X Axis Grinding

Ok guys, I’m losing my mind here. everything was fine, I’ve been using my mpcnc a lot. Everything was working amazingly well. Little background, when I first put it together I had one X motor not working. I’m using the ramps board with dual endstop firmware. I switched positions of the motors, meaning X1 and X2, and everything worked perfectly.

on repetier host I did change the travel feedrate from 4300 to 2100 as suggested. Now I’m in a world of problems and simply can’t figure it out. My Y and Z axis move just fine. I have checked continuity on all of my wiring, I have swapped X and Y on the board. The X Axis, one motor will move, but sounds like it’s skipping steps or is in chop mode. The second motor will move if I bump the feedrate movement to somewhere around 10000 but still makes a terrible grinding noise and doesn’t move quite right and seems to change direction on its own with no rhyme or reason.

I have reflashed the firmware twice, only changing steps per mm to half of what they come stock because I’ve already figured out that stock is double size. What else could it possibly be? Everything was working perfectly fine.

Edit: just switched X and Y, same motor is still doing the same exact behavior

Grinding is usually a wiring issue. Especially if it stays with the motors. Might have an intermittent pin in the harness.

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That’s my next step is to check through the wiring on that one motor. I also just ordered a 5 pack of replacement motors just in case.

Would that also cause it to change direction for no reason? I only have flags on it currently

It can.

The strangest part is that it didn’t start until I checked and unchecked “turn off extruder when finished”

The motors are usually very robust. I would strongly suggest checking the wiring along with the motors. The wires heading the motors fail quite often. The motors themselves, even the wiring in the motors, almost never fails.

Would checking continuity on each pin be enough?

It’s a start. You can have an intermittent connection when it moves as well. Sometimes the pins get pushed out of the little black connector piece.

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Alright, so it’s fixed up, my DuPont connector melted somehow, might have pushed it a little hard


Pull the wire off of the machine and check the full length. This could also be happening if there’s a crack in the wire and it’s shorting out.

Edit: and now I read your last statement :blush:

Well there’s your problem!


Well and truly understated :smiley:

I’d say this is more likely if it’s not pushed hard enough. I had a sketchy connection that felt loose and later found it melted. I presume it had poor contact and some resistance, which with the motor current turns into some dissipated power that’s not insignificant.

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