Hi there!
I’m based in South Africa and started a small recycling and lamp design company, I was using the pulltrusion method but for scale its such a pain. The filabot that was shown on this channel is a little (lot) out of my price range so I bought an Artme-3D. The designer said someone managed to extrude PET, but recognises that its not easy and doesn’t officially support it.
The machine is a vertical extrusion machine, so the filament is partially at least calibrated by gravity which leads to not much space for cooling so crystallisation is common. The other potential issue is the screw is quite short being around 14cm (and therefore heating zones) and there is only one temperature control. The article here was super helpful but I have still not managed to get any notable lengths of filament out so I was hoping for some ideas or insights, anything would be appreciated.
Initial runs
My settings are similar to what he had posted from the person who had some success.
- Extruder temp - 255-260C (I’ve tried everything in this range)
- Screw speed - 7rpm - 20rpm
- High compression screw (they ship 2 screws, high and normal compression).
- Shredded and sifted to ~3mm PET from water cooler bottles
I had huge issues with plugging and extruder inconsistently extruding which I had expected from the video but my idea was to make bad filament, pelletise and re-extrude better filament but I saw most other extruders have some type of feed zone cooling, which this does not (https://www.artme-3d.de/produkte/desktop-filament-extruder-mk3/produktbeschreibung-mk3/)
So I added some cooling fans to blow over the exposed metal feedzone after seeing some plugging near the top which was causing the extruder motor to skip. This seemed to help a bit but I was still not getting anything useable.
I did manage to pelletise as whatever strands I had and then tried again, first using the normal compression screw but the results were not great and there was huge plugging again. Then with the high compression (just in case) which also didn’t help.
Below are my pellets, they aren’t amazingly consistent and have been started crystallisation due to insufficient cooling but they flow a LOT better (problem for another day)
And below here is the plugging on the extruder screw
As you can see, its more in the “compression zone” than directly the feed zone and it seems like basically unmelted and the end of the screw is comparably clear of plastic. This has made me concerned that given the very short screw and heater section, I have inadvertently started cooling the “compression zone” which isn’t registering since the machine has one thermistor.
I knew that it would be a struggle but honestly this has been disheartening and I have seen videos of at least something useful coming out of this machine.
Next short term steps are
- Shred and work with another source of PET, potentially there are weird additives in making water bottle jugs since they are comparably thick walled.
- Run the machine without the feedzone cooling fans (long term, add a thermistor to control the feedzone cooling perhaps??)
If anyone can offer any advice I’d massively appreciate it!