Cooling Down Excessively

Cutting a 5 minute project, cutting only. It has stopped several times to cool down. In fact after cutting for less than 2 minutes is has been sitting for 10 minutes cooling. The room is 73 degrees and no obstacles are blocking the inlet vent, there are two right angle bends in exhaust hose (the length is 4 feet), and there are no obstacles at then end of hose. After cutting two minutes to take 10 minutes to cool down sounds like a long time. Is there a way to see the actual temp? Just doesn’t sound right.

Basic, plus or pro?

Was the room a constant 73 or warmer at some point in the near past?

It is a Plus, the room is and has been 73 degrees the entire time and has a ceiling fan.

Tried it again and stoped at 1:15 minutes left (I’m timing the cool down now). I don’t feel any warm air blowing out around and edges or from the exhaust hose.

One other thing to check…remove the hose from the back of the Glowforge and check the condition of the exhaust fan face plate. That can get loaded up with junk pretty easily and would block the fan, making it work harder. Might increase the internal temps if it can’t vent the hot air properly.


It’s only a month old and had good air flow out the exhaust.

the important place for temp is the front right of the machine under that corner. that’s where the air intake is. some people have reported that propping the machine up a little off the surface can get better airflow into that intake.

Maybe a silly question but have you measured the room temp in the room by the machine? Or is it a thermostat set to 73? Thermostats can have a lot of discrepancy from room to room.

73 is close to the threshold, so it might not take much to send it into cooling. A few things of note: the lid closed can create a greenhouse type environment with heat from the LEDs warming up the in-machine temp. Sunlight can also do the same.

Not saying you don’t have a potential issue, but just a couple of ideas of things you can check on your end.

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this is a good point. i have a cheap thermometer that literally sits on the table next to that left front corner so i know what temp air is going in there when it’s warmer in the summer. mine is in a finished cape cod attic which runs warmer than the rest of the house. especially with two skylights nearby. the temp variance with my thermostat is significant.

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Yeah, Inside the running GF it is about 60F right now, with the room at 52F. My hallway thermostat temp reads 68F and 15 ft away from that I’m typing in a chair at 76F (near the woodstove).


I would like to know if the code in the GF has a built in run time limit at 100% as well as a temperatue threshold upper and lower limit. It just seems like too much of a coincidence that during a 5 minute cut the stop point is within an inch or so of the same point. Also the cool down time was upward of 10 minutes. Where is the temperature measured? Is it in the cooling fluid, inlet fan, print head or in the bed area? I’m very happy with the GF but I’m interested in determine it’s limits. If 3 minutes full cut is the limit then so be it.

I extracted the logs to investigate the problem you reported. When the unit made it’s first connection on Wednesday (2/20) at about 7:10 AM (pacific). The logs indicated the temperature of the coolant was 84 F.

There are a number of things that can cause the coolant in your Glowforge to be too warm to start a print. For example, similar to a car left in the sun, the glass lid can create a green-house-effect trapping the heat from the sun. Leaving the lid open when not printing helps.

When you receive a message that your Glowforge needs to cool, if the air the Glowforge is drawing in through the intake fans (at the front right corner) is cooler than the temperature of the coolant, your Glowforge will cool down towards the temperature of the air in the room. If the room temperature is in the operating temperature range, you Glowforge should be able to cool enough to be able to begin printing again.

There are two things you can do when you see the cooling message and your room is at the correct temperature:

  1. make sure that there isn’t anything obstructing airflow,

  2. allow your Glowforge to cool

Note: if you cancel prints it will turn off the cooling fans and any heat stored within the coolant won’t be able to dissipate as quickly.

Is there a way to see the actual temp?

That’s a great idea for a feature - thanks for the suggestion! We haven’t announced anything like that yet, but I’m going to send it to our product team with a note that it came from a customer request.

I would like to know if the code in the GF has a built in run time limit at 100% as well as a temperatue threshold upper and lower limit.

Cooling pauses only happen due to temperature.

I hope this helps. Please let me know if I missed anything, or if you have any additional questions.


Very clear and concise response, thanks. I’m sure the temperature was at 74 degrees in the room and the window blinds are always closed. My next step is to install a flat thermometer to the bed surface and one to the surface located at the right of GF and near the inlet. It’s my theory that the heat is generated by 100% power and long cut. I will document and reply with results. If the results are unclear I will build an Arduino temp monitor and place at the inlet side of the GF to measure over time. Stay tuned. Has anyone ever checked the exhaust air temp during cutting? I’m sure it will be hard to measure due to humidity and air speed at probe.
Thanks again…

Stopped to cool down again.

I set two temp probes at the inlet of the GF and at the exhaust duct air flow exit.

This shows 10 minute cool down with the inlet at 76 degrees and the outlet at 81.


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I’ve placed a probe through the vent hose right at the machine outlet and, IIRC, I saw about a 5f degree positive difference between the intake temp and exhaust temp.

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I places two strip temp strips on the GF, one on the bed left side the other just above the air intake.
I observed a room temp of 74 degrees, inlet temp of 78 and bed temp of 79 while cutting at 100%.
When the bed temp go over 80 degrees the GF would pause to cool down. I believe now I can adjust the room temp to allow better temp control on the GF.

IMG_2347 IMG_2346

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I’m glad you resolved it! I’m going to close this thread. If you run into any other trouble, please start a new topic, or email us at We’re here to help!