import 6 inch chuck, runout, am I the problem

New 6 inch three-jaw, the import one surplus_pat had last month. Indicated the body and it's fine. A piece of ground stock in the jaws shows about three and a half thou. I can indicate a part in a four-jaw all day so I don't think I'm haunted. Is this just what these chucks are, or did I get a bad one.

That one was in the lot from the Pasco sale, I didn't mount it. Three thou on ground stock in a three-jaw isn't a surprise on the cheap ones. I'm not going to tell you it's a Bison. If you want it gone I'll take it back off the lathe price, you eat the drive.

You're not the problem. The chuck is. 'Just indicate it' doesn't fix a three-jaw, that's not what a three-jaw is for. Send it back or live with a roughing chuck and stop putting ground stock in it like it'll repent.

Did you check one jaw at a time, or only the assembled runout? A single high jaw will look like this and the body will still clock true. If all three are high in the same way, it's the scroll.

One jaw is the whole story. The other two are close. I'm not taking the lathe apart over it. It'll be the roughing chuck. Pat, I'll keep it, I don't want to ship a chuck over this.

Mark the bad jaw so future you doesn't rediscover it at 11pm. Number is about 0.09 mm. Fine for rough. Not fine for a shoulder you care about.