SKR PRO / Laser / LightBurn issues

Finally I was able to hook up the laser to my Lowrider III with an SKR Pro Board, first I struggled with the connections to the board, once I hooked it up to the right way, and all smoke of burned wood was gone from the living room :smiley:
I decided to put the machine back in the garage, but for the moment I’m having difficulty’s getting Lightburn to connect to my Lowrider and generating proper G-Code.

When I let Lightburn detect my machine it comes up with GRBL, I’ve read that the detection doesn’t work and I have to set it up manually.
However, for some reason I’m not able to figure out the right settings.

Has anyone got a working configuration file which they are willing to upload so I can try these settings?

Problems I find now are;
Lightburn does not recognize the SKR Pro board as Marlin ( only GRBL)
Created G-Code does not work as supposed (laser turns on and off every line)
Laser does not get to full power
barely able to cut trough paper :frowning:

Any help is much appreciated.

Lightburn machine settings;

Current Generated code;

Isn’t the SKR running Marlin, not GRBL? You can change that in Lightburn. I don’t remember where to change it, but i’ll look when I get home.

I think you have to manually set it up as a Marlin Machine( going from memory). I’d set up a new device as a Marlin device. I believe it was a selection you could choose.

I Used this;


the only thing that’s not correct is the machine size, I kept it to 250x250 but don’t think that would be the issue here.

Your Lightburn settings look fine. They are very similar to what I use. There are some things to take a look at here:

  • What is the optical power of your laser module? Given the feedrate of 6000mm/min and 40% power, I would not expect a 10W optical module to do much beyond cutting paper.

  • The 6000mm/min feedrate is beyond the default minimum (300mm/s) feedrate in the V1 maintained versions of the Marlin firmware. Did you modify the maximum feedrate in the firmware? It can be done with g-code. Personally, I have the g-code command in my Lightburn start code that significantly ups the maximum feedrate. Note I don’t include an M500 to save this setting. That way, Marlin will default back to the slower feedrate when using the machine for CNC routing.

  • Have you focused your laser? Focusing makes a huge difference in cutting performance. Also, air assist makes a noticeable difference in cutting performance.

I think the settings look OK, but I do not know what the mas S factor is set to within the firmware.

I see there that the 40% power setting gets S102 power factor.

I have mine set to max power at 1000, which would give max power (S255) a bit over 25% duty cycle. 102 would be ~10% power, or about 1W optical power. I find my Neje 10W laser able to engrave wood fairly easily, even cut.

You can see in the lower right where the max “S factor” is set to 255 here. If max power does not do the same as hitting the test button, try changing that to 1000. (Then yoh see jf it’s different at 26% and at 75%, if the firmware scales from 0-255, both would be the same at 100% power.)

He has an SKR Pro running Marlin, so the S factor will match the PWM of 255. My S factor for my Rambo board is 255. My alternate laser machine is GRBL and has an S factor of 1000. If he is really moving at 6000mm/min and 40% power with a 10W machine, then he cannot expect more than cutting paper.

I Use a 10W laser, it is the;

ZBAITU C80-EAIR 10W Laser Module with Air Assist

the Feedrate shown in Lightburn is the default of Lightburn.
I did not change it so far, because I was still busy trying to get the communication set up correctly.
So far I am only to communicate to the board using GRBL setup. with Marlin it doesn’t work.

Looking in the V1 Marlin settings of my Lowrider it has been set so a max X and Y speed of 50 mm/s and the max Z is set to 15 mm/s

But these settings should not involve the communication from lightburn to the board is my guess.

Also when I type in a command there’s no response.

The g-code you posted above is Marlin code. I’m almost certain it will run on my MPCNC as is. If you want to attach the file to a post, I’ll be glad to run it and verify. Note you might try saving the g-code to a file and running it from an SD card on your SKR Pro. I know there have been some recent changes in the V1 SKR Pro firmware that require SD card jobs use the SD slot on the SKR Pro, and not the one on the display.

Note that all the settings that are the typical sources of trouble are correct in your screen grabs above.