How to change the rotation of the stepper motor to be unidirectional in grbl

I made a CNC machine with 2 stepper motors for the y axis like this picture.

but both are moving in opposite directions, how do you get the motor to move in one direction. I’m using grbl v0.8

You must reverse the wire order on one of the motors.

As an example, if the left motor wires are connected to the driver in this order…

Red, Yellow, Orange, Blue

The right motor should be wired…

Blue, Orange, Yellow, Red

Since the motors are facing each other, and they are technically turning the same direction, you need to reverse the direction of one of them. Most easily the one going the wrong direction of the movement you specified :wink:

You might want to tighten those belts. They look pretty loose around the pulleys. Also, just a word of warning, I see white belts, that means those are most likely steel reinforced. Since they are bending over such a small diameter drive pulley, the steel cables will break over a relatively short time and you’ll have stretching issues. I’d recommend getting the regular black colored, nylon reinforced belts.


Hi @Strider_Matic
thankyou for the response
after I tried according to your answer, my CNC runs according to what I want. about the steel belt thanks for the advice, maybe I’ll consider replacing it with the nylon belt you mean.


No problem! Welcome to the fun!