Loss steps in the X and Y axes

Mostly Printed CNC - MPCNC Troubleshooting
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Hello, I have been a few weeks with the finished machine and I am doing tests, but in each and every one of them, both the X and Y axes change their trajectory randomly. After restarting the system and executing the Gcode again, the machine makes the correct path but after a while it loses steps again. I leave some images and a video in which it looks like when the work is finished, it does not return to the original origin, but to a 10mm offset origin

WhatsApp Image 2021-01-03 at 21.51.27
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In this image you can see how the holes are not centered in the piece

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In this image you can see perfectly the moment in which I began to lose the steps in the area below

InkedWhatsApp Image 2021-01-03 at 21.50.44 (1)_LI
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Loss steps when return to home

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Some causes of lost steps

  • Grub screws on a pully not tight enough
  • Use of the wrong belts (don’t use steel core)
  • Too aggressive with depth of cut and/or feedrate
  • Steppers wired in parallel in a serial configuration
  • Low current setting on the stepper drivers
  • Intermittent wiring issues to a stepper

The grub screws are the #1 reason. Note that sometimes the issue is that Z is losing steps, causing larger depth of cuts than is programmed.

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Hello Robert,
thank you very much for your Reply to the post. I have a similar issue. My machine is loosing steps too…but its kind of worse because the X and Y axis are also jerking.
Can you please explain what its about wiring issues?

I think that could be my problem.

Thank you very much.

Greetings
Mr Braun

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Hi Alexander. There are a number of both mechanical and electrical issues that can cause jerking. If you can link to a video with sound of the machine showing the problem, we can make an educated guess about the source of your issue.

I’m not sure which wiring issue you are referring to. If you only have three stepper drivers on the control board, then the two pairs of steppers should be wired in series. Very few machines these days are built with only three stepper drivers. The result of parallel wiring will be steppers that have far less torque.

For intermittent wiring issue, there will be some connection that is broken intermittently. Usually this happens at a connector. Often the problem will only occur during one part of the range of motion for the axes as a particular connector or section of wiring is flexed in a certain way. The fact that you hare having the problem on both the X and Y is an indication that your problem is not and intermittent wiring issue.

As well as a video, if you could describe your electronics and provide a photo of the connections?