Didn't really answer your question did I Dave.

I was only "air cutting" the roadrunner on my mill, so as the error was only about 0.2mm I didn't notice a physical position error.
Steps away from zero varied from 1 to 80. on the DRO.
I just tried a "dry run" with only 5v and USB connected and it still does the same thing
Don't know if this is valid without drivers connected. S'pose it would not make a difference but I'll leave that to the experts.
