I always wanted to have a CNC to make PCB quickly at home.

Finally, I got a 7x7 kit from zentools recently and put it together. I attached a battery powered screw driver to 2nd shaft of the stepper and moved the each axis all the way back and forward before wiring. All 3 axis moves smoothly, I can turn the steppers even by hand. Every piece works smoothly, no mechanical jam.

I decided to use GRBL as controller software. Tested the software without the shield or stepper (qv: Testing GRBL in Arduino Board without the steppers) I use Universal Gcode Sender to communicate with GRBL.

I got an Arduino CNC Shield for Arduino UNO, put it together, attached to Arduino UNO, re-tested GRBL, it worked.

I used Reprep's Stepper wiring article to connect stepper to the driver, wired 1 stepper to the stepper driver (X axis). Powered the shield with 20V 17.5Amp (350W) DC Regulated Power supply. (It was the power adaptor for an old 17" notebook. Notebook died, I kept the adaptor)

When the move 5 steps command (G1 X5) was sent, stepper makes a small move in the direction and then makes a grinding noise. (Can be seen on Youtube)

I tried switching 1st pair's cables, using another stepper driver (3 drivers), turning the potentiometer to increase the current, but still no luck.

I attached 2 photos of the cnc and the controller and controller unit.

I tried everything I can think of, any suggestions?

CNC Controller (the DC adapter at the bottom)


1 Answer 1


After reviewing the Polulu Stepper Driver manual, I realized I was wiring stepper wires in wrong order.

The controller pin labels are: 1A, 1B, 2A, 2B. The controller card's manual was saying 'use letters as pair' but it suppose to say 'use numbers as pair'.

Everything works perfectly after correcting the wires.


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