Is our PET or HDPE filament safe for 3D printers

Hi everyone,
I’ve started a precious plastic society at my university and am trying to convince the university to allow us to use their equipment.

BUT they think it will break their new 3D printers. Does anyone know if the recycled PET or HDPE from the extruder is safe or how to make it safe for the printer?

Thank you for your help!


Hey there!

Doing the same thing over here trying to create 3D filament. The main thing to focus on is filament consistency, and also try to only use the material types that the printer gets from commercial suppliers.

If I may, what process did you use for taking your extrusion process and cooling the output to wrap on a reel?

recycled filament has been successfully done for years. I think some college kids in Taiwan had a shopping cart with a shredder, extruder and printer in it making things.

regarding parts, nozzles are less than a dollar now, and my last extruder was $7USD with free shipping from China.

You wont mess up your extruder with dirty filament, the most you will is jam a nozzle, and thats a cheap but time consuming fix.

You can google the Filastruder project and they can help you better than the forum here re-hashing things that have been answered in the other groups.

@emmsclaire, during my PP headquarters visit, I saw / held in my hands a typical jam glass jar with a 3D printed handle. Guys mentioned it is made of PET. Also they showed a ball bearing set, quite rough, but working and the filament itselt. See the photo.
Made by Precious Plastic Greece (as I was told)

Does anyone have experience with using the extruder to made 3D printer filament? I’d love to see if people have been able to get consistent thickness filament and actually use it in a 3d printer.

Good reply @4x4samurai. I think this only illustrates that open-hrd/software 3d printers have huge advantages.
If you want to use a printer without knowing much about it AND high quality support: use closed soft/hardware brands.

as soon as you want to experiment and learn, use open source models.
It’s not that compliacted: a 3D-printer is just a glue-gun that melts plastic in the right spot. The high tech is in the software and firmware, but the hardware is just motors and melters. So get a prusa, or a kodama trinus like i have, and tinker away!

I would just like to state a warning. The cube 3d 2nd generation costs $249 + shipping to replace the extruder. The davinci pro printer costs $99 + shipping to replace the extruder. The Makerbot costs $199 + shipping to replace the exturder. Also depending on the machine you have to re-calibrate the machine for a large temperature adjustment. Ex: printing at 220C for abs then switching to 130C for HDPE requires z height adjustment. I work for a college and nobody gets to make adjustments to the machines because there is to much risk for it to be damaged and then the college has to pay my hourly wage plus cost of parts to repair it which gets very expensive. Also as a hobbyists we upgrade our printers using common open market parts where the college uses the much more expensive manufacturer replacement parts.

Also you will have a problem with most premade printers because the firmware will not allow for much adjustment. Some examples are our makerbot can only print in pla. Our Davinci pro can accept different plastic but the temperature is limited between 170C and 230C. Neither printer’s firmware will allow the temperature to go low enough for HDPE or high enough for PET. You will need to find a printer with open firmware.

I like the idea of using recycled HDPE to use in 3d printers and it can be done, but I suggest getting your own machine that you can tinker on.

Good experiment. The only thing you can really “break” with wrong filamnents in a printer is to mess up the extruder:
Break it, clog it, get it jammed or whatever.
repairing this is usually cheap; a new nozzle some 20 EUR, brand new extruder some 100EUR.

How to mess these parts up?
* mixed materials with different melting points will clog the extruder
* colourants and other impurities can stick to the nozzle from the inside and clog the extruder
* some plastics need to become hotter to melt than your printer can handle (most printers have a temp max of about 250degrees)

As you nust be aware, HDPE has a nice melting point of about 130degrees C:
your printer should easily handle this.
For PET, 260 degrees is somewhat hotter than cheap printers can handle but you can try.

So yes, you can break the printer and leave it unusable for some days, but the damage is never catastrophic and usuallky both easy and cheap to repair. It just costs time and frustration, but is a good learning experience for disassembly 🙂