Aug. 2, 2021
For many years the standard 3D printing filaments were PLA and ABS. 3D printer users knew that if they wanted something decorative, print it in PLA and if they wanted something structural, print it in ABS. That all changed once PETG 3D printing filament entered the scene. Not many 3D printers had all-metal hotends that could support it, but those that did were able to print structural components using a much less temperamental material. Nowadays PETG has almost entirely replaced ABS as the "structural-material of choice," with everything from end-use jigs, fixtures, and products to entire 3D printers being made using PETG. In order to 3D print with PETG 3D printing material successfully, there are some hardware requirements and tips you might find helpful, so let's jump into it!
PETG is an extremely common polymers used today that you likely encounter without even realizing it. Basically any clear plastic bottle is going to be made of PET (Polyethylene Terephthalate) or PETG (Polyethylene Terephthalate with a glycol modifier) and in fact many consumer 3D printers utilize PETG or some derivative to makeup their 3D printed structural components. When used as a 3D printing filament, PETG has found its home as the more accessible "durable 3D printing filament" due to its relatively stable 3D printing properties that make it easy to print and yet capable of being in low-heat or high-strength environments. In a sense, it combines the most useful characteristics of ABS with the ease of printing (and color availability) of PLA.
You’ll often see references to PETG in one of the following forms: PET, PETG, PETT, and many others. This can make it seem like these are many different filaments when in reality they are just slight variations in the formula to create a material that is more translucent, stronger, or more flexible. In terms of print settings, across all these variants they will be approximately the same, with some minor tweaks here and there to reduce stringing or improve layer adhesion.
If you're used to printing with PLA, then you might not have considered a unique attribute of PETG: that it's ductile. Where PLA may be able to withstand more force without breaking, when it hits the threshold where it'll break it is very sudden and without warning. In contrast, PETG will bend a little before it breaks, so you can see a failure before it happens. It's the different of printing a PETG shelf bracket that's starting to droop and a PLA shelf bracket that dumps your books onto your desk and monitors.
With PETG you can also take that ductility and use it in the design of some purposefully flexible geometry. Snap fit enclosures, where small tabs bend out of the way and snap into a channel once a lid is fully pressed in place, are a beautiful opportunity to utilize PETG. Or you can design a part that needs to rigidly hold something else without being too difficult to insert, like a bearing holder on a 3D printer part.
There are many variations to the PETG formula, which makes specifying one temperature to print at a difficult claim. Some have additives that bring their printing temperature significantly lower while others bring the temperature significantly higher. Essentially, start with 245°C and play around with 5°C higher or lower to find the ideal print quality for you.
Some 3D printers utilize a PTFE (teflon) lined hotend as it is easier to manufacture than a hotend that is all-metal from the heatsink to the nozzle. PETG's printing temperature is right at the threshold of the temperature that PTFE begins to degrade, so some 3D printers might be able to get away with lower-temperature PETG filaments that have an ideal temperature at 240°C or less. For the most part, PETG does require an all-metal hotend to be able to tune your filament to its fullest, as in while you may have successful prints at 240°C, you don't achieve full strength until 255°C.
In general, PETG is non-abrasive, but once you start playing with additives it becomes a case-by-case basis. Sparkly filament isn't abrasive despite having non-PETG material in it, but it's common to add carbon-fiber to increase the stiffness and strength of the finished 3D prints, which is extremely abrasive. An easy way to avoid these concerns is to swap over to an Olsson Ruby nozzle or a Nozzle X when you want to use these materials.
Layer cooling is only occasionally necessary. This does depend on the 3D models actually being printed, as moderately sized models can be printed without cooling and come out beautifully, but tall and thin models with short layer times may need some gentle cooling to hold its shape. 50% is the maximum you will need for extreme overhangs or short layers, otherwise you are free to leave the fan off for the best layer adhesion possible.
E3D v6 All-metal Hotend
For the best chance of success, you will want to make sure you have a heated bed set to 65°C. Some PETG is more warp-prone than others, so higher temperatures may be required to give them enough adhesion to the bed. If you're having difficulty, bump the temperature up by 5°C at a time until adhesion improves.
There are always new and exciting methods for bed adhesion being developed, so it's important to have a good grasp on what each method is best used for. You can check out our 3D Printing Essentials article about bed surfaces to fully understand the pros and cons of every bed surface you might come across while 3D printing.
In addition to build surface upgrades, there are also a wide variety of 3D printer adhesives that you can apply to your 3D printer's bed to get a great first layer. These adhesives are specifically developed for the 3D printing industry, so you can trust they have been tested to be tried and true 3D printer adhesives. Here are the best 3D printer adhesives that you can use to get the best first layer for PLA filament:
Most 3D printer bed adhesives have the same instructions for use: apply a thin layer to the build surface where your actively 3D printing. Then, wait for your part to cool before removing - waiting for your 3D printed part to cool makes it much easier to remove, and certain adhesives will sometimes even "pop" the part off the bed once cooled.
When switching between two PETG spools and colors:
The first layer is the most important part of any print - it sets the foundation that the entire print builds on. You can check out the in-depth article on how to get a perfect first layer here, or for a brief summary of what to consider below are the few things you need to do to get the first layer to stick well.
Below is a video from MatterHackers' 3D Printing Essentials series that will help guide you in the right direction for getting a stellar first layer. In this video, we'll walk you through the steps mentioned above in detail so you can succeed when 3D printing with PETG filament.
There are 3D printing materials which are hygroscopic, which means it will actively absorb moisture from the air. This is a factor that you can't change in the material, so a hygroscopic material left out for long enough will reach saturation until it can no longer absorb water. Thankfully this is a fully reversible process without any material degradation. Best practices before 3D printing with any PETG filament is to thoroughly dry it out with a PrintDry PRO for several hours (or overnight if you have the time) and print with it immediately. Unless you live somewhere extremely humid without any temperature controls, your spool of PETG should be dry enough for use for several weeks before needing to be dried back out again.
Wet 3D printing filament doesn't just impact the appearance of your 3D print, but breaks down the molecular chains and creates a significantly weaker 3D print, which is why it's so important to make sure your filament is dry. Check out our in-depth article on how moisture affects your filament, and how you can successfully dry your 3D filament here.
There are a few key things to check when your prints aren't working. But before we look at solutions we need to have a brief description of your symptoms.
"I can't tell if my printing temperature is right "What to Look for if you are having trouble getting your PETG filament temperature right:
"I can't get the first layer to stick."
"The part has bad internal layers and top surfaces."
"The outside edges of my parts have lots of little bumps on them."
"Tall sections of my prints look melted or squished together."
"My printer will not put out any material."
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