Just thought I'd revive an old thread, to add the comment; keep the D&M spindle drive card! It's a Puma SM, a good little motor driver. I've been using mine with PC-driven relay control, and manual speed selection, but I'm about to add the CNC4PC Variable Speed card too.
Also, my machine was converted by D&M from a manual Sherline, not the newer CNC version. Manual leadscrews don't have thrust bearings, and my X-axis recently galled up and welded the aluminum drive coupler to the 1" diameter leadscrew mounting plate(Sherline 40280) on the left side of the table.
Sherline parts are inexpensive, and high quality, but refitting all three axis with Sherline's thrust bearings would require their stepper mounts as well. Sherline's stepper mounts are .400" longer than the blocks D&M supplied, and I'd rather not lose .400" of my X travel (because of the enclosure.)
Instead, I added a counterbore to each side of the mounting plate, .060" deep, and .375" diameter, for a pair of miniature ball bearings. ( MSC # 35381532 )
I also removed the original snapring and thrust washer from the leadscrew, instead using a turned-down 1/4-20 nut as a thrust surface, to gain a little more shaft length from the sawn-off manual leadscrew.
'll be converting the Y and Z axis now that I've tried it out on X, although switching to all Sherline parts on those axis may be a better idea, as the Sherline stepper coupler and 5-40 bolt in the end of the leadscrew allow better backlash control than the D&M parts.
Pictures soon.