Random change of direction of laser movement (X axis)


I need help with an laser engraver positioning and it’s device configuration. Actually i have problems with collisions and framing any object that i created at my workspace. I cant even directly detect when the core problem is.

Problem description

  1. Manually set posion of the laser at left-down corner (as a 0 position).
  2. Turn on the laser.
  3. Turn on the LightBurn application.
  4. Draw some recatangle at the middle of workspace.
  5. Set the option to use “Absolute Coords”.
  6. Try to “Frame” an Object.

And the mentioned problem is here. Sometimes the laser looks to be moved randomly at the X axis.

Laser moves to the rectangle origin postion and starts framing the object. I can’t see the pattern there, because sometimes framing is properly and sometimes a the next usage of “frame” option casuses wrong route of framing (change direction of X axis move). Sometimes even it moves the way that it hits the rails.

In this case it is like, the laser do framing and stops at the starting position (after properly done framing). Then starts another framing route where this try randomly change direction of moving.

Tested things:

The thing i saw here is problem with the X axis. It looks like this moves change direction of moving randomly. I tested it on the “Move” pannel.

  1. Manually set position 0 (down-left corner) and re-run laser.
  2. Click “get position”.
  3. Click “right arrow” once and the laser moves by 10mm right.
  4. Click “right arrow” again for the 5 times but the result is that te laser instead of moveing by 50mm to the right, the laser moves: left → right → left → right → left. As a result, the laser did not move at all on the x-axis.

The Y axis moves looks to be good and there is no problem with moving in that positions.

Console Logs:

Waiting for connection...
Grbl 1.1h ['$' for help]
Target buffer size found
Starting stream
[MSG:Pgm End]
Stream completed in 0:00
Starting stream
[MSG:Pgm End]
Stream completed in 0:00
Starting stream
[MSG:Pgm End]
Stream completed in 0:00
Starting stream
[MSG:Pgm End]
Stream completed in 0:00
Starting stream
[MSG:Pgm End]
Stream completed in 0:00
Starting stream
[MSG:Pgm End]
Stream completed in 0:00

Device Configuration

Command: $I

Target buffer size found

Command: $$


Command: $#


Command: ?


I have a grbl machine, but not the same as yours.

I don’t see anything that looks out of ordinary from the output. The only exception is the $23 which is the homing direction of each axes. This is usually 0, but since you have disabled homing, I don’t think it matters.

If possible, a video might help us with this. At this point I have no idea…


The controller is acting as if everything is fine.

First check the stepper motor for the X-axis. Does it more in the correction direction in your example of jogging right 5 times? I suspect it won’t. But if it does, check where in the chain from the stepper to the belts to the laser head where it might be missing steps.

If the stepper is not moving in the right direction double check your cable between the controller and the motor. Do you see any damage to the cable or the connectors? Make sure you are getting a proper connection and that the motor is plugged in correctly.

If you cannot see anything strange with the cable try swapping the connectors for X and Y motors. Be careful as you use the controls because they’ll have swapped but see if the problem follows the cable or stays on the same motor.

If the problem stays with the motor then likely the motor is bad. If it moves to the other stepper motor then the problem is either the controller or the cable.

To check if cable or controller try using the known good cable on the X port of the controller with the known good motor. If the problem persists then the problem is in the controller. If the problem is fixed then the problem is with the cable.


I used the tips from you to verify the problem. During the tests, it turned out that the controllers and cables themselves were fine, because after switching the places of the cables, the problem on the axis disappeared.

After identifying the correct operation of the controllers, I found the problem for me was caused by the USB cable (the connector to which the USB cable is plugged in).

Thanks a lot for your tips :slight_smile:

1 Like

Wow. USB cable? Such a very specific symptom for it to be a USB cable issue. Glad you figured it out.

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