Hi,
another fairly simple test is to install an ammeter in one wire of the stepper.
The stepper driver will be using a sort of pulse width modulation technique to regulate the current. If the full voltage of the DC supply were hooked to the stepper
the current would be so great that the motor would be destroyed in short order. For the purposes of this test a good-old rugged analogue meter is best.
Note also that the current in any given wire will reverse direction with each step, so your meter will try to read backwards, provided the current is not too
high relative to the rating of the meter it will probably withstand being driven backwards.
Another couple of points should be made so that you can be sure that your measurement is accurate.
The first is that with microstepping, and just about all drives for CNC use it, the current builds up to its peak through each intervening microstep to its maximum
that occurs on the motors natural fullstep. I would recommend therefore to switch microstepping off for this measurement, that will means that any current
you measure will be the maximum the drive is capable of or configured for.
The second issue that it is common for stepper drives to reduce the current delivered to the stepper if the drive is sitting at idle for any length of time. So if
the stepper drives to a point and then sits there, still with its maximum current its going to get warm so if its stationary for more than a second or so the drive will
reduce its current by half to save the stepper from getting to hot. For this measurement you want to disable that current reduction feature so that you will
at all times get maximum current and therefore a realistic appreciation of the motor current.
Now you have to decide does the measured motor current correspond to the manufacturers rated current?
Craig