Cutting .020 PETG and getting jagged edges like acrylic?

[Lasergui (Johnny J)]

Hey everyone!

Using lightburn on my 100w and loving it a year in! I am cutting some PETG for a customer and the edges are continuously coming out jagged like I was cutting acrylic. The customer is requesting badges for their company, those badges have double sided (laser safe) tape on the other end.

My settings are 18 mm/s, min power 18, max power 31. I am noticing the edges are coming out with a tiny jagged cut on them. Nothing crazy but the edges are jagged. Also, I’m noticing the corners of the items are burning as if the laser has sat there for to long? Are my min settings not correct? Is it an x or y issue?

[bernd.dk (Bernd)]

@Lasergui

coming out jagged like I was cutting acrylic

What do you mean by that? I have no uneven edges or similar in acrylic (up to 6 mm), PE (2 mm) I also do a little, it is also fine in the edges but tends to turn black from soot which can be removed.

[Lasergui (Johnny J)]

I will show a photo once I go back into the shop. The edges are kind of like a coin effect

[ednisley]

@Lasergui

18 mm/s, min power 18, max power 31

That seems painfully slow. I’ve been cutting 0.6 mm = 23 mil PETG at 75 mm/s and 60% with a 60 W laser and getting pretty good results:

I was concentrating on the engraved / painted hairline, but the cut edges came out well, too.

With a 100 W laser, you should be able to crank up the speed a lot and get much cleaner results.

A few more pix on my blog:

Homage Tektronix Circuit Computer: Laser-Engraved Painted Hairline

[Lasergui (Johnny J)]

Hmmm ok. Maybe it’s because they are requesting it also be cut with the tape on? It has to be either made more powerful or slower to accommodate with the tape.

[ednisley]

@Lasergui

cut with the tape on

A 100 W laser should cut tape like paper unless it’s absurdly thick.

I’ve been cutting 1.5 mm = 60 mil acrylic with 3M low-surface-energy tape with no change to the usual settings: 20 mm/s at 50% with a 60 W laser.

Some 3 mm acrylic cut at 10 mm/s 70%:

The backstory of that piece on my blog:

https://softsolder.com/2022/09/13/high-impact-art-coaster-5/

As a rule of thumb, faster speeds at higher powers produce better results, because the surrounding material spends less time sweltering in the heat.

Perhaps re-running a cut test matrix is in order.