Burning of acrylic edges

Since my latest replacement (#9 this year) I have been trying my best to just make my projects work with this machine that was delivered. This machine has been randomly burning the edges of acrylic. This project ran for 45 min, resulting in processing something I need to throw away because I can not give this quality to anyone purchasing my items.

Another issue is when I line everything up in the Glowforge dashboard, using the space available on the wood or acrylic. I press READY and start the job. The job ends and I see it made a big jump and everything cut out was moved from what was shown to me on screen and a lot of times the items are wasted because it ran into a past cut out or off the edge of the board. I understand there might be 1/8 inch move, but these moves are much larger than that and very unpredictable of when it will happen.

Another thing that I have noticed is that I have two Glowforge PRO models. When I figure out my settings to make custom depth engravings to place wood or acrylic into them, it isn’t the same for both machines. When I do these same exact settings on the other machine that has issues, it will burn much deeper and completely through the wood or acrylic, frying it. This results in me having to figure out completely different engraving settings depending on which PRO model I use. Both models have the same bulb and power, so I don’t think there should be a difference in having different settings when they are the same Glowforge models?

The details of the cuts and engravings are also different. The oldest Glowforge ( less than a year) cuts and engraves really well. The newest glowforge replacement has jagged lines, uneven engravings and burns the edges.

Can this be fixed, please?

This photo was taken of a project I did around 10:30 am on my Glowforge called #9.

It would probably be good to prepare a single test piece using the same design, settings and material, and take a pic side-by-side after printing.

Support could check the logs to ensure both machines are receiving the same data, and comment on the differences.

The only other variable should be the alignment and cleanliness of the optics.

I would assume that most of the black is caused by over burn around the outside and inside of the shape as it does not appear as noticeable around the right side. it looks like you are engraving ~50% of the material away and if you have not lowered power or increased your speed to account for that in the sections where it is lower it will over burn the backside of the acrylic and most likely make the edges bubble and discolor.

Is that actually acrylic? It looks more like poly of some sort to me. (Never seen acrylic do that when it engraves.)

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yeah, i’m with Jules on this. can you point us out to exactly what this material is? i don’t think i’ve seen that kind of messy engrave with regular cast or extruded. or do you have some sort of speckled finish on the engrave itself?

normally if i see that much charring on the sides, i would presume it’s too high powered. but the engrave looks pretty bad, too.

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This is Glowforge White Acrylic. I cut simple letters out with no engraving and I get the same awful black burns around the edges. When I use my other machine is cuts cleanly and bright white like it should.

It might help you to shoot a short video with your phone and upload it to YouTube so the support crew can see what’s going on with it. Kind of tough to tell what’s causing it just by looking at the results after the fact.

When you are cutting, are you getting a good strong air flow blowing towards the front of the machine from the air assist fan? That might need to be checked and cleaned if it doesn’t blow out the flame.

You say you’re just cutting and yet:
If it were a simple cut there would not clearly be 2 different levels to the single letter. You should post your art, and if possible a video (upload it to youtube and then post the link here).


I am saying I also cut out simple letters at other times besides these in the image (which I stated that the ones shown were engraved) and I get the same results. Black edges on BOTH engraved and cut outs of simple letters with no engravings. I can cut a simple circle and get charred black edges on the Glowforge white acrylic with this replacement machine.

We’re trying to help so that when a staff member gets here they have all the info they need to fix your issue. The info you provided was unclear, and your clarifying statement made it more so :frowning:

As to the jumping, that happens because you do Set Focus to place your work, and then it will do an auto focus to make sure nothing weird happened so the screen updates, but it doesn’t change the actual placement, just the camera image. If the cut is happening in a different place than you did Set Focus that’s a different issue than if you placed your art without doing a Set Focus - it’s likely hitting a hole in your material and thinking your item is 1/8"-1/4" shallower than it actually is.


One thing I would do is carefully inspect the plate the head sits on. There was a bad batch of wheels and they might have arrived on your latest machine, and that could cause some of what you are seeing.

One other thing, Purell and other brand name hand sanitizers do not contain the type of alcohols that cause crazing in Acrylic but could possibly remove the marking on the sides.

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I’m so sorry your print results are not coming out like you expect.

I took a look at the design file, and I noticed a couple things that may be contributing to these results.

  1. The step-order performs the engrave first, removing about half the material, before the cut occurs (black engrave portion)

  2. The cut line is duplicated in the design file (red lines)


I would be curious if you see the same charring if you did a simple test cut with a single cut line. It sounds like you did. Can you post photos and tell me about when that print was? I’d be happy to check the logs for that print.

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Thank you for your suggestions, I appreciate the help.

I cut the same exact design with out the engraving. The straight edge cuts still turn black. I did this test around 5:22pm.

Thank you for your help.


Since there are burn marks on the sides of your acrylic, maybe the air assist fan is not running properly . Is the smoke being blown away when you are cutting and engraving ?
I realize you were not engraving this time, but before.


You are working with support and I’m sure they will come up with an answer. Just curious. Seems like a lot of charring for just the acrylic masking. The acrylic itself doesn’t have any char for me. Wondering whether the acrylic is sitting on something else flammable like cardboard?


Even without the engraving, your file might be duplicating the Cut, since you have multiple cut lines close together in the file. (The red lines that @pip showed in your file.)

Watch one of the letters while it is being cut out…does the laser travel around just once when it cuts, or does it travel around again? That second pass might be charring it.


That definitely looks like smoke from something other than the acrylic, and something easily cleaned with the Purell.

Thank you for working through the instructions my colleague @pip provided. I’m sorry to hear that you’re still continuing to run into this behavior.

As @Jules outlined, your file may still be duplicating the cut, which can cause multiple “cuts” in the same area, which may lead to the charring you are seeing. Were you able to remove the two cut lines @pip outlined in their previous instructions?

If you have, and you are still running into the same snag, please let us know.

I eliminated the engravings and there is only simple cut lines. This is Glowforge Medium White Acrylic, cut on Glowforge automatic settings for Medium White Acrylic. I did watch the cut and the machine is cutting around the object in one direction and then repeating the same cut in the opposite direction.
I tested this on both of my machines and BOTH cut the paths twice but with totally different results.

These charred cuts in the photos that are attached were done around 7:15 am on my machine calle “#9”. The clean cuts were done on my machine called “Glowforge PRO”

I want to repeat that I have TWO machines. Both are Glowforge PRO models with the same power of bulbs. One cuts cleanly, engraves cleanly and has sharp lines. The other machine burns edges, engraves unevenly and leaves pixelated/rough edges in designs. This has happened since day one of receiving the machine.