Z-Axis motor inverted operation


I was running a test cut when the Z-Axis started to not work.

I first checked the V-Wheels if they was too tight but was ok. Then checked the belt tension and was ok. So I noticed that the motor pulley metal insert was really loose. I tightened them back.

Now, after a test cut, when the machine have finished the work it have not raised up the Z-Axis when it return to the home position ruining the work (but was a test and not really a problem).

But now the Z-Axis won’t work at all! I disassembled it because I thought the motor was screwed and noticed that the motor get inverted command: When I set up the machine for example, if I told to make 5 step down, the motor make 3 step down and 2 step up! (just an example)

All the other axis work nice and smooth! Any advice? I first thought about a wiring problem into the terminal block, but the green led on the G-Shield are all ok!


It really sounds like a loose wire on the Z-axis motor.

Do you mean that maybe some wire are touching each other?

Yes, either a short (wires touching) or one is loose and not making good contact.

On the terminal block or G-Shield? Or better to check both?

Check them all, it could be anywhere.

Ok, thanks!

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Do I need to check only the Z-Axis terminal block block or ALL of them? (I’ll check it tomorrow, too late now)

Since the issue was with the z-axis, That one needs to be checked…nothing wrong with going through them all just to verify. I check all of mine on a regular basis just to make sure.

That’s a nice advice. I’ll take advantage and make the motor current calibration, seems a good timing for check it

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Luckily it was just a red cable into the Z Axis terminal block of the control unit. Damn vibration.

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@ErikJenkins Sorry to bother again, but seem that the machine is sort of losing steps at some point of the cutting. And it goes totally out of path. Any idea? I was cutting just a 0,5mm depth! It loose steps/going out of path on the left side of the machine when cutting a small curves.

Sounds like you need to adjust the motor current…read this thread:

I thought about that too, but then I randomly started to cut some circle of various dimension and depht, and they are pretty perfect.

Maybe could be a drawing error…but I guess set the potentiometer is something that I need to do sooner or later

Edit: I had to tighten all pulley thread and belt tension too.

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