K40 stops just a few seconds after I press start

Using Windows 10, Cohesion3d laserboard on a K40 with the most current version of lightburn. Once I press start, it starts just fine but runs for about 5 seconds then stops completely and it’s showing in lightburn that it has finished.
What could be causing this?

Might want to post what you are working with. The .lbrn file would probably ok, as that would give us your settings for the layers.

It sounds like the machine thinks it’s finished the job.

It’s just a basic 2 layer file. It also does the same thing on other files not just this one.

Ram Reunion-1.lbrn (299.5 KB)

Hi Donald, the file you uploaded is slightly different than your screen shot and has 3 layers. But given that the file looks good and the Gcode looks correct. Preview time is 7:mins 45 secs. Could it be a electrical noise problem, or long USB cable perhaps? that is causing the controller to stop?



I’ve used the same USB cable for years without a problem. But I did switch it out for a brand new cable. But it’s still doing the same thing. Not sure what you mean by electrical noise though. I’ve checked all connections and everything seems to be ok. It’s frustrating. I have an order to fill but will have to refund them at this point.

Hi, here’s my two cents.
I have a k40 with Smoothieware based controller and when the transfer mode was set to Bufferd I experienced the same: scan stopped after two lines or so.

Since I switched to Synchronous mode - all’s good.

I am not saying this is the solution for you cause many uses the Buffered mode which should be faster, but this mode does not work for me. so you can give it a try and see if you get different results.

By electrical noise I am talking about something switching that is generating a spike on the supply line to the controller. Possibly something in the laser itself or external. Others have found that loose ground connections can cause this type of fault.

You are a game saver Squid. I have no idea how that setting got changed. Thank you so much for your help.

:+1: You’re walcome.

It seems this is not LPC1769 nor LPC1768 related. Just FYI as Donald is using a Cohesion3D LPC1769 based and I am using SKR LPC 1768 based controller.

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