Glowforge setting things on fire

Hello. Lately I’ve been having a problem where the Glowforge sets materials on fire. I have used the proof grade materials which I bought from the Glowforge website and other acrylics which I bought from Canal Plastics. These materials were fine until one day they started to make flames. Everything makes flames, it doesn’t matter what material it is. I have cleaned the air assist fan and wiped the Glowforge down. Not sure what is causing this, but now it is not cutting all the way through with the PG settings. Help!

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That’s almost 100% of the time a cleaning problem. There is significantly more steps than the “air assist fan and wiped the Glowforge down”. Visit and follow the cleaning instructions carefully and you’ll find it clears up a host of problems :slight_smile:


It is probably a fan that needs better cleaning or a file with detail that is too small. Perhaps you can post a video. Obviously, watch your machine closely and lift the lid immediately if there is flame.

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If your non-PG plastic has brown masking, that stuff has wax in the adhesive. Even a perfectly clean Glowforge will create occasional flames when cutting that stuff, which can be dangerous. If you want to be safe, remove the masking it came with, and either add your own paper masking or use a thin layer of dawn dish soap as masking.

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One thing often missed is when the lenses are cleaned the main lens is not cup side up.

If you are getting occasional “candle flames” coming from the cut while you are cutting but they do not stay burning as the laser moves on, then this is not unknown behavior, and in some circumstances cannot be avoided. However, If you are not using magnets, and all the lenses are cleaned (including the one under the left shelf), and the head fan is doing its job, you might try a higher speed, or different materials.


I’m terribly sorry to hear that you’ve been having trouble with your prints.

From the Glowforge Manual page 5:

A small, candle-like flame where the laser beam strikes the material is normal. This flame should move with the laser and should not remain lit when the laser has moved past.

If you are seeing this behavior more often, typically this is a sign that the air assist fan needs to be cleaned. You can find those instructions here, if needed: Cleaning Your Air Assist Fan.

If the trouble continues after cleaning, then the air assist fan may need to be replaced.

Could you please let me know if you are still having trouble while using Proofgrade materials? If possible, post a short video of the test print below and I can advise if additional troubleshooting is needed.

Cut Through Test Instructions

There are several things that need to be checked if the laser doesn’t cleanly cut through the material. We’ve discovered that photos don’t always come through well in emails, so I’ve included several links that will take you to reference instructions and photos. Please turn off your Glowforge and check the following:

Once all these things have been checked, please perform the following test print.

  • Print the Gift of Good Measure on Proofgrade material, using Proofgrade settings.

  • When the print finishes, leave the lid closed and wait until the fans stop and the picture updates.

Check the completed print:

  • If the Gift of Good Measure fails to cut through, take a photo of the front and back of the print and post these photos in your reply.
  • If the Gift of Good Measure cuts successfully, please try another print of the design you experienced the issue with, and let us know the results.

It’s been some time since we’ve heard from you. If you’re still experiencing trouble, could you work through my colleague Chelsea’s steps above?

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It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email