ATM Bushings

["Larry Davis" <Davis@digdat.com>]

    I have an equitorial mount that has brass bushings instead of ball
bearings for the RA and Dec axles. The dec. axle is very smooth in its
movement. The RA axle on the other hand still has some snug spots ( one
especially) as it is rotated. I've removed the bushing and found that it is
wearing in 3 areas ( aprox. 1.5" long ea. on a 4.25 id bushing ) that are
spaced about the inside of the bushing roughly 120 deg. apart. This same
bushing is made with a flange on one side to serve as a thrust bearing by
riding against a shoulder on the RA axle.
    Now this is where I could use some help. when the bushing is placed on
the axle(bushing only) it turns freely but with the full mount in place it
tends to bind in certain areas.
    Of course I could use some lapping compound to open up the clearences
and seat the bushing however, If I do this it will at the same time
increase the slop in the mount and I'm not sure this is the problem.
    Any comments or suggestions appreciated.
    LD

BTW there are 2 bushings on the shaft spaced 5.5" apart, they each have a
clearence of 0.004"