Rob McDonald wrote:

I am turning to a groove at a shoulder. I am afraid that the tool will hit
the shoulder if it is too fast.

Does your chuck thread onto the spindle? If it does, is there a way to
prevent it coming loose or could you make such? My chuck is held to the
spindle with three bolts so I needen't fear it coming off when cutting
in reverse. Thus I place my threading tool _behind_ the work and cut
with the machine running "backwards" to the usual. The _huge_ advantage
of this is that there is zero chance of running into a shoulder. I
simply run off the end, retract the cross slide from its pre-set zero,
run back beyond the shoulder, hand move to the start, reset the cross
slide, advance the compound and take the next cut. I know it _sounds_
complicated but by the time you've done it twice it is faster than
running at such slow speeds.

Ted