So what this means for us is that we can use TouchDro and regular hybrid steppers.
We need a way to manually control the stepper speed for a power feed. A circuit that automatically prevents both the powerfeed and cnc being used simultaneously (should also be simple). A driver that will accept feedback from the dro scales, and possibly a microprocessor to ensure that the cnc read rate from the scales is not interfering with the dro read rate.
BTW, I spent hours looking at scales before I finally found this set up
Wholesale Product Snapshot Product name is High precision 0.001mm mill and lathe DRO kit 3 axis digital readout and 3 pcs 1um 0.001mm linear scale
This is a 3 axis 1um glass scale dro system for about the same cost as purchasing just two class scales from DroPro (who have the best price for scales). Since I plan on using TouchDro, it does not matter if the display is junk since I am after the scales. In fact, the system is only marginally more than the better Igaging scales, and the Igaging scales are +/-.001" per 6" (pretty crappy).
I looked at hundred if not thousands of motors before settling on these
http://www.automationtechnologiesinc...flat-570-oz-in
This motor has a 2.5mH inductance, which equates to an optimal voltage of 80v, and a convincing 5A current draw. Nearly every motor I looked at has a far higher inductance, meaning that you will not get optimal voltage with out an industrial driver. This also happens to the same motor they recommend for x and y axis in there GO704 cnc kit.
I am trying to figure out the cheapest solution for running the stepper as a power feed.
Something along these lines is probably what I will go with
Stepper Motor Driver Controller Speed Regulator Pulse Signal Generator Module | eBay
Ideally, the speed controller should have a pot for adjusting duty cycle as well as frequency so that the motor can be made to start/stop smoothly.
Lastly, I am thinking a transistor between the motor and the controller for when the mill is used manually. Set it up so the transistor closes when power is applied to the motor, but is open otherwise. This way any voltage made by the motor when turning the dials by hand will not go anywhere (or to ground).
Let me know your thoughts, maybe we can figure something out together and get some useful input from the community.
-Josh