Power chucks...

A fellow in the UK "motorsail" designed and sold bits for a
centrifugally operated chuck for some type of spring collet.

I recall that he machined a small groove or shoulder at the end
of the workpiece, turned off the spindle motor, which released
the grip, moved the toolbit into the groove, moved the carriage
the "right" amount, started a new cycle.

The "right" amount included compensation for back-pull of the
workpiece as the collet closed (it was pulled back into its
taper). Of course, the program could always reface the work
piece after each feed, so the amount of pullback wouldn't matter.

/mark