Nema 42 and its driver

I'm trying to use the Nema 42 with an 8A current. The driver that goes with it offers a max peak current of 7.2 and an RMS current of 6.0. It also has 400 steps/rev as its largest step, whereas the motor's is 200 steps/rev for full stepping. I had read that half stepping required two coils to be used simultaneously and that would require double the current. Is that true? It is running EXTREMELY slow and we were hoping for at least 600 RPM. Is that just way too fat for this motor? I've been looking at other drivers and I can't find any that go up any higher in output current. I WAS able to find some that offered full steps (200 steps/rev). Would that help? Thanks!


Nema 42 (spec sheet in pics)

int driverDIR34 = 2;
int driverPUL34 = 3;
int driverDIR42 = 6;
int driverPUL42 = 7;

int pd = 500;
boolean setdir = LOW;

void setup() {
  pinMode(driverDIR34, OUTPUT);
  pinMode(driverPUL34, OUTPUT);
  pinMode(driverDIR42, OUTPUT);
  pinMode(driverPUL42, OUTPUT);
  digitalWrite(driverDIR34, setdir);
  digitalWrite(driverDIR42, setdir);

void loop() {
 digitalWrite(driverPUL34, HIGH);
 digitalWrite(driverPUL42, HIGH);
 digitalWrite(driverPUL34, LOW);
 digitalWrite(driverPUL42, LOW);

Without links to the datasheet for the motor and for the stepper motor driver I can't see how we can help.

Also post the program you have been trying.

Stepper Motor Basics
Simple Stepper Code

Your stepper motor should possible be driven with up to 40+ volts. what are you using?


Edited with these inclusions. Thank you.

This is the driver we're using. It only goes up to 6.0 Amps (RMS) and has a minimum of 400 pulses/rev.

Start with a much slower step speed - perhaps 4 steps per second. That's a big heavy motor and it will need to be accelerated to higher speeds.

Rather than this style of code

digitalWrite(driverPUL42, HIGH);
 digitalWrite(driverPUL42, LOW);

this makes the logic clearer

digitalWrite(driverPUL42, HIGH);
 delayMicroseconds(10);    // a short pulse is usually sufficient
 digitalWrite(driverPUL42, LOW);

In your example the intervalBetweenSteps is the variable you have called pd



Thank you so much, I will try this.

Yes, speed ramping is absolutely essential with any stepper larger than a grape, mass cannot instantly accelerate.

Higher supply voltages are needed for higher speeds. That NEMA42 motor has a lot of winding inductance
at 16mH, so needs a high supply voltage to spin fast. Its designed for industrial controllers able to run at 80V or more I suspect. Its 1 ohm and 8 amps, so it has a dissipation of at least 64W, requiring a minimum of about 100W of supply, probably more. 48V at 2.5A might be a possible power source, assuming the driver can handle the voltage. More than that and you are in the high voltage realm, so safety rules change.

Stepper drivers act as power converters, so the current from the supply can be a lot less than the winding