Posted for "John Schroeder" <jschroeder@perigee.net>:

 Harbor Freight also sells a set of diamond crusted tools for a dire  grinder
of all sizes and shapes. There are 30 - 40 of them in the  box-holder. We use
them all the time and they seem to hold up well. They  go on sale from time to
time for about $16.
 
 The one we have used the most is a wheel 3/4" in diameter and about 3/16"
 thick. It also makes very short work of prepreg core. There are also several
other sizes for this in the kit.
 
 Gotta get one of those Permagrit countersinks. The ones we have seem to  get
dull awfully fast.
 
 Cheers,
 
 John