Simple Step Motor and Control

Your accuracy will depend on total division ratio, stepper PPR and quality and system backlash and rigidity, not rotation direction. Cutting vibrations are usally the problem not absolute accuracy and it will shake object at whole backlash distance and then some. Anyway for this application microstepping is not adding too much and division (assume 30 or 60 to 1) is big enough so a simple unipolar or bipolar driver like L297 based and a small NEMA 23 or even 17 stepper is enough. I would also go for a custom turned link to keep motor and divider system compact. S.M.

You might also just try

http://www.mpja.com/prodinfo.asp?number=17451+MS

or

http://www.probotix.com/stepper_motor_drivers/

Artsoft is my recommendation for control. As for an indexer, too many possibilities...

Steppers and links to other good resources

Good info Johannescnc, but my lord, the guy says "Basically this is to be used for ornamental turning."

You do not state actual application loadings, but you should remember the following.

The stepper motor is not a rigid precision positioner, it reacts to any force trying to displace it from its "present" position, and this implies a displacement to react to.

If the holding force is overcome it will move to its next holding position, which will be a movement of the "natural pole" of the motor (eg 1/200rev), not the driving distance (eg 1/1600rev).

In a precision way, you are right to assume that always moving in the same direction will improve the accuracy even with direct drive, as the position stopping (being reactive to load) will depend on the friction drag (if you ignore stopping Inertia!).

Your application may require a positional lock (or brake), which for precision will present it's own problems.

A Stepper motor or for that matter any motor will be affected by output loads and may not give accurate indexing.

A positive indexing drive like a "Geneva Mechanism" with a worm gear reducer could be a good option