Jim wrote:

Just wanted to thank Gunner for his excellant step by step essay on
replacing spindle bearings on an old chucker I picked up.I have the
bearings and about to install them but curious about some numbers I see
on the spindle itself (8 and 3) next to the bearing location and the
instructions from the bearing box sais to line up the #'s of maximum
radial eccentricity of the bearings 180 degrees oppisate of the shaft
and housing eccentricity. I am assuming these numbers on the spindle
designate this although Gunner did not mention anything about the
spindle or housing runnout.These numbers are in microns and I figure
that translates to .000003 of an inch, the bearings are marked 2 and
3.Personally I have no concept of how this eccentricity is measured
especially 50 years ago when this spindle was originally ground? This
is the first time I have dealt with such precision bearings and would
like to take my time and learn to do it right the first time. Thanks
for any input on installing or how the hell someone measures to six
decimal points. Jim

http://65.204.160.42/index.php?id=788
ideas?