PETG combines ABS's strength with PLA's ease of printing. Learn the best PETG print settings, including print speed and retraction settings!
A Rising Material Trend
PETG is short for polyethylene terephthalate glycol-modified. That could mean something to you if you’re into chemistry, but for the rest of us, it’s simply the most-used type of plastic on the planet (in the form of PET). You can find it in plastic bottles, food containers, packaging, toys, kitchen utensils, and more common plastic products. In addition, this recyclable plastic can be injection molded, blow-molded, thermoformed, bent, cut, and in recent years, 3D printed.
We won’t go into the details of PETG chemistry in this article but will instead concentrate on 3D printing with it as a filament. Before we dive into printing tips, here are a few of the material’s characteristics:
- Glass transition temperature: 80 °C
- Density: 1.27 g/cm3 (which is higher than PLA and ABS)
- Resistant against most chemicals (such as acids, alkali, and solvents)
If you’re still not convinced and don’t want to buy a spool just to find out what all the fuss is about, you can always have something made in PETG through an online 3D printing service. The question is, which to choose? For a comparison of printing services around the world, check out Craftcloud, our 3D printing service marketplace.
Warning: Experimentation Advised
PETG is a very useful material that has good mechanical and visual properties. But it could be hard to print, especially if you’re a beginner. You can find a lot of advice on the internet about different settings that could contradict each other. The truth is, settings for one printer do not necessarily carry over to others. Very often, you will have to adjust some printing parameters after changing the spool of PETG you’re using.
With PETG, one thing is certain: You’ll have to experiment to find the best parameters for your printer. This article should give you a good starting point.
Setting Up the Bed
Let’s start from the bottom: Make sure your bed is leveled and clean.
Compared to other filaments, where you might have a problem with bed adhesion, you might have the complete opposite problem with PETG! By its nature, PETG will stick hard to a bed, so hard that a piece of your bed could come off with your print. Therefore, you’ll probably want a protective layer on your bed, such as glue stick or blue tape.
If you’ve printed with PLA or ABS before, you’ll know that the gap between the nozzle and bed has to be tight. PETG is different: it needs a decent gap. If you use a piece of paper for adjusting the gap between bed and nozzle for PLA, use three sheets of paper for PETG.
While you can print PETG without a heated bed, we recommend one. Most manufacturers will suggest temperatures between 70 and 80 °C, but you can go as high as 100 °C. Start with 70 °C and gradually increase it if you notice any bed adhesion problems.
Temperature & Retraction
Temperature and retraction settings for printing PETG are closely related.
Temperature
PETG will typically print at temperatures between 220 and 265 °C. But before you heat up your nozzle, remember that hot ends incorporating PTFE tubes are capped at 250 °C – anything hotter than that will damage the hot end.
Nozzle temperature plays a major role in print quality. Too high a temperature and you end up with lots of stringing and oozing, but too low a temperature and your extruder will start skipping.
Here’s an easy test to see if you’ve got the hot end temperature correct: Start with the temperature as low as 220 °C and do some test prints. If you hear a knocking noise during printing, your extruder is skipping, and you should increase the nozzle temperature by 5 °C. Repeat the test until the extruder doesn’t skip.
As mentioned, when printing with high temperatures, there’s a risk of stringing and oozing. And since PETG is a very strong and elastic material, strings are hard to remove. If you are at the lowest temperature without extruder-skipping and you still have stringing, try adjusting your retraction settings.
Retraction
Don’t go with high speeds here; it may work with ABS and PLA, but it won’t work with PETG. Set the retraction speed to around 25 mm/s for both Bowden and direct drive extruders. Retraction distance should be set at about 6 or 7 millimeters for Bowden extruders, and 3 or 4 millimeters for direct drive extruders. With PETG, retraction speed is more important than distance. If you still have oozing and stringing, try lowering the retraction speed.
One more parameter that will help in reducing oozing is the travel speed. PETG tends to drip from the tip of the nozzle, especially if the nozzle temperature is high. To combat this, try increasing the travel speed as high as possible.
Fans & Cooling
PETG will print quite nicely without fans. Unlike other materials which require fans during printing, PETG actually does better without them. If you notice cracks and delamination in your prints, turn off the fans because printing without fans increases layer adhesion.
You should use fans only if you want more details in your print, or if you’re printing bridges.
Supports
Since PETG has very good layer adhesion, it could be very hard to remove supports. If you’re lucky enough to have a dual extruder 3D printer, your best option is to use soluble filaments, such as PVA or HIPS.
But if you have a single extruder printer, not all is lost. Leave a gap between the support and your part. A 0.1-mm gap is a good place to start, and it usually gives good results. As with all other parameters, you should play around with values to find the best fit.
Speed
PETG is very sensitive to print speed. Print too fast and you’ll have poor layer adhesion, extruder skipping, and low print quality, but print too slow and you’ll end up with deformed parts, stringing, and oozing.
You’ll have to find the sweet spot with the printer and filament you’re using. A good place to start is around 50 mm/s. We suggest 25 mm/s for the first layer and the outer wall, while travel moves should be as fast as possible, at least 120 mm/s, to avoid oozing.
