Motor Size estimate?

Could anyone guess what kind of motor torque I would need to operate
the crossfeed of a 13" south bend lathe through either the existing 8
tpi acme screw or a 5tpi ballscrew (if I can somehow make it fit)?
I'm looking more for anecdotal examples from similar size machines
than theory, as I have no idea what cutting forces are numerically
(anyone ever build a load cell into a toolpost?)

I'm considering open loop stepper, closed loop stepper, and servo as
possibilities, probably with tooth-belt reduction.

(For my application, a sort of software tracer attachment, I can
initially get away with low-precision longitudinal feed - probabably
any old motor driving the leadscrew through the QC gearbox between
approximate endpoints determined by an existing linear encoder strip.)

Chris

--
Christopher C. Stratton, stratton@...
Engineer, Instrument Maker & Horn Player
(978)538-5179 work, (617)492-3358 home
30 Griswold Street Cambridge, MA 02138
http://www.mdc.net/~stratton