[TEK73]

Hi

I'm looking for a stepper motor that have high torque as well as the option to have quite high rpm.
During my search I have found what seems to be two different "types" of motors. Or it might be that their specs are presented differently, and that is why I'm writing this post.

Stepper 1: http://www.ebay.com/itm/271436920030?ssPageName=STRK:MEWAX:IT&_trksid=p398 4.m1423.l2649
1000RPM Rotary Speed 1.7A 4.5kg.cm Torque 4 Wire Stepper Stepping Motors

Stepper 2: http://www.ebay.com/itm/CNC-Nema17-Hybrid-Stepper-Motor-2-Phase-48mm-4-Lead-1-8Degree-2-5A-/321134741362?pt=LH_DefaultDomain_0&hash=item4ac51f 4772
CNC Nema17 Hybrid Stepper Motor 2-Phase 48mm 4-Lead 1.8Degree 2.5A

Stepper 3: http://www.ebay.com/itm/NEMA-23-Stepper-Motor-12-6Kgcm-1-8Degre-4Leads-56mm-57BYGH56-401A/251301932447?_trksid=p2045573.c100033.m2042&_trkpa rms=aid%3D111000%26algo%3DREC.RVI%26ao%3D1%26asc%3 D22042%26meid%3D6178603913913735288%26pid%3D100033 %26prg%3D9536%26rk%3D2%26rkt%3D4%26sd%3D3212963116 85
NEMA 23 Stepper Motor 12.6Kgcm 1.8Degre 4Leads 56mm 57BYGH56-401A


The first stepper has a voltage rating from 12-40V
The second has a voltage rating of 3.1V (from table in description section)
The third stepper does not have a voltage rating at all, but have the absolute highest torque.

Is there any way to - from the given information on stepper 2 and 3 - to understand what rpm these two steppers will be able to run up to?

[ger21]

No.
A steppers torque will vary with rpm and voltage.
You need to calculate the torque you'll need at the maximum rpm you'll need. You also need to allow for the additional torque to accelerate the load.

The only way to know how much torque a stepper will have at a given rpm is to look at a manufacturers torque curve chart for that motor. This will tell you how much torque it will have at a given rpm, running at a specific voltage.

[TEK73]

Hmmm

So, if I understand you correctly, any given voltage has little or no value in regards to understand the rpm for these motors?
Also, the rated torque, for example of 12.6kgcm has little or no value as it is not stated what rpm that torque is given at?

And I assume that no one has a good idea about where to find these curves?
So how the heck do you go about to find the correct motor?

[neilw20]

Torque proportional to current.
Speed proportional to voltage, but as the speed goes up the frequency goes up and because windings have inductance, which resists a change in current, in a given time, extra initial voltage is required to achieve the desired current in the required time,
so back to post #2 and the manufacturers spec sheet Try googling the part numbers is a good starting point.