Arduino CNC shield, NEMA 17, 4988 drivers, steppers will not turn.

Other Hardware Motors, Mechanics, Power and CNC
1

Afternoon All,

I'm quite new to this but I have some experience with Arduino projects I have the following setup. I've been building a new laser cutter with all the frame / 3D prints completed and all looking good. I'm now moving onto the electronics. I've chosen the following equipment which is all new:

Genuine Arduino Uno.
CNC Shield V3.
12V power supply for CNC shield to power NEMA 17 motors.
2 x Nema 17 motors
2 x 4988 drivers (I have 2 x DRV8825 drivers too)

I've flashed the Arduino with GRBL 0.8, added the CNC shield, 4988 drivers and trimmed the pots correctly. I've checked the wiring on the NEMA 17 and identified both pairs. Powered the Arduino via the USB from a laptop and powered the CNC shield with 12V power.

Now the issue:
Once the USB is inserted and CNC shield powered the NEMA stepper will not turn by hand, tried adjusting the pots, swapping the 4 wire connector 180 degrees and still not right. I used Repetier host to send GCODE to test and nothing I seem to try will move this motor.

Open to ideas from the forum if anyone has any suggestions here.

Many Thanks

2

From the "command line" in Repetier, enter "$$" (without quotes) and copy and paste the response here. That should tell us about the grbl setup. If homing is enabled, the machine is locked until homing is completed successfully.

I don't have Repetier so I have to ask, is there a status indicator that tells if grbl is idle, or in an alarm state? Does Repetier have a grbl mode? Maybe Universal Gcode Sender(UGS), which is made for grbl. would be a better gcode sender for you.

3

I suggest you use this Simple Stepper Code to test that the motors work properly. You will need to select the appropriate I/O pins for each motor and because you are using the shield you may also need to use the enable pins for each driver.

Have you properly adjusted the current limit on the motor drivers?

If you are still having problems please post a link to the datasheet for your motors. Nema 17 just defines the size of the front face (1.7 inches)

...R
Stepper Motor Basics

4

If using Robin2's simple stepper code to test the motors (a good place to start) using a CNC shield, you will need to enable the steppers before they will work. The CNC shield holds the enable pin HIGH, disabling the motors, by default.

Add :

const byte enablePin = 8;  // pin 8 controls enable of all drivers on the CNC shield

to the pin declarations.

In setup() put:

pinMode(enablePin, OUTPUT);
digitalWrite(enablePin, LOW); // enable stepper drivers