I am using an Omtech Turbo 756 (60w). I cut circular discs out of 2mm PETG and having a few issues and looking for advice. I can get nice clean cuts on the most part, however there are still ‘horns’ on each side of the plastic discs, a slight lip which i am currently taking off with a de-burr tool.
I’ve set the focus (and tried alternative bed heights), all speed and power settings, everything from 5mm/s to 40mm/s and 10% power to 40% power in all combinations. I’m wondering if it could be worth getting a new lens? Does anyone have any experience with 2mm PETG plastic? Alternatively could this be a bed issue? I am using the stock honeycomb style bed, maybe a knife style bed is best?
Great thank you, no i have not. I will try this hopefully later today. Do you have any tips on using overcut? Sorry for the all the questions, the help is massively appreciated.
You certainly don’t have to apologize.
Overcut, you should probably test it a little with some residual material, but start with half a mm.
What is your minimum power compared to max?
I’ve misinterpreted/translated your problem, I’m sorry. I thought it was a spot where the circle closes. On some materials, e.g. acrylic you experience sharp edges on either one or both sides. As far as I know, there is no effective way to avoid it. With acrylics, which I work a lot with, I often use a gas burner, but this is risky and requires the right “feel”. I’m not sure it can be used for PETG.
Ok yes i have heard about using a heat gun with PETG, i’ll keep experimenting. I heard a different lens might help, do you have any experience with that?
No, by default I use the “original” 2" lens. The thickness and the combination of speed/power determine how good the result will be, but you have already figured that out.
The problem is that PETG has a very low melting point, so the energy deposited while cutting heats the surrounding plastic enough to raise a ridge along both sides of the kerf.
That was made in Dot Mode to reduce the power enough to not quite cut through the sheet. I colored the trenches with Sharpie, which didn’t work nearly as well as I hoped.
You may be able to reduce the ridge with more power at higher speeds to reduce the stray energy around the path, but it will require careful attention to detail.
