Having been bitten by the CNC bug ever since this, I'm interested in having a go at putting together a small general-purpose CNC mill.

Basically, I'm here to seek help on finding the general direction to getting started.

The mill is to have 200-300mm of X-Y travel, and 100-150mm Z travel, with 1/20000" resolution; the spindle is to be mounted on a moving gantry. I'm leaning towards building the frame out of extruded aluminium sections.

The machine is intended for cutting small aluminium or epoxy molds for injection molding of plastics, plus other things like milling gears and such like.

As I am a university student I will be working on quite a tight budget.

I have experimented with EMC2 and the Allegro UCN5804B Unipolar Stepper ICs, although the result was less than satisfactory (I may need a chopper driver)

Here are some issues I have so far:

1) As EMC2 seems to be the only free control software around, I've decided to go with it. The sim-axis setup looks sweet, but now I'm wondering how I would convert a 3D design from PTC's Pro/Desktop to the required gcode.

2) Referring to a CNC retrofit of a TAIG2108 for mold-cutting, my colleague told me he used NEMA23 276oz-in steppers, and the mill had 1/2"-20 ballscrews. What sort of controller (and motors) should I go for that will meet the above specs and not break the bank in the process?

Any help/advice/pointers would be gladly appreciated.