I'm using the ESS and actual servo's.. but the issue from being closed loop at the drive or controller should not be the issue.. if you are going step and direction, even if you miss steps, or lose an output for direction, the servos will still consider themselves in the correct position even though in actuality they could be anywhere. the bigger the machine, or the more sophisticated (tool changer) the more problematic this is. I can't even imagine what a 10hp spindle with a 6" cutter would do if it was suddenly told to go in the opposite direction at 12ipm while taking a 0.5" cut in the material.

And instead of rapid away from the part, your Z-axis makes a rapid move into the part while the spindle is turning at 1200rpm with that 6" cutter.

DUCK!!!!

So, no.. being closed loop at the servo (every servo is closed loop) doesn't resolve the potential problem.

Closed loop at the controller should fault the system if the motor is either going in the wrong direction or missing (or adding pulses).

Da-Dah!!!

I think a 14x40 hobby lathe can run easily without closed loop control.  I’m running a Hardinge CHNC only using stepper motors without closed loop control. I’m using ESS with an MB3 break out board. I’ve been running this machine on high volume production for at least a year without any issues. Granted closed loop with super precision servos is ideal but comes with a cost most hobbyists don’t need. Just my opinion.
Thanks
Art

I think a 14x40 hobby lathe can run easily without closed loop control.  I’m running a Hardinge CHNC only using stepper motors without closed loop control. I’m using ESS with an MB3 break out board. I’ve been running this machine on high volume production for at least a year without any issues. Granted closed loop with super precision servos is ideal but comes with a cost most hobbyists don’t need. Just my opinion.
Thanks
Art

Thanks for this information