On 8 Oct 2003 18:01:56 -0700, (Steve) wrote:

I have a 8" 3 jaw chuck that I got with my Sheldon. It is rusted and I
cannot see any marking on it anywhere. I also cannot see any markings
on the jaws or the body of the chuck that advise which jaw goes where.
The problem is I chucked up a piece of round stock and it had over
.015 runout. I then got a piece of drill rod and it was the same. That
is of course unacceptable. So I checked the spindle run out and it is
in the area of .0005. I believe that is mainly due to the vibration of
the lathe. The thread on the spindle amd the backplate is a 2.25"x8.

So I took all of the allen head bolts out to seperate the backplate
from the chuck so I could check the runout of the backplate. There
were 6 bolts around the outside and 6 bolts around the inside where
the through hole is located in the chuck. The backplate will not come
off. I tried a deadblow hammer. I tried a cold chisel to try to
seperate the two and I tried WD40 to try to break it loose. It did not
budge. Any suggestions on how to get the back plate off? I kicked
around the idea of making a dummy spindle and threading it. Then screw
it into the backplate and give it a whack with the deadblow. Only
problem is I don't have any stock that big right now. Any other ideas
greatly appreciated. Thanks, Steve

close the jaws gently around a chunk of pipe or bar stock, that will
fit in the chuck, but touch the back plate (some chucks will allow this,
others will not. Then bang the pipe straight down on a nice chunk of
plate steel on your floor. Repeat as necessary.

There IS a possibility that you have two jaws out of place, but
generally that will show more than .015 TIR... more like .1 or more.

Gunner
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.