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Table of Contents
Plastic Recycling
The lab has a system for shredding and recycling 3D printing filaments. We're currently set up to process PLA and PETG.
Sorting & Storage
Put your unwanted PLA and PETG prints in the labelled Really Useful Boxes under the workbench in G11. Some geometries are easier to shred than others, so consider the following when deciding what to put in the recycling and what to throw away:
- The optimal object for shredding is something with an uneven shape in all three dimensions and <40% infill. The further you get from that, the harder it will be to process.
- Don't put any item that's too big for the shredder (about 10x10x15cm) in the recycling box. If you can cut it down to that size, do it. If not, it needs to go in the rubbish.
- Anything that can be described as a “sheet” or “panel” - ie, big in two dimensions and small in the third - may be difficult to shred because the shredder teeth will struggle to grab it.
- Don't try to recycle anything flexible, like unprocessed filament or a failed first layer that came off the printer as a flimsy plastic sheet.
If you want to recycle something but the box is full, either do some shredding or toss it in the bin - don't overwhelm the lab with unprocessed recycling.
Shredding
The shredder is pretty simple to operate. Make sure it's plugged in and the drawer that holds the shredded bits is empty (don't worry about the tiny bits clinging staticly to the inner surface). Load a few objects into the hopper at the top, close the lid, flip the switch by the power cable, and press the button on the top.
You should hear the motor struggling occasionally and running more slowly or backwards to clear jams. If you hear the steady sound of a motor unbothered by anything difficult in its path, stuff is probably jammed against the sides of the hopper and not actually reaching the shredder teeth. Press the button to turn the shredder off (DO NOT rely on the safety switch under the lid!!) and re-seat a few things.
Remove the drawer from the bottom of the shredder and empty it into the appropriately labelled “shredded” bin.
Extruding and Spooling
Optimal settings for this process are still being worked out, and there may be some adjustments to the firmware and controls on the extruder and spooler. In the meantime, if you want to try making some filament, check out the manuals on the Felfil website and proceed at your own risk.
Values given by Felfil:
| Material | Temperature (*C) | Screw RPM | Motor Current (A) | Drying Needed | Notes |
|---|---|---|---|---|---|
| PLA | 185-220 depending on formulation | 7 | 0.7 | yes | |
| PETG | 210 | 7 | 0.7 | yes | |
| ABS | 210 | 9 | 0.6 | yes | Safety 1) |
| Nylon | 240 | 9 | 0.7 | yes | |
| HDPE | 200 | 9 | 0.6 | no | |
| HIPS | 200 | 9 | 0.7 | no |
Add raw pellets 40-60% by weight. 100% recycled is also possible, but worse quality, not yet tested in the lab. Coloured filament: add 2% pigment by weight
Run the filament through a spare 3d printer heatbreak to check all of it is not over 1.75mm, which will cause an annoying jam mid-print
Upgrades
To do:
- Figure out how to get the encoders on the extruder and spooler working better.
- Add another fan to the extruder to cool the motor directly.
Log
2022-04-08:
- Filament shredder set up
2022-04-27:
- Filament shredder making terrible screeching noise when it reverses
- One of the fins is bent
- Replacement part to arrive from Felfil
2022-05-11:
- Original fins fixed. Disassembled and bent back into shape with some precise taps from a hammer