Stepper Motor current setting

Hello, I am sorry if the question seems stupid but i am working for the first time with stepper Motors and i may use some help.
I am running here a stepper Motor Nema 23 with arduino and the following specification in the pictures. with 24 V power supply and an DM542T driver. as i know the 4.2 A isn't the current i have to deliver to my motor to get the best torque because this current is per winding, it has to be 1.4*4.2 A = almost 6A, am I right?
additionally i am running the Motor with 400 steps/revolution instead of 200 steps/rev, how could i change the current so i can deliver the same torque as in full step mode, because in my driver it can be only set to higher than 400 steps/rev, in some forum it's mentioned that i can increase the current with the factor 1.4 once again.

The max current for the stepper motor should never be exceeded. Running at max current and single step You can't reach the same torque in double step, or any multistep.
Using the maximum voltage of the driver will contribute to best possible torque.

No, the rated current is the maximum current for one winding while the other winding carries no current. If both windings are active the sum of the squares of the two currents should be equal or less to the square of the rated current (quadrature drive).

Thus with full steps a 4.2A setting will send ~3A to both windings. If you look at datasheets for stepper driver chips they will show you this in detail for each microstepping ratio.

The upshot is that the power consumption is basically constant for a stepper (without mechanical load and at low speed)

The rated current is usually a thermal limit (in older alnico magnet steppers it was sometimes a hard limit to avoid demagnetizing the motor!!)

this was very helpful. Thank you

so i should stay with my 4.2 A and 24 V and if I want to get higher Torque i can can try to change the driver and use a one with 200 steps/rev. ?

this was very helpful. Thank you
this is what i thought but i got confused while i was searching for my project. so if i want higher toque i should go for less steps/rev?

your explanation, answered my question actually because i noticed heating in the Motor and Driver whenever i use it for longer than 20 - 30 min. is it normal?
1- should i try less current, like 3.76 A for example?
2- would i face the same problem if i increase the voltage to 36 V but decreased the current to 3.76 A?

in some PDF about stepper motor i saw few trade off between Torque/ current/ voltage as following:


Single step gives the highest torque.
Use the current needed for the job.
Running at maximum things do get warm.
Note that steppers still use full current even if they don't run. Powering down, disabling driver outputs, is one way to lower the heating. Note that there's no holding torque then.

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Thank you, i appreciate your help

But the least practical torque, as resonance is nearly always the mechanism of failure (miss-stepping).

x8 to x16 microstepping is normally the place to start for driving a stepper to keep resonance under control. Single steps are incredible noisy and create severe vibration, not pleasant.


Tom... :smiley: :+1: :coffee: :australia:

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