Excessive smoke/constant cool down mode/preparing print won't stop running

I am at a loss and hope someone can help.

Two things: For several days, the preparing your print runs constantly and will not go to the next step. There are. times that the purple light goes on and lets me cut, but most times I have to log out. This happens literally all day. Is there an issues going on with the software? It’s extremely frustrating.

Cool down mode is happening constantly. I have tons of smoke in my machine. I have an in line fan. I have taken it apart, cleaned all of the blades, I have cleaned the air assist fan. The in line fan tube has smoke coming out of it, so I know it’s doing it’s job. What else could be causing this? I am really worried something is wrong with my actual machine. I am using 1/8 MDF and have been using for awhile, with no issues.

The first problem may be an issue with the Glowforge not being able to stay connected to your wifi. They’re pretty picky about their signals…there’s a section on the support website with some tips for checking wifi issues (other appliances interfering, etc.)

MDF burns SUPER dirty, and tends to clog things up quickly. If there’s smoke in your machine, there’s something obstructing the path of ventilation, even if some of it is managing to escape. You didn’t mention your exhaust fan; it may well need cleaning. Also check the air intake under the front right corner to make sure it hasn’t gotten blocked by something.

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I had a smoke issue after a few months, it turned out to be the exhaust fan grill on the back of the machine. The grill had become blocked by ash and bits of mask.
Pull the vent hose off the back of the glowforge and check to see the grill is clear.


It looks to me like your air assist fan is not working properly. When smoke starts pooling like that around the head instead of being blown strongly to the front, the fan might not be working correctly, or it’s possible that it was installed backwards after the last cleaning if you took it out to clean.

So that would be the first thing to check. If the fan isn’t blowing out the flame, it’s going to cause overheating issues too.

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Thank you Jules. So dumb question but I don’t have my air assist fan running because I have an in line fan. Did you mean my in line fan? Sorry, my husband usually does all of my GF trouble shooting and of course is out of town so I am. trying to do it on my own…

Thank you printtolaser, I am going to try this now. Hopefully this is the issue!

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The air assist fan is the one behind the head on the laser arm. It’s not impacted by the exhaust fan switch. The exhaust fan at the back of the machine is the one that is shut down by the switch when you are using an inline fan.

Your air assist fan might need to be cleaned if that wasn’t done, or if it was done, it might have been re-installed backwards. (Very easy to do.)

The instructions on cleaning the air assist fan are here:


There is a small fan behind the head that blows the smoke forward that could be getting gummed up. If it is not working there are many possible problems it could create, including the “overheating” light. Also now that we are moving into warmer weather actual overheating can be more likely.

I would also look to your inline fan and its rated CFM. I have a Vivo 190 CFM that is adequate only when there is little smoke, but most woods and certainly MDF (that I never use for many reasons) I have to run both the main exhaust fan and the inline fan. Folk that have like 400 CFM fans can depend on those alone usually.

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Printtolaser- OH MY GOD…It was 100% blocked with junk. Thank you so very much! What a mess…


Great! When I found that issue on mine I was very relieved!
All that stuff blocked the machine from venting properly.

I just poked at the debris with a piece of wire to loosen it and sucked it out with a vacuum. It’s the particulate in the smoke that accumulates, essentially ash.

With that much accumulation on the grill, it’s a good bet your air assist fan on the head carriage could use cleaning as Jules said. Follow the directions in the link she gave.

What is the most important to keep clean are the optics. Two windows in the beam path, the mirror in the top of the head and the actual focusing lens in the head.

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Hi @mollyandshea. I’m apologize for the delayed response, but it sounds like you got some great advice from fellow owners to resolve the exhaust vent trouble. I’ll go ahead and close this, but feel free to start a new thread, or write us at support@glowforge.com, if you run into any further trouble. We’ll be here and happy to help. Thank you!

Hi @mollyandshea. I apologize for my oversight noticed that you’re also working with us through an email support request. To avoid any miscommunication, I’ll go ahead and close this thread still so we can consolidate any further troubleshooting through there. Thank you.