Tool movement stopping while laser still on

Hi there,
I’m completely new to laser engraving. Just set up my Snapmaker for laser and taking the first steps. One scary thing happened today. I started a print via USB with Lightburn and then left the room. The movement of the laser stopped, but the laser was still on power, burning a hole in the print material!
As far as I understand, it happened after finishing the first layer. It seems, as if the machine traveled to the origin of the second layer and then stopped moving by still engraving.
Looking at the preview everything seemed fine.


A friend from the Snapmaker forum wrote that to me:

My guess is Lightburn is not honoring the serial buffer being full, and just sending commands anyways. But the controller isn’t receiving them. So Lightburn thinks it sent the whole program, but the controller hasn’t heard all of it. Then the controller plays through the buffer, and then the buffer ends, usually where a cut ends - and there’s no M05 in the queue to shut the laser off.

Seems a possible cause?!

Buffer size in Snapmakers version of Marlin is 128 characters.

Hi @FlyByWire, the support to Snapmaker is not robust jet.
Nevertheless, according to another user, some issues should be solved in the next software update. Have a look to this post

I’ve the same problem you mention in my SM2 as well, so finger crossed.

BR. Gianluca

The solution is here:

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