The shape of the grooves sure seems peculiar. Maybe washers of some soft
material that had a slight lip around the circumference were intended to
sort-of pop into those grooves.
It looks as though only the ends of the grooves have the dovetail shape
(nearest the case-half parting line).

I'd probably situate a thin metal washer (resistant to grinding sparks) at
the outer location, followed by a felt washer in the space behind it, maybe
followed by another hard washer in one of the other grooves to loosely
constrain the wool felt.
Small clearances should eliminate any friction or heat being generated
during use.

Another felt washer adjacent to the bearing may catch any moving dust,
preventing it from getting into the bearing assembly (even shielded ball
bearings aren't dust-proof, and dust buildup will absorb the lube out of
them). A drop or two of oil on the felt near the bearing may prevent the dry
felt from wicking the lubricant out of the bearing.

It would be hard not to like the concept of free tools.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Bob Engelhardt" wrote in message
...
I found a Makita die grinder at the dump. It had a bad bearing, but I had
one in my collection (I just love when it works that way!).

The question is about some grooves in the case & matching ones in the
spindle:
http://home.comcast.net/~bobengelhar...derGrooves.jpg

At disassembly they had gunk in them, I assume some kind of very old
grease. I also assume that the purpose is to keep dust out - these are
not bearing surfaces.

Does that sound right & ,if so, what grease should I use in re-assembly?

Thanks,
Bob