I have analogue drives (DQ860MA) and when switching on there is a thud from the steppers depending on how far they are away from a whole step and the ballscrew rotate slightly. Normally this is fine as I home the machine etc. but on a recent job I was surfacing a part and had to stop part way through. I wanted to keep the Z height exactly where I left off so I attached a DTI to the Z axis switched on (which moved the needle slightly) and then I jogged it back to zero.
Out of interest is there any way of knowing before switching off how far the stepper is from a whole step? I know some drivers have the feature of remembering which micro step they are in but is there any other way of knowing using the drivers I have now?