Z stepper is running in only one direction

Mostly Printed CNC - MPCNC Troubleshooting
1

Hi,
I’m just building my first primo, I’m absolute beginner!
It already run, but now, after I cleaned the wiring, Z is running in only one direction, no matter if I click + or -!
I plugged Z to Y, and it is working fine, so wiring seems to be ok.
I used a different driver for Z, but its the same.
Anyone any suggests?
Thanks, Ole
Arduino UNO w.CNC shield, GRBL, UGS (Mac), Nema17 +DRV8825

2

Double-check the wiring. I’ll bet there’s a missing connection on the Z motor.

3

But when I put the Z plug at Y plug it is working!?

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4

Then double check the Z pins on the board are good, and see if one of the wires or pins on the connection gets turned differently when on the Z pins.

I’ve had motor connections that looked okay but the pin on the connector was partly crimped on the insulation rather than on the conductor, so just a little tweak in direction would cause troubles.

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5

The drivers use a pin to determine direction. The dir pin. There is probably an issue with the driver, or the cnc shield, uno, or firmware on selection. Doesn’t really narrow it down, does it? :slight_smile:

You could try to carefully use a voltmeter to see the state of dir. Just don’t short anything. You can also try saying it the driver.

6

That is also a symptom of the endstop being triggered. At that point it only moves away from home.

7

Thanks to all! :slightly_smiling_face:
I tried and tried and at the end I used a new Arduino board (borrowed from my son) and now it is working!

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8

Now I used setup wizard and did calibration of step parameter. All works fine so far, but when I start test crown, it moves a few mm ant the it run to the end and the pulley is rattling on the belt.
I guess I have to set a home point, like I used to do on my 3D printer? But how to do on a cnc?
I have no end switches, do I need some?

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9

No that isn’t right. If you use my file there is no homing involved. I suggest verifying the movements. X+ is Right, make sure 50mm is 50mm, Y+ is away from you, and Z+ is up away from the surface.

The test crown should move down a half a mm and then start drawing. No homing.