Larger than normal flame when cutting

I’ve been cutting a LOT recently. But I noticed this past weekend, that the flame when cutting seems bigger than normal. The smoke seems to be gunking up the lens faster. At this point, I’m cleaning the lens after every 2nd cut, or else the cuts don’t work well (like they are out of focus).

Here is a video of the flame. It was bigger than that a few seconds before, but by the time I got my phone out to record, it died down a bit.

This is with the same material I’ve been cutting for the past year. I also noticed a bigger flame when cutting baltic birch as well.

I tried the following:

  1. Cleaned out the back exhaust fan.
  2. Cleaned out the lens, mirrors, and 2 other glass surfaces.
  3. Removed the head assembly, and cleaned out the air assist fan with compressed air.
  4. Completely cleaned the whole bed and the rest of the GF.

Is there anything else that I’m missing?


Even though you blew out the air assist fan, this certainly looks like it’s not up to snuff, which is odd since the fan speed is a monitored value. If it’s slow, it should trigger a fault.


You’re talking about the air assist fan that is hidden underneath the laser tube? (In order to reach it, you have to either contort yourself into a pretzel or remove the carriage plate.)


Yes, I removed the carriage plate, and blew air all over the air assist fan. A bunch of gunk fell out. Perhaps I need to do a more thorough cleaning?

I imagine that would do it. Maybe you just got some “looser” material? (More air = more flame.)

If it continues there might be a problem, but i’d try it on something else too. *(I’ve noticed some flames occasionally on stuff that shouldn’t be that flamey as well. Maybe we’re just cutting too deeply. You might be able to speed it up about 5-10 points and reduce the flaming.


That looks to me like the air assist fan is not blowing correctly. The flame is straight up or sideways, not forward. When I get a flame like that in mine, it points toward the front of the machine. You can also see smoke headed to the left of the machine. The air assist should override the exhaust draft.


did you disassemble and remove the scoop? buildup there can affect the airflow even if it’s not directly impacting the fan speed. When I took mine apart for the first time there was essentially a wall of compacted dust along the lip of the scoop.


I just came in from doing another cleaning. I did not remove the “scoop”, but I did clean inside of it. And there was some build-up, but not significant. The flame still appears to be there when I’m cutting.

The flames seem way worse when the head is on the left hand side of the machine than when it is anywhere else (looking down from the top).

When the machine is running, and the laser arm is forward, you can see the AA fan from the back. Check to see if it is running. I’ve had trouble with mine and could see it was not running at all. I did get the Air Assist warning, however.

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I just checked, and it’s definitely spinning.

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BTW, all you guys are awesome for helping out!


Well, that’s a good sign. Mine couldn’t be corrected, even with a new carriage plate/fan assembly. Waiting on a replacement machine now.

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I hope the new one works for you.

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I had that happen, and I found there was a crack in the metal lens ring so that the magnet in the head was not holding it in place – the flame was from a mis-focused laser.

I have not yet had enough build up on the new machine, however, when there was a great mess in that fan I was able to put a vacuum hose on the end of the of the scoop and pour alcohol hand sanitizer down the intake.

With the vacuum cleaner running the air movement would spin the fan while the thick alcohol sanitizer dissolved all the gunk to be sucked in by the vacuum cleaner, and leaving the vacuum on for an hour would totally remove all traces of the alcohol without putting any power to the Glowforge.

If that fan is spinning well it should be pushing enough air out the scoop to get the flammable gasses away fast enough to not catch fire. If the smoke does catch fire a lot then it will damage the work and reduce the depth of the cut and potentially damaging the lenses and head.

Note that strong magnetic fields will interfere with the fan causing it to stop near such fields.

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Definitely a “Beyond the Manual” solution.


Looks like your air assist fan is in need of replacing.

I’ll follow up with you in email to arrange the details.

I’m going to close this thread - if the problem reoccurs with the new plate, go ahead and post a new topic.