Printing beyond PLA on an Ender 3 can be tricky. Here are a few tips to get you started with printing PETG, a filament that is stronger and has some qualities like better heat resistance than PLA. If you head into a print with PETG using your stock tried and true PLA settings, you may be up for a surprise – it just isn’t that easy. After some testing, here are some tips that will help you get started:
- SLOW it DOWN – Running PETG through your Ender 3 is going to be troublesome on many prints running it through at the stock 60mm/s. You need to slow it down. 40mm/s may work, but 30mm/s is probably the sweet spot for this machine and filament. This one is going to be the key to your success. You might get lucky on some prints, like cubes or anything that is pretty continuous in laying down a layer, but for anything with even a bit of complexity, just slow it down.
- GET the TEMP RIGHT – This one is going to vary. You can choose a nice test cube and start at the low end of the temp range for the PETG you buy, let it print for a while, and up the temp by 5-10 degrees. Keep track of what you are doing, and when you are done give the layers some pressure with your thumb and find out where the strength and layers are really holding tight. If you head too high, you will get a solid print, but you will end up with stringy prints that take a lot of cleanup or just plain fail. Also, you will note that when you start getting to that sweet spot, the color will start to change from a milky white to clear. This is when you are getting the temp right. I find that most PETG likes it HOT! Try 250C – this may just be your Ender 3 sweet spot too.
- FAN all DAY LONG – Sure, let the first layer or two go down without a fan to get a nice adhesion, then blow on! Let the fan run on high, add better cooling by printing a better cooling duct for your machine (I like the PetsFang on Thingiverse – even went with the dual blower version).
- BED HEAT – PETG does not require a heated bed, and you may not need any heat there if you have a nice sticky magnetic mat or tape or the like but on glass and some other surfaces you may find that getting the surface up to 70C will help a bunch with keeping the print down, without warping or just plain coming loose.
- CLEAN the NOZZLE – Going from PLA to PETG or any other high temp filament is a huge bump up over what you have been using for PLA. Heat up your hot end to 250 degrees and let it sit for 15 minutes and clean it very thoroughly – pulling off everything you can find, even wire brushing around before you get started. You will not be happy if you skip this step and find an overnight print that has lumps of that awesome orange PLA that has dripped into your new PETG piece of trash.
- FLOW – Increase the flow (OK maybe decrease – but usually increase). PETG needs it hot, and if your hot end doesn’t keep up (slowing it down as I said in #1 helps a BUNCH) it will lay down layers that don’t have enough material. Use your slicer to increase the flow to 105% or more and see if the layers go down happier. This one you will need to test yourself. If you are doing a bunch of PETG prints, you may even want to calibrate the machine to the filament and your extruder to get it just right.
- THINK SUPPORT – Here you may want to just rethink some of the support that you are planning on printing for your model. I have found that the support blocking in Cura is useful for PETG sometimes – eliminating support that is unnecessary and causing you stringing issues that bleed into the quality of the finished product. Mess around here and find out which supports are going to work, and which are failing you. Another great thing to look into (in addition to standard brims potentially) is the ability to support your support with support brims – lol. Check it out in Cura 4.x, you can add brims to your supports while keeping skirts as your starting layer.
- BABYSIT those first few layers – and give them a a helping hand if need be. The first few layers are key to a great print. Babysit them for a while and use tweezers and clippers to remove anything that you can easily remove without stopping the print. Often a bunch of stringing or pulled over support issues can be solved by removing the offending clumps early on, making new layers take over and saving your print. This goes for any type of filament, but taking the time with your PETG will pay off even more in my experience.
- Lastly, use a profile for your slicing software that has some great extrusion and speed settings for retraction. This one should get you going for PETG if you are using Cura: