New LaserBoard install losing X,Y during burn

Machine: K40 - SunCoo 40W Red

Board: LaserBoard

Firmware: “I have a new board and I’m using whatever it came with”

Problem/ Question: New LaserBoard seemed to install okay, but during testing, it seems to be losing its X,Y location while active. The machine homes okay and seeks to locations without issue in manual movement.

Burning something that went okay with the chinese board, over halfway through the design, the machine clunks and its X,Y is no longer true. This results in part of the burn ending up in the wrong location.

After an unsuccessful burn, the laser head has the wrong X,Y location and must be re-homed to zero itself out again.

Image as it appears in LightBurn:

Please post photos of your board, wiring and if possible, a video of how it’s behaving. You can now add more than one photo.

What speed are you doing this? Have you tried slowing your line speed? If you go to fast, the motors can miss steps and jump around.

Would you mind sharing the file so I can test it on my machine? I promise to delete it after testing.

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I second what Jamie has said about speeds. If you are doing a vector engrave and the speeds are too high as it changes directions it can lose steps.


This was initially moving at 40mm/s, and I have reduced to 20mm/s. Still getting the same results. This also happens when painting a raster image as well.

In the video, you can hear the noise at about 2:28, and the rest of the image is drawn down too far.

After watching the video it appears as though your cut speeds are fine. You may have to check your belt tension and also make sure your acceleration is not set too high, as it looks like it is having the issue moving from one cut to the next.
Also depending on how old the machine is you may want to carefully look at the belts to make sure no teth are missing or worn low, rare but it happens.

Lowered the acceleration from 2500 to 1500, seems to be working much better now. It’s a new machine, and I didn’t see anything wrong with the belts, but I’ll recheck anyway and check the tensioning.

Thanks for the help!

The Y axis on these machines are lacking. I was having this problem and had to up my current slightly on the Y which took care of the problem.

We used an interesting combination of values in the stock config file - the axes are set to move quite fast, while the motor currents are set on the low side. You can safely increase the motor currents up to the maximum of 1.2 amps, and you may also want to decrease the seek rate if you find that the skips are while the head is traveling in between cuts.

After further testing, and finding more issues, I lowered the acceleration to 500. The digipot_max_current was already set to 1.2 (never changed that). Should I modify any of the other values?

I’ve continued to lower the speed, and am still having issues with trying to draw a raster at 250mm/s - below the initial 320 the chinese board was set to and used successfully.

At this point, my next step is to pull the LaserBoard back out and see if I can reproduce anything with the chinese board in place.

config.txt (28.4 KB)

The digipot amps is not what you need to adjust. he was referring to the stepper driver current.

alpha_current 0.4 # X stepper motor current

beta_current 0.6 # Y stepper motor current

These are from your current config.txt
As well it was mentioned you way need to lower your seek rate, yours is currently.

default_seek_rate 24000 # Default rate ( mm/minute ) for G0 moves

I have modified some values:

default_seek_rate 10000
x_axis_max_speed 10000
y_axis_max_speed 10000
z_axis_max_speed 10000
alpha_current 1.2
alpha_max_rate 10000.0
beta_current 1.2
beta_max_rate 10000.0

This has had little to no effect, still seeing issues like this (x-axis position issue here):

Assuming there’s something I’ve missed, is there anything else I should modify in the config?

config.txt (28.4 KB)

If you try to do a burn and move it to another location on the bed does it mess up in the same place on the bed or the file?

Currently trying another burn with the exact same settings, and it has not messed up at the same spot so far.

Looks like it did not error til much later in the burn this time, all settings exactly the same. I have been resetting the power and re-homing often during my testing, including before this burn.

Continued testing, smaller version that started in a different origin. Three tests, three errors in different spots. (different size shift too) Did a fourth with a different laptop to rule that out. (Linux vs Windows)

1.2 on the stock motor is a bit much. I didn’t need to go any higher than 0.900 to straighten mine out.

Something I noticed, but first wrote off to noise from the water pump - after my board initializes (and USB plugged into the computer) you can hear a noise coming from the stepper motors. It sounds like something between air hissing and water circulating. This noise is not produced when using the original board.

You can hear it in this video at about 0:07 after the USB cable is plugged in and it re-homes the head.

Is this normal? Are my steppers unhappy for some reason?

edit: this occurs both at the original, and at the new 1.2 current settings

The hiss is explained here, however I would not recommend changing those settings yet: LaserBoard Stepper Motor Noise and Stepper Driver Modes

Please post a video of the job being run so I can see what the issue looks like. Please also try jogging the head back and forth with LightBurn and show a video of that.

Here some some homing/rehoming, x/y movement, a simulated vector burn, and a simulated raster burn.