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PET and HDPE filament made from (recycled) flakes

Zeth Beato zeth

PET and HDPE filament made from (recycled) flakes

27/05/2019 at 23:58

I’m working on a project trying to make filament from recycled bottles to then use it for 3D printing, so I’ll be using PET and HDPE.

I’m working with a team to build a extruder but just happened to got a commercial one for this project and would love to hear about your experience with this. Have you been able to transform HDPE or PET flakes into filament? What was your setup? How was the process?

I would really love and appreciate your help! Or if you have any links to any source of info!

I will be posting pics as soon as I get the extruder home.


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28/05/2019 at 07:34

Hi @zeth,


Looking forward to hearing more about your project and I’m curious about your extruder.


Just search the forum for ‘filament‘ and you’ll find plenty of discussion about the subject within the community.


As I understand it it’s ‘easy to do, but hard to master’, as in making hobby filament is not that difficult (I believe shredding the PET poses the biggest problem), but if you want to make ‘professional’ filament you’re gonna need to do a lot of post processing (a filament ‘mile’) and fine tuning.


The more information you give, the easier it is for the community to help.



26/12/2019 at 01:41

Hi again and happy holidays!

We’re still working on making filament from PET bottles (we won’t be working with HDPE for now). We’re currently working with Filabot equipment (Filabot EX2, Airpath and spooler) and have performed some tests that I’ll be sharing with you guys. We’re still trying to get our filament out with no bubbles and to be able to 3D print with it with good results.

If you guys have any suggestions or comments please feel free to do so!

1st Extrusion test
The settings used for our 1st extrusion test were as follows:
– Extruder temperature: 225C degrees
– Environment temperature: 16C degrees
– Nozzle diameter: 1.75mm

During the first attempt we realized most of the shredded flakes were really big (more than 1/8” as the maximum recommended for the EX2 extruder)  and the extruder got jammed so we decided to re-shred the shredded plastic.

We also realized the filament coming out from the extruder still had some of the cleaning material that comes with it so this is why it was a bit white. Unfortunately, the shredder used is an old one and doesn’t have multiple blades, so the milled plastic ends up kind of big by only shredding it once.

To be continued…

26/12/2019 at 18:57

2nd Extrusion test
Settings: Extruder temp 245C degrees

After shredding the PET plastic flakes twice we realized they were still bigger than the max. size recommended (1/8”) for the EX2 extruder so we decided to use a blender.

After using the blender the extruder was jam free, the problem now was that first we set up the extruder temperature at 225C and the filament that was coming out of the nozzle solidified as soon as it came out and it was cracking just by touching it, it was not malleable at all.

After increasing the temperature to 245C degrees we got our first -kind of- filament as shown in the picture. At this point we still didn’t use the airpath or the spooler, we were just testing the extruder and pulling out the filament by hand (with pliers actually), this is why we were not able to keep the diameter.

To be continued…

28/12/2019 at 17:11

3rd Extrusion test
– Extruder set temperature: 248C degrees
– Extruder working temperature: ~250.7C degrees
– Environment temperature (A/C): 17C degrees
– Airpath speed: 80%

After playing with settings, we decided to apply some glass wool around the nozzle to minimize the amount of bubbles and the cracking that we learned was because the nozzle was not keeping the (heat) temperature. It really helped us on getting better results.
This time we used the airpath and got best results when it was at 80%. We still didn’t use the spooler, just some pliers and hands to pull it out so diameter was not consistent all the time.

We also did our first test with the 3D printer, just to see if it was possible to print with it, as you can see in the video the quality of the printing was not good. We also started printing a test cube (I lost the picture somehow =( ), it was printing fine but I had to stop it at 10% since the filament diameter was not consistent and would affect printing anyway.

To be continued…

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