Overheated and Print Stopped because of Fire

I’m not sure if I should post this here or not, I’m not sure if I have a problem yet or not.

I was engraving on 1/4th clear acrylic, which I’ve used this same material many times before without incident, but this time I got a overheated error and the gf stopped printing on its own. I got up to look at the print to see that there was a small fire around where the print head was and the acrylic had melted.

Now I’ve seen my share of little flames here and there, but this is the first fire I’ve seen. And it was still burning until I opened the lid and blew it out.

I’m only speculating here, but the only thing I can think of is that the print head must have stopped moving and was continuing to engrave the same spot until it got too hot and caught on fire. You can tell from the photos that the melted area is pretty large so it must have been there for more than 5 minutes or so.

I don’t have video of this… I wish I did. I always watch each cut/engrave at the start to ensure things are going as they should and this time was no exception. And then I usually leave it alone and check on it once in a while… but never more than 10 feet away at my desk. So I know the print or engrave started fine.

The print head was, and still is as I write this, very hot. Too hot to even hold by bare hands. Doesn’t look like anything melted on that. I notice blacken areas where the sensors are but those usually get dirty and can be cleaned, so hopefully this time is no different.

I also removed the lens and mirror from the print head and don’t see any issues with those either.

I’ll report back after I let things cool down for a few hours, and try to start the gf up again. I will do a simple cut to see how it goes.

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This is why you never, ever leave the GF running unattended, meaning if you can’t see the laser head moving, you aren’t watching closely enough. I would wait until Support gets back to you before doing anything.

The only time I will not be standing over the GF watching the head move, looking for flareups, is when I am engraving something that can’t catch fire, like slate. If the material is flammable, I am watching it the whole time, like a hawk.


Well I can see the print head moving from my desk… but that doesn’t mean I’m watching it 100% of the time during a 2 hour engrave. That’s not ever going to happen.

But I have now ran it… after a deep clean to ensure there is no smoke or burn marks anywhere… and it ran just fine. And I did watch the full 20 minute engrave this time.

While this is good news, but still not sure why it stopped in the first place. Perhaps it stopped because of over heating and for some reason the laser kept firing even though the print head stopped moving? Not sure. But again, seems to be running fine now.


If the head was too hot to hold, that would set off the normal overheating sensors. I have observed that the internal fan operating with insufficient movement alone can cause such positive feedback loops that rather than cooling the head it keeps on heating it more. that has happened perhaps twice in the past year when I paused the machine.

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If you would supply the date and time that the incident occurred, Support can check the logs and see what was happening at that time. That way, if you have an issue you can prevent a reoccurrence.


I’m so sorry to hear that you hit this snag while printing on your Glowforge. I appreciate you taking the time to outline the behavior you noticed while printing, and for sending over these photos.

I’ve extracted the log files from your Glowforge to review the print you noticed this behavior. Based on the logs, it does appear that the print failed due to the Printer Head being too hot. However, it does appear that after performing a deep cleaning, and checking all of the components from inside of your Glowforge, you were able to perform some additional prints. That’s great!

I’d like to double check a couple of things to make sure everything is correct. Could you send over a new photo of the bottom of your Printer Head, and any of the areas you cleaned? Sending a photo similar to the one below would be great:


Once we can review this image, we’ll send over the next best steps.

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As you can see, it cleaned off pretty well. I did an overall cleaning as well… which I normally do anyway. And I had cleaned it just before this print too… always only use the Zeiss wipes and sometimes the spray on the glass…

I know it get too hot… I had saw the error / warning message for that. What I want to know, if you can tell by the logs, is if when the print head stopped, did the laser keep firing? Or did everything stop because of the fire and the fire is what melted the acrylic? I just want to figure out what started the fire.

Thank you so much for the details. I’m looking into it now. As soon as I have more information I’ll update this thread.

There are a couple things we recently announced in latest improvements that I’d like to highlight:

In these sections:

Extreme temperature sensing

Improved sensor monitoring

This print was one of those cases where unusual readings of extremely high temperatures caused an alert, which paused the print.

Pausing the print stops both the laser and the motors, the same as when you pause manually.

I noticed that the print wasn’t using Proofgrade material or Proofgrade settings.

Since this problem is being seen on materials that were purchased from another company, we can’t offer support for prints that don’t come out as expected. Materials may vary widely from piece to piece, even if they’re created by the same manufacturer. I suggest posting for advice in the Beyond the Manual section of our community. Note that advice in this section is unsupported and is not reviewed by Glowforge.

Should this happen with a print on Proofgrade materials using Proofgrade settings, please let us know and we’ll help you right away!

I’m going to close this thread. If you have any other questions, please feel free to open another thread, or email us at support@glowforge.com.