Y Axis Grinding

Hey folks - Ordered the MPCNC kit from the store here, everything was working well enough. Couple of test cuts went well. Now I’m having an issue that I can’t explain. Any movement on the Y-Axis of the Mini Rambo results in angry “grinding” sounds from both motors. Moving the connector from the Y-Axis to the X-Axis on the board and attempting to move works fine. Link to a video of what’s going on is below.

Kit I ordered - https://shop.v1engineering.com/collections/parts/products/mostly-printed-cnc-parts-bundle - 6A MiniRambo

Video of my odd grinding noise - https://youtu.be/7p0Vo2kC8rA

The face that the two Y-axis motors turn correctly while on the X-Axis connector, but not on the Y-Axis connector makes me think it’s the board. The X-Axis motors exhibit the same behavior on the Y-Axis connector. Anyone have some advice for me?



Sounds like a loose connection, maybe try slightly bending the pins in slightly opposite directions for a more positive contact.

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Just gave that a try, and wasn’t able to notice any difference.

Recheck the pins. Sometimes they get pushed out of the connectors. That’s the exact sound steppers make when one coil isn’t firing.

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I tested continuity from the solder joints on the mini Rambo Y Connector through to the connector on each Y-axis motor, and then between the two motors. No issues found. Those the pins your referring to?

I was referring to the stepper wiring harness, but sounds like you checked the whole kit and caboodle. What happens if you connect the y steppers to the x port on the rambo?

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It works correctly if I connect Y Steppers to the X Port.

X Steppers also exhibit same failure connected to Y Port.

So you know it is not the steppers or the ports. That just leaves the wiring. Time to double and triple check them.

To summarize,

  1. Everything was working, but now it is not.
  2. X wires & motors connected to X port, Y wires & motors connected to Y port - X moves fine, Y grinds
  3. Y wires & motors connected to X port, X wires & motors connected to Y port - Y moves fine, X grinds
Just to be certain, have you checked the fuses on the Rambo?

Pretty sure if it was a fuse it wouldn’t move at all.

I was wondering if there was a higher resistance on the fuse or power to the Y stepper leading to a detrimental voltage drop. Just a thought before diving into troubleshooting the board.

If you can’t figure it out you can reassign the bad axis to the open driver (in the pins file for your board). I single failed coil on these boards is unlikely but when wired in series you always have a spare.

Check the solder joint and see if there is insufficient solder on the legs of the connector or a solder bridge. Also, try reloading firmware, maybe a value got changed

Hi everyone

So I have the same issue but on the Z axis (grinding) X and Y work well with the same settings. I tried everything in this post I swapped the wiring and motor from the X axis with no change. Still grinds on the Z even when the motor runs free.

It all points to the board… or some mystery setting in Marlin (I’m stuck here)

Need help


Piotr, you should start a new thread and describe in detail you hardware and electronics, and pictures are a very good option for faster help.