellow mentioned grinding aluminum. What happened there?

What is the best way to get a wheel to go?

I would imagine that it is not a common occurance when the wheel
is not abused otherwise we'd hear about it more.

I recently picked up a 3/4 HP Baldor pedastal grinder at Boeing
Surplus that looked like a wheel blew up. The cast iron side guard
is in 2 pieces and the wheel was fragmented when I got it. From what
I've read, a good way to fix the side guard (cast iron?) would be
with nickel rod--any comments?

Jeff Dantzler
Seattle, WA