Joseph Gwinn wrote:
Well, I think I finally figured it out, although there is still a
mystery.

{.....]
Joe Gwinn

A quick question how accurate is your chuck and the mild steel material,
are the jaws worn and not gripping the piece fully. I had troubles
holding and turning some 310 stainless which turned out to be the
stainless being slightly triangular and that spiraling down the piece,
the 3 jaw even though quite new would not hold the material well until
a skim cut had been taken to make it round.