Stepper motor replacement ?

[PBD]

Hi everyone,
I have a homemade 6040 cnc router run by a Gecko G540, I recently had a prang in z axis and need to replace the stepper motor.The spec of my motor is Nema23 600oz in 3.5A. 3.9 mh. it came in a kit from the US.I have found a similar motor at Cnc4u uk spec is Nema23 4Nm. 4.2A 3 mh. Will it run ok with my existing mc settings?.I am happy with the holding torque at 4Nm but do not really understand the other specs ,any advice would be much appreciated.
kind regards Phil.

[m_c]

You'll only get that torque if you run at the full current.
The lower inductance allows faster current changes, which ultimately results in better performance.

Unless your machine is pushing the motor and driver to their performance limit, the other motor will probably fine.

[PBD]

Hello,
Thanks for the advice ,I have had another idea how about I go to a nema24 the hole centres are no problem to fix .Stepper motors online have one nema24. 4.2Nm. 4.2A. 3.3 Mh 4 wire bi polar would this be a suitable replacement ? .Thanks again look forward to hearing from you .kind regards Phil

[JohnHaine]

The second one you mention still needs a higher current and gives you the hassle of changing the hole centres. The first would probably be perfectly fine and I wouldn't be surprised if the drivers you have allow you to tweak up the current from 3.5A to 4.2A if you find that you don't have enough torque.

[m_c]

The G540 (essentially four G251s in a box) is limited to 3.5A (plus they're set via a resistor mounted in the DB9 connector, which can be fiddly to change).

Personally, I'd just go for the Nema 23. Worst case scenario is you loose a bit performance, but on a Z-axis, that's not likely to be a major problem.