View Full Version : understanding stepper motor ratings.

29-09-2013, 10:08 PM
Hey, so I've been looking on my new favorite site, Aliexpress :D..

and have been looking at stepper motors,

from what I under stand all nema 23 motors have the same sort of face profile so the longer the motor, more juice it needs and more torque it has.

but how is it, that the nema23 stepper motors from CNC4U are 3.1nm and only 88mm long but on aliexpress a nema23 motor with a length of 115mm is only 2.5nm :confusion:

my only guess would be that these readings are taken at different voltages? :S

if so should I buy on length or holding torque?


115mm nema 23 motor (http://www.aliexpress.com/item/3pcs-lot-A65-Lengthened-Hybrid-Stepping-Motor-2-5Nm-1-8Degre-3A-115mm-Nema-23-Stepper/447726912.html)
nema 23 3.1nm (http://www.ebay.co.uk/itm/4-Stepper-Motor-3-1Nm-Nema23-439oz-in-1yr-Warranty-CNC-Milling-Lathe-Conversion-/111158224887?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item19e18be7f7)

Clive S
29-09-2013, 10:18 PM
Well a lot of people on here seem to favour the nema 23 3.1nm from CNC4U as they are good value and seem to have passed the test of time. ..Clive

29-09-2013, 10:39 PM
Torque is related to current but holding torque is of little relevance for CNC use. More critical is winding inductance, the smaller the better and winding resistance, again the smaller the better. These determine the real torque available and how fast it drops off with speed. On that basis the smaller cnc4you motors are far far better. The ones on Aliexpress look like an older design and may represent over stock of something built for a specific customer.

30-09-2013, 04:06 PM
I agree with irving.
I've spent far too long in the past looking for low inductance motors from aliexpress. I'll be amazed if you can find any that beat the cnc4you ones.