Why does nobody talk about how off-center soft jaws can throw your part tolerance?

Ran into this at a shop outside Detroit last Wednesday. Had a batch of 4140 steel rings coming out .005 out of round on a Mazak lathe. Checked everything - spindle, bearings, tool holder. Finally grabbed an indicator and ran it across the soft jaws. One jaw was shifted .012 from center. Bored them fresh and the next part was dead nuts. Now I always check jaw alignment before cutting. Has anyone else had a similar issue with their chuck setup?

2 comments

2 Comments

harperwright20d ago

Ngl, that sounds more like a tool holder issue than jaw alignment.

brooke7120d ago

Yo same exact thing bit me on a job last year with some stainless flanges. Bored the jaws out while they were loaded with a torque ring to simulate cutting pressure and it fixed it right up. Now I always indicate the jaws before running production.