Settings for .060" PETG -- Updated

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.

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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

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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!

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:

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.

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I used the updated settings and it worked perfectly the first time. We are donating face shields to the Coronavirus cause to get enough for Medical and Dental professionals.

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I wonder if you could get better results if you put the PETG in the freezer before? Kinda silly but it could possibly reduce heat buildup a bit and help with some defects? I doubt it but could be neat to try.

I am cutting 0.030 inch sheet PETG, to make the Prusa Face Masks https://www.prusaprinters.org/prints/25857 and speed 250 power 100 1 pass is working perfectly.

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That is good to hear. Would you be willing to do a small test on scrap?

One of the things I want to do with this material is make shaker tops for Mason jars-- that means lots of little holes. When I tested this on 0.060" material it was a melted mess.

If you could cut a small part of the of that pattern, it would be very illuminating. This piece is about 1.3" x 1.3".

image
If you are game, here’s a vector file.

jar_shaker_top_test holes.pdf (285.8 KB)

Any chance you have a svg template for prusa masks that you could share?

https://www.prusaprinters.org/prints/25857-prusa-protective-face-shield-rc1

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I got good results cutting PETG sheets with 1.0 mm with this settings:
Speed: 300;
Power: 90;
Pass: 2;
Focus: 0.5 mm

The file they provide is a DXF, which took some effort to convert correctly to SVG (Illustrator and online converter failed, had to use Fusion360) Mask This cuts on the GF fine.

I didn’t try your file, but the Prusa face shield has quite a few holes less than a quarter inch across and they all cut just fine with the settings I posted, so I wouldn’t expect your slightly smaller holes to have trouble.

hi, i’m also trying to make face shields to donate - i tried the .06 and it seems a bit too thick - is that what you are using?

I’ve used 0.030. The Prusa design can work up to 0.040, or as thin as 0.020.

Thank you! Any idea where I can find it - everywhere I’ve looked online is sold out.

Would it be possible for you to provide the SVG file you were able to convert? I have been asked to participate in manufacturing these masks for my local hospital. I have teamed up with a company that is doing the 3D printing, but I can’t seem to get the file to convert properly. Thanks in advance!

It’s in their post:
image

Whoops! I totally missed that. Thanks for looking out!

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