Lathe chuck

First thing to do is indicate the chuck outer body and make sure that it's running dead true--oftetimes the mounting boss on the backplate has been intentionally machined a tad bit undersize and so it will move off center given even a fairly mild mishap.

Only after doing the above should you re-grind the masters--and at this point I would suggest also mounting up your hard top jaws onto the masters and grinding them at the same time which allows for more contact area along the workpiece length.

FWIW, major reason to indicate the chuck body isn't necessarily to correct for runout--it's actually done to allow runout to be kept reasonably low without also causing excessive vibration to occur when running at higher speeds.

And with soft jaws, it should go without saying that they will always need to be bored the first time you use them at the very least...and so it's better to balance your chuck before, than after.....

Masters do not toch the workpiece. no need to touch them.

Will indicate everything shortly.

Remove 333 to reply. Randy

Mine do--but the fact is I usually don't run any top jaws at all...it's a manual chuck and on a manual lathe though...pretty sure it's a Cushman.

( my cnc lathes are all swiss and so they run collets and a synchronous bushing )

Git er done, my man...

Total TIR of chuck body 0.0003" put a bar in the chuck and tried to see if there was up and down play. Could not move the indicator even

jaws have about .015" radial play and about .007 axial at the tip where they would touch the workpeice and about .003 on the back end.

Thia is a Kitagawa power chuck and the most play is radial where the master jaws run on the clamping ramp (or wedge) whatever it's called. Wear here would give the most problems in concentric clamping. Right?

I think a call to Kitagawa or a chuck rebuider is in oder and see what they say.

Remove 333 to reply. Randy

Kitagawa was kinda useless, All I got there was sent it in with $300 and we'll inspect it.

Remove 333 to reply. Randy

I got some real numbers to go by from worldwidechuck.com. My chuck slop exceeds all of them. Won a brand new chuck in the factory box off EBAY, for about 1/3 price of new. Will see what It's like when I get it.

Remove 333 to reply. Randy

Thanks Randy appreciate the update.

Used the new chuck, very nice. Can't say much for the factory chuck grease, it was flying out all over the place, made a nice white ring around the inside of the lathe. I think I'll stick with the Moly stuff I was using.

Remove 333 to reply. Randy