Melty - ish inside edges when using Acrylic - Settings help?



Hi. I cut my first acrylic using GF last night. I used black proofgrade. When the cut was done and I removed the item, the outside lines were clean but right inside there is a wavy melty-ish line that I can see. I have not had this happen with other laser cutters that I’ve used. I allowed the app to select the setting based on the material but am I just going to need to play with the settings to avoid this, is there some kind of settings chart that I’m not aware of, or does this just happen with gf?

Melty - ish inside edges when using Acrylic - Part 2 - Issue closed but not resolved - why?
Thick acrylic

Maybe this is related to reports of “slumping” we’ve gotten from Jules


Might not be the same thing which is why I didn’t mention it. It doesn’t sound like it. I don’t notice melty lines, but I use my own settings. :slightly_smiling_face:

Posting a picture of the meltyish line would help people to let you know if it’s something they see regularly. I don’t cut a lot of acrylic, but @mpipes does.

If you can show a picture of one that doesn’t have it from the other lasers and tell us what kind of lasers were used, that would also help folks to figure out what’s causing it. :slightly_smiling_face:


Along the same lines, I’d be interested in a photo of your slumping. I plan to use a lot of acrylic.


Oooh! Sorry, I didn’t take any pictures of it, and it’s not really visible anyway. It is measurable if the tolerances are too tight. Plastic melts when it gets hot and tends to follow gravity.

You really don’t need to worry about it unless you are trying to press fit acrylic together, and I think you’d have to be insane to try that. (Rather like me.)

For normal design…it’s not going to be an issue. The kerf gives you plenty of leeway. :smile:


I don’t think it’s slump, I think it ablates more towards the surface. 2 pass cutting of acrylic fixes this issue and leaves much cleaner, straighter edges. Single pass cuts will always slope outwards towards the bottom unless you use so much power you get flashback


Yeah it does that too with a surface focal point, and it’s much more visible in acrylic. :confused:

I’m going to try a second pass to get the slope (which might be a better word than slump) out of the way if I decide to mess with it again. I hadn’t thought to cut that out of the way, (good idea), but I have experimented with moving it through the focal point. Those results were so-so on the thin acrylic I was cutting.

It is melting some though as well…I’m getting differences between the surface and the base of the cut.


Here is the picture of the gf cut (black) and not gf cut (green). You can see here both edges inside have a visible line but it’s smooth.


Then you can see here on the other side of both, the green, non gf cut is still smooth and the black gf cut its wavy. I’m not sure what side it was from as I wasn’t expecting any difference when I removed it and removed the sticker part.

I’m a beginner at this point, so I’m looking for “adjust this particular setting” type of information. The technical information is interesting but does not do a lot to help me at this point. I do want to learn but currently I would like to fix this problem.


Wow, I’ve never seen anything like that cutting acrylic on an Epilog machine.


Looks like you’re using too much heat. Acrylic cuts very smooth normally. Is that 1/8"?
Now there is often a difference of cut quality and settings between cast and extruded. I’ve had issues with some colors, mainly black, with extruded acrylic…but nothing like that…
I cut on a Universal laser though. But have seen loads of acrylic cut on the :glowforge: that cuts perfectly fine.
Were your setting for cast or extruded acrylic? Because they are not the same as for cast…


I was using gf proofgrade, so whatever the machine auto sets it to is what I was using. It supposedly sets it “automagically”. Clearly not.


Oh…hmmm thats NOT supposed to happen then :anguished:


No, that isn’t normal. The pics will help support to figure out what happened.


Try a test on the gf without the paper on it. See if that’s giving you that problem. Also try manually selecting “1/8 colored acrylic” from the menu and using those settings. I’ve had no problems with those on my cuts.


Contact support.

I’ve not seen that happen with Proofgrade black whether using automatic PG settings or my own settings. If you’re using PG black and PG settings, it definitely should not be doing that. It should be super crisp and clean.


Even the green doesn’t look like a normal laser cut acrylic edge to me. The surfaces should be flat right up to the edge. How big are these pieces?


By posting here, support has already been contacted. New threads create the same kind of ticket in the system as sending an e-mail.


Thanks, I wasnt paying attention to the section of the forum. Actually, I have this section on mute but I was tagged so I followed the notification I otherwise would not have received.


As suggested, I tried removing the paper and selecting 1/8 in acrylic. It turned out even worse. It was picking up the pattern from the crumb tray. I was able to determine that the problem is coming from the underside.