How can I center a thee jowl lathe chuck?
not rqd to set its self centre..some time due to jaw error der is a possibility of error dat time u can adjust it by light hammering and tail stock support..
surrounded by 4 jaw u can use dail for accurate setting and circle which engraved on jaw for hasty setting...
Some chucks such as the "Buck Adjust-True" have alignment screw. Put a precision machined rod in the jaws and align using a "clock" or dial guage.
If not, you can correct a "self centring" 3 jaw chuck by remaching the backplate or making a trial one.
Keeping your chuck clean and storing it with the jaws down when not surrounded by use can help it's accuracy. Source(s): http://www.lathes.co.uk
If it is not centering by itself, the first thing to do is clean it thoroughly, conspicuously the scroll and mounting surfaces. If it is dramatically off, check that the jaws are in the correct slots.
If after that it is still bad, you might consider grinding the jaws, but if the scroll is worn, that may only correct for one diameter.
Three jaw chucks are almost always self centering. 4 cheek chucks are not.