If the arduino mega is a little slow, any thoughts on using Adafruits new Grand Central as replacement? It's a lot faster, 32 bit, has the same layout and form factor. Only downside seems to be 3v logic. I've been thinking of using it when i get to the control hardware part. Thoughts?
https://www.adafruit.com/product/4064
Also i've been thinking of using uSteppers on some of the axis anyone has any experience with them?
http://www.ustepper.com/index/
3.3V ouput works well with 5V TTL logic but won't with CMOS.
The question is which driver use which logic.
My CNC use DQ542ma's driven directly by outputs of a cortex M3 (LPC1768) which is 3.3V. Wires needs to be short and the wiring is different: you provide common GND and the controller provide VCC to EN, DIR and STEP.