Can the lasers "weakens" during a project?

I’m having a challenge with my current project (multiple acrylic 3 inch key chains).

I am currently cutting 4-5 at a time because I am new and don’t want to risk a mistake cutting the whole sheet. ( so my projects are under 2 hours and 2 min or less of cutting)

By then time I get to the 4th or 5th key chain the laser stops cutting all the way through. It’s very close but seems like it becomes progressively harder to get them off until by # 4 they are stuck on the sheet.

Anyone have any tips?

I have tried:
Cleaning the lenses and the mirror
wiping out below the crump tray/checking crumb tray placement.

Appreciate any thoughts. :slight_smile:


Are the items that are not cutting through consistently on one side or another of the crumb tray?


It is technically possible, for a variety of reasons… loose connections on wiring to the tube, the power supply is failing and providing lower strike voltage as it warms up, the tube overheating due to inadequate cooling after the coolant has warmed up… But it’s rare for any of these in a Glowforge. They have good quality control, good quality parts, and good firmware.

I do vaguely recall feeling a similar way about my tube “weakening” after some use in my last Glowforge. I don’t know if I ruled that out, or it just became irrelevant, because after not long I wasn’t able to get full power output even from a cold start. The tube was at its end of life. Tech support slowed down all the Proofgrade settings on my machine to buy me some more time, but eventually I had to replace it to get back to full power.

It was a heavily used machine for several years and these tubes do have a lifespan measured largely by their hours of use.


Have you made sure that the material is absolutely flat on the bed? Zero cupping or bowing in any direction? If your optics are completely clean (how about the mirror inside the head?), this is the most likely culprit.

Good luck!


There is probably more than one possible reason for diminishing power, but I have experienced this one.

Once the exhaust fan grill had face-loaded with enough debris to prevent sufficient airflow, the laser stopped to cool and restarted several minutes later. The line under the nose of the white walker is where it stopped and restarted. As the temperature increased the laser became weaker, and when it restarted the power had returned.
At least that’s my interpretation.


Could it have simply been less smoke present between laser and workpiece after the pause?

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That occurred to me as well! I questioned that in a conversation here with a company engineer and she assured me the absorption from the smoke was negligible.


Think JWST. Infared can “see” through smoke when visible light cannot. Make it a film of even the slightest on a window and the power reaching the work drops, though much of that I think is blurrng. What I find confusing is that the beam has a lot of trouble making it through a flame. Without proper air movement, a small candle like flame develops and the power actually cutting is very reduced.

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I wonder if that might be due to refraction from the heated air and cool air boundary?

I have to admit that I haven’t seen this problem, but I also don’t usually get flareups.

EDIT googled it and looks like I may have been on the right track:

The interface between the hot air in the flame and the colder surrounding air tends to bend light away from its forward-propagating direction. This deflection of light at the interface of different materials is called refraction.


Have the fan go over a decent neomagnet and you will see it. Also, a bed pin or other obstruction interrupting the airflow.

Sorry for the delayed response I was trying (yes this whole time) to make a small shape to test this theory.)

It is 100% the time the laser is cutting. Even doing 4 small rectangles about the size of a match by the time the laser got to the 3rd one the paper on the back wasn’t cut and the 4th one it had to be forced out leaving some rough edges on the acrylic.

Looking through these other responses now to see if I can understand them! :slight_smile:

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Thank you for the response. The acrylic looks completely flat to me. I ran a test that started in the opposite direction of my last cut and it cut clean on this attempt in the same area it did not cut through the last time.

I did watch a video and did all of the lenses and the mirror.

Someone below posted about the fan being full of debris and the laser heating up and I’m wondering about that now.

Appreciate the support!

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Had the same type of thing happen to me a long while back when i made my church’s On Air sign. Was a multistep pass-thru process. A portion was done a few hours after the rest as I had to sleep and the engraving is clearly of different quality than the rest of the sign.

The curved and leg portion of the “R” is of a definite different quality engrave as the rest of the letters.


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