K40 Laser can test fire but isn't firing when trying to engrave/cut

[lasersarefun (M)]

Hello there!

I have a K40 upgraded to the cohesion board running lightburn. I’ve downloaded the omtech material test file and am trying to run it, but it just never actually fires the laser. It does frame and move around correctly but doesn’t fire. I’ve checked the following so far but looking to see what else I’m missing:

• If I do a test fire from the control panel it works fine once I dial it up past 13% power on the display there.
• There are no interlocks (yet), nor is there a water supply sensor so those aren’t in the mix at the moment (those were the issues in other threads).
• The file in lightburn has what appear to be proper settings for speed and power for the various cuts in the test file.

My assumption is that lightburn can increase or decrease the power of the laser and I don’t need to set the power level to something higher…

What else should I try? Thanks in advance!

[donkjr (Don Kleinschnitz Jr.)]

So I am clear:

• Everything work as normal at currents above 13 ma?

Questions/requests:

1. Post a picture of your control panel.
2. Post a picture of your LPS with the connectors showing
3. Post a picture of your tube while firing
4. Post a picture of the burn from the output of the laser, before the 1st mirror
5. Did anything change or has this always worked this way?
6. Did the machine behave differently before you upgraded to the C3D?

[lasersarefun (M)]

Hi Don, thanks for responding, here is what you requested:

1. Here’s the control panel top and underneath
   

   
   
   
   

2. Here’s the PS and connectors:
   

   
   
   
   

3. For a picture of the tube I couldn’t really capture that with one hand so I shot a quick video instead: k40 firing only when testing - YouTube

4. Not sure what you’re asking for here?

5&6. I’m borrowing the laser from a friend of a friend who said it worked fine in the past, but I’ve since upgraded the board to C3D and am trying to do the first burn since then.

Also here’s a shot of the lightburn file to see if it looks right to you guys, I wouldn’t know any better yet:

To me it shows its trying to cut at 40%, so my assumption is it raises the machine power to 40 to do so, rather then the 13 I currently have it at, but perhaps that is an incorrect assumption.

[lasersarefun (M)]

Sorry I missed your question about the power. I have the machine set to 13% which is showing at like 3 or 4 ma. If it’s below that it won’t test fire, if its above it will. I haven’t tried raising the power level to see if lightburn works if the machine power is higher because I assume lightburn can raise the power itself.

I’m new and don’t want to break anything so taking baby steps. I could try setting the machine power higher and then trying to run the test file in lightburn maybe?

[lasersarefun (M)]

Update: I tried raising the machine’s power to 30% on the control panel and that started making the laser fire when running the test file, so my assumption about lightburn moving the laser % up and down by itself was incorrect. It appears I need to set my laser power independent of lightburn?

[lasersarefun (M)]

I found a number of other threads explaining K40 power settings on the machine, which are different from the settings in a Lightburn file, so I’m good to go now. I learned each machine is a little different but that I should set my test fire level so it hits around 12-15ma, then a 50% lightburn command should hit around 6-7ma, etc.

Thanks!

[mcdanlj (Michael K Johnson)]

Right, the front panel is setting the maximum, and then the number sent from Lightburn is percent of that maximum.