Stephen wrote:
On Tue, 22 Sep 2009 18:36:03 +0100, Harry Bloomfield
wrote:

a 6" and an 8" grinder.

I have been browsing a few online shops and it occurs to me you may
have one machine with a 6" wet wheel and an 8" dry wheel. Is this
right?

Go to your local 'shed' and look for one. If you find one, spin the
smaller wheel with you finger and see how fast the other wheel spins. It
must be slower, otherwise. you have got the wheels mixed up.

Wet wheels are usually larger and wider.

Dave