[Andy Brockway]

The problem may be with the lathe or chuck. I check the run out of every piece I turn prior to cutting the first chip. I am fortunate to have a set-true tight chuck so I can correct the run out prior to starting my machining.

In the three jaw chuck you can sometimes adjust the piece more towards center by tapping with a soft (plastic) hammer while checking run out. Best is .001 TIR but I have also made parts at .002 TIR.

It is interesting that the hex collet is also causing trouble. Check the mating surfaces between the lathe, collet closer and collet for grime/debris. Check the run out of your piece after chucking. Possibly you can tap to adjust to center.