Having found limitations in the number of grinding options with one 40yr
old sears 6" grinder, one of which shafts has a heavily used wire wheel
and the other a coarse grey wheel, the first HF tool grinder I bought
6-8yrs ago worked nicely with a supplemental Alox wheel from J&L, about
$20 and 60grit. The Alox was just a bolt on plate mount. Some time
ago I used a coupon to get one of the diamond plate mount wheels from
Enco, perpetually offered in their hot deals monthly for $93, a 200 grit
wheel. It looked like a bolt on but is a thick disk of steel with a shallow
layer of diamond on the steel facing. Took advantage of the recent thread and
got a grinder for $108 and a stand at HF. Found that the big nuts
on the end of the shafts are to hold the mount plates on and the mount
plates are a bit rough around the edges. Easy enough to touch up the
rough spots with a lathe tool. Mounting the diamond plate was a no
go: first problem, center hole 0.040" too small. Five minutes of mounting
the wheel in the 4J on the 12x36 lathe and indicating to a few thou
concentricity and the bore was large enough to fit over the shaft. Now
problem 2: mount holes are ~0.25" deep, usual plate mount wheel has
plate ~1/16th thick, not 1/4", so bolts too short. Brief experiment with
SHCS 8Mx20mm showed the bolt circles plate and wheel just a bit off,
enough that could not use all 4 holes. But, there is a second bolt circle on both mount and wheel for 6M bolts. This bolt circle worked so the diamond wheel is mounted with SHCSin the 6M circle. I was concerned about off center mount and vibration but the diamond wheel spins smoothly and no difference between the two machines. Spin down times are about 55 sec for the new HF and 60 sec for the old one, both have a brief bit of vibration at some speed.
FWIW all the 'green painted' wheels from both grinders are marked 80
grit. Diamond wheel does nicely touching up carbide, but eventually I
need to find or make one of Forrest Addy's CI lapping wheels that is charged
with liquid suspensions of diamond grit, they really polish up a carbide
cutting edge.