Hello,
I'm currently making a simple plotter and I'm using two stepper motors (NEMA17) with a GRBL shield and an Arduino uno, but I can't figure out how to select the proper power supply for this setup.
I have decided to use a 12-volt psu but still stuck in calculating the current rating. Another issue, I read that the current ratting for the NEMA17 is 1.7 Amps but I don't know if this is for both coils of the motors or each coil needs a 1.7 amp current?!!
Thanks in advance.
12V 5 Amp will be plenty. Which stepper motor drivers are on the shield? Have you set the stepper current limit on the drivers? The stated coil current (from the motor data sheet) is what you set the current to.
If you study the motor specs you will probably see that the 1.7amps corresponds to about 2.5volts for a total of 4.25 watts. Double that for two motors and add a margin gives you about 12 watts. A 12v 5 amp power supply will deliver about 60 watts. However there is no harm having an oversized power supply.
Just make sure to set the current limit on the stepper drivers to match your motor.
By the way, 1.7 amps may be a struggle for an A4988 unless you have a heat sink and a cooling fan. I think the DRV8825 drivers also fit the GRBL shield and they have a bit more capacity.
