Hi Ady,

Mach3 does not have a closed loop system built into it. You can interface the glass linear scales with the DRO but the engine inside the software will not be able to correct for deviation in position. There is a plugin somewhere that will stop the program if the deviation of measured position vs estimated is too large.

As long as you use good electronics and actuation hardware, backlash and lost steps are minimal. Backlash is manageable anyway through Mach3. So you can get professional quality results with an open loop system. On my machine with a Newall 5micron accuracy/resolution scale, I am happy that my DRO and Mach show an almost identical number.

To avoid lost steps from the stepper motors, you will need to consider a motion control board and not use the parallel port. There are many motion control boards out there so choose the best you can for your budget. (ethernet ones are better) Cabling and cable routing is also cruicial.

If you want to close the loop, you will need to buy a KFlop board and learn to program it. If you have the skills it is a nice project and gives good results.