[keen]

Is'nt the only reason why you would go closed loop or servo....if you were having problems losing position?

But this just doesn't happen unless you have a specific machine fault......

Please explain why.......

Keen

[PCW_MESA]

Is'nt the only reason why you would go closed loop or servo....if you were having problems losing position?

But this just doesn't happen unless you have a specific machine fault......

Please explain why.......

Keen

Here are some reasons to use servos vs step motors/drives:

1. Size (step motors only get up to a few hundred watts before they are not cost/performance competitive with normal servos)
2. Higher speeds are possible and you have much less steep torque drop-off with speed
3. Better accuracy ( because of the feedback, good servos can provide more accurate motion with dynamic loads, stiction etc )
newer servos are capable of extremely smooth motion even at very low speeds (the latest Fanuc encoders have 16/32 million counts per turn)
4. If the feedback goes to the controller you can restart from a fault without re-homing and
if you have absolute encoders you may never need to home
5. More accurate homing (if the hardware can home to encoder index)

These may or may not be all that important to Mini mills/lathes