Settings for .060" PETG -- Updated


#1

PETG is a neat material, being food-safe, appealingly clear, and impact-resistant. It also has a reputation for being somewhat difficult to cut, as it melts and sticks to itself, not vaporizing as cleanly as acrylic. People also complain about white edges and raised edges. Still, many say you can laser cut it cleanly, and I have bought PETG laser-cut pieces that looked fine. So, let’s figure this out.

UPDATED settings for .060" PETG sheet
(actual thickness per calipers .070")
Vendor: https://smile.amazon.com/gp/product/B00ERVS88E
Speed: 250
Power: 100
Passes: x2

Compared to the previous setting of Speed 400, Power Full (Pro), Passes x2 this produces a slightly less polished edge, but a much better surface quality. Overall quality is adequate, but this stuff just isn’t as beautiful as acrylic.

Small or closely spaced cuts suffer badly. These melted cuts are 2.5 mm diameter circles. I cannot find any settings that would cut this test object successfully, including low power and 4x passes.

I’m probably giving up on cutting anything like the above, but PETG should still be useful for a more limited set of designs.


Shaker top for small mouth Mason jar
Pinball upper playfield
#3

Also, here is a nice materials application guide for PETG. It discusses thermoforming, chemical resistance, all kinds of good stuff.

https://www.curbellplastics.com/Research-Solutions/Technical-Resources/Technical-Resources/VIVAK-PETG-Fabrication-Guide


#4

I just got done cutting PETG (shim stock .020" thick from McMaster https://www.mcmaster.com/#9513k23/=1c6s9so).

I tried my best guess at it (S: 300, P: Full (pro), Pass: 1x).

Smells terrible. 11s job, shouldn’t smell too bad, right?! my basement shop with no windows and not cutting a hole in my rim joist to vent…and filter now pushed back even further…should’ve delayed shipment…anyways…

Power was to much and speed was to slow. Edges severly melted, and backside was blackened in such a way that looks permanent (has pattern of crumb tray so I think it’s char that melted back into the molten plastic).

So then I decided to look on here if anyone had cut this…probably should’ve done that the other way around! :slight_smile:

This is the back side.

Close up of the back side to show molten and charred edges.

!

Next time I’ll carry this back upstairs to my garage and either use masking or a backer piece of some sort. I’ll also think of going 500 speed with 100 power. I’ll try and comeback and update!


#5

Yep, definitely too much. I find flashback usually has the crumb tray pattern – the honeycomb acts as a sort of collimator, and also confines the smoke.

Thanks for being our guinea pig :wink:


#6

My $.02 contribution: .025" white PETG shim stock from McMaster Carr … cut at 200/50/1 pass (GF Pro) gets the features done, but takes a final manual tug/tear to set the part free from the sheet. It also ends up with yellow edges and streaks of black smoke on the top side, downwind of any concentrated features. So not perfect, but it gets the prototype done.
I, too, have had clear .020" PETG cut by Big Blue Saw, and it was totally clean. A nice thing about PETG in thin sheets is it can be bent on a sheet metal brake, so it works well for prototyping or for applications that want bent forms.