Greg Postma wrote:

I posted a couple of months ago about my little Atlas/Craftsman lathe
that my FIL gave me. I've been playing with it and I discovered that I
have a runout of about .008-.009" with the chuck on. At the spindle I
have about .0005" (1/2 a thoushandth) at the spindle. It first, I
thought that I might have bad bearings on the spindle, but .0005" seems
pretty good, so most of the runout must be in the 3 jaw. Any suggestions
to get rid of the runout?

First, take it off the lathe and take it over to the bench. Completely
disassemble it. Get the worm out in your hand. Clean it immaculately, and clean
in there behind it. Then put it back on, and take out your feeler gages and
check the clearance between the center of the worm and the central boss. If
there is more than .001" there you have wear which can be taken up by carefully
placing one shim so it goes all around the central boss. Finally, clean the jaws
immaculately, then reassemble and test. Should get you to .003" or so -- that's
what you get with a 3-jaw. There are ways to make any 3-jaw into an "ajust-tru"
but it's quite a bit of work. Every 3-jaw needs tearing down every so often for
a good cleaning.

GWE