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I recently set up a used KO Lee S714 surface grinder and was a little
disappointed at the finish, though my experience on these tools leaves a lot
to be desired. The surface almost seems to have very shallow scallops at
regular intervals. They can't be felt by hand and a fingernail doesn't catch
anywhere. There is a bit of noise as the grinder winds up but that seems to
be coming mostly from the motor. The grinder appears to be in otherwise
very good condition.

I checked the spindle runout with a gage head and amplifier and am seeing
about 0.00075" with the gage tip on the tapered spindle nose (wheel & collet
were puulled off and belts between spindle and motor were removed). I can
also get about 0.0015" deflection in the spindle by manually pushing or
pulling the spindle toward or away from the gage tip. The spindle feels
reasonably cool after running for 45 minutes without a wheel or collet
mounted.

This seems to be pretty far out of spec to me, but opinions would be
appreciated from those that know better than I.

If this does need attention, is there any chance that the bearings just need
adjustment? There's a circular disk threaded into the outboard side of the
spindle with holes for a pin spanner wrench. I haven't mucked with that yet
but presume that it's there to adjust bearing pre-load.

If the bearings need to be replaced what are the chances of being able to do
this myslef? A manual for a slightly different KO Lee grinder suggests that
spindles must be returned to the factory for rebuilding.


The runout seems excessive, .0002 max would be typical for
a new grinder spindle, and there should be virtually zero
free play, if that's what you mean by "0.0015" deflection".
Preload in something like this is not normally adjustable,
but is determined by the bearings themselves and the
spacers that separate them.

You may be able to replace the bearings yourself if you're
careful and educate yourself enough to know when to charge
ahead and when ask for help or do a bit more research. As
far as returning to KO Lee goes, there are dozens of other
spindle rebuilders who will repair virtually any spindle.

Ned Simmons