Thanks for the quick feedback, here's what's happening:
I've set up a dial indicator on any given axis...let's say X. I'll zero out the Mach3 DRO. I'll move any distance on X, for example .1 inch or 1 inch, it really doesn't matter, and then move back to 0. I'll reset the dial indicator to 0 to remove backlash error. I'll repeat the move, 1 inch (same direction as before) and then back to 0. When I return to 0 the dial indicator has changed by .001 (that is if I'm using 1/2 steps, its proportionally less if I'm using 1/4 or 1/8 stepping). If I repeat the roundtrip move, I'll be off by .002" and each round trip the offset continues to add up. And this happens on each axis, exactly the same.
Of course when I move away from the 0 axis to the midpoint (.1" or 1" away), the backlash comes into play and the indicator doesn't match the exact given distance, I understand that. But when I come back to 0, I'm always off. Each round trip loses another .001".
This is confusing to me because I've tried nearly everything. I don't believe its a mechanical issue, everything seems to move smoothly, but I could be wrong. It just seems like the system is dropping a couple steps each time it makes a move.
Please let me know if I'm missing any information in my description, I want to be clear and I certainly appreciate the help.
Troy