Y axis only moves forward

After re the g shield and checking all connectors after my machine locked up. My Y Axis only moves forward? My Z Axis no longer moves, and my X Axis just jumps? I have tightened my belts hoping that would solve the problem NO DICE. I reflashed grbl thinking that would be the next step maybe its just a problem of communication. Next I disconnected my limit switches to simply the problem in the off chance there was a conflict. At this point I am thinking my nema motor is fried or damaged and that wouldn’t make any sense. If you have any suggestions please reply

I might try removing the gshield and Arduino from the case, disconnect and reconnect them and leave them outside the case (on a non-conductive surface). Then you could remove your belts from the pulleys, and just check that each motor spins the correct way when you jog it.

If you have one axis (like your Y) and one that doesn’t (like your Z), try connecting the Z motor to the Y portion of your shield and see if it works then. Hopefully this will help you track down the source of the problem. Good luck!

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I agree with @PeterJames this sounds like you have a bad connection(s) somewhere.

The process he outlined will help locate the source of the problem.

Quite the opposite. Tested all motors they work, my belts keep loosening and now I’ll ask what trick is used to stop this I followed the instructions to the letter yet my belts get loose after one movement. Would like to be able to mill my first piece before my weekends up

Have you unplugged any stepper motors with power to the system. If you have you may of fried your stepper drivers.


If your belts are slipping, check this thread for some tips:

You’ll want to use a zip-tie, some electrical tape, or some heatshrink to keep the teeth engaged on the looped-back portion of the belt.

Continuing the discussion from [Resolved] Belt not tightening, just slips: