Just thought I'd share with everyone my X3 conversion. All the information gained from the fine folks here and on the EMC2 mailing list went into this puppy. Gallery Here
It's still a work in progress and I plan to post detailed drawings and models so that others can emulate if they choose.
Simply put it's 300 in/oz steppers on the X and Y direct drive, 600 in/oz on the Z at 2.6:1 ratio via timing belt. All the screws are Nook 0631-0200 XPR precision rolled with SRT nuts (5 tpi screws). Double nut on the X with compression preload instead of tension, single oversized ball preload on the Y, and just the single unmodified nut on the Z. All screws are secured in VXB angluar contact bearings - I couldn't justify the expensive stuff from the big names.
I'm driving the G203V's @ 53VDC from a toroid transformer. The PC is a curbside find - an old Gateway P3 650MHz with 384mb of memory. It's not much but it's enough to run and get the job done. Complex jobs take a while to parse, but run fine.
I moved all the electronics from the X3 column out of the column and into my driver enclosure. No reaching past the column anymore. Hope you all enjoy. Any questions - fire away.