Low Cost 3D Printer Waste Recycling - Updated

Written on February 4, 2024

Finally a use for all that waste!

Having owned the 3D printer for 6 years, I had amassed a lot of waste from failed prints, I had always hoped that someday I could re-use it, I wasn’t sure how this could be done, so I did some research.

The most common filament used in 3D Printing called PLA is sometimes sold as biodegradable, after some research I found it is biodegradable but only in certain circumstances like an industrial composting facility where temperatures are over 60°C and even then, it takes a long time, its not really something a consumer is going to be able to achieve at home.

I found that trying to melt it back into filament is a complicated process, so I haven’t tried that yet, there are companies in the US that recycle printed wasted back into filament, but I believe the profit margins for it are so small because it requires expensive industrial shredders, and you can’t sell the recycled filament for too much as after all its not made from virgin material.

Taking into account these points I decided to try and recycle the filament.

I saw that some people have melted it into silicone moulds, and I like that idea, but I first needed to get my waste into smaller sized pieces, I came across this idea of using a handheld planer mounted upside down with a DIY chute around it to make a low-cost shredder, so I decided to give it a go.

At the top is a picture of the successful moulded skull, Pretty good right!

Shredder Setup

My shredder setup consists of a cheap £35 Handheld Planer (Link for people in the UK) with a DIY frame and chute mounted around it with a push stick to force parts into the blade, I also 3D printed a 90 Degree dust port pipe to direct the shredded pieces into a bucket that hangs from the frame.

The reason I didnt design it exactly like the Instructables page is because I thought that design limited the size of parts that could go through it, I tried to fix that in my design, I got someway towards that but I think more can be done.

I guess it’s possible you could print the whole thing but I’m not sure about strength compared to wood and also I have loads of spare wood and not loads of spare filament.

This is what the inside looks like, the slopes are at 30 degree angles.

It shreds stuff pretty well, huge parts dont fit but a lot does or can be broken to fit, here is a video of it.

The shredder output isnt amazing but the pieces arent too big, its good for the price.

Mould Setup

For melting the shredded bits into a mould I use a toaster oven that I got off FB marketplace for £10 as I don’t believe it’d be very healthy to melt plastic in my food oven.

Note: If you plan to replicate this, please use the oven outside like I did, it stinks and smokes a lot, the smoke maybe could be avoided if you’re more careful.

The parts are put into a mould like so and put onto a tray in the oven, I had the temp set at around 200C and make sure to only use the bottom heating element, having the top one on caused it to burn the filament.

That’s basically it, I managed to produce the results seen at the top, I’m really happy with the result, Im probably gonna try other moulds and maybe refine the proccess.

I got the mold from Hobbycraft which is a UK store.

Updates

Update 21/5/2024

I have now also printed a funnel to get the shredded waste into the moulds easier without it going everywhere, I got the file from here.

Update 28/2/2024

Sometimes big bits still manage to get through the shredder so I have now prinred a sieve with 1cm holes to filter out the big bits.

I got the customizable OpenSCAD file from here.

This gives a more uniform size of shreded bits which makes it easier to put into moulds, the rest can go back through the shredder.

Update 6/2/2024

I have now printed a flat 3mm thick “shelf” for it, I believe this will alleviate the issue of stuff flying out. You have the shelf in to start, put stuff on top of it, put the push stick in, turn the shredder on, then pull the shelf out, the stuff will fall into the blade and the push stick should keep it from flying out.

Possible Improvements

  • The melting process could be improved to shake the mould while its hot to try to eliminate the air bubbles seen on the finished piece.
  • There is also the option of buying different silicone moulds to create a wide variety of things from the waste.
  • Another idea that the shredded waste could be used for is as a filler material inside of new 3D prints to give them a bit more weight, which can be useful for certain models.
  • I also briefly experimented with melting the waste into a sheet of plastic which then could be used to make drinks coasters or maybe even guitar picks.

Safety

Just a quick note on safety, a shredder is a dangerous machine and the way in which I made one could be said to be even more dangerous, I made sure to keep my hands well away from the blade and wore face protection while operating the shredder.

The way in which the chute is designed makes it so you would have to put your hand quite far in to get anywhere near the blade and the use of the long push stick adds to this.

I also had a quick way of turning it off should it be needed.

Any Feedback is welcome.

Link to the Printables page with the files, although they are specific to my setup.