3D Printing With Plastic Cutlery

How many plastic spoons, knives, and forks do you think we throw away daily? [Stefan] noted that the compostable type is made from PLA, so why shouldn’t you be able to recycle it into 3D printing stock? How did it work? Check it out in the video below.

[Stefan] already has a nice setup for extruding filament. However, unsurprisingly, it won’t accept spoons and forks directly. A blender didn’t help, so he used an industrial plastic shredder. It reduced the utensils to what looked like coarse dust, which he then dried out. After running it through the extruder, the resulting filament was thin and brittle. [Stefan] speculates the plastic was set up for injection molding, but it at least showed the concept had merit.

In a second attempt, he cut the ground-up utensils with fresh PLA in equal measures. That is, 50% of the mix was recycled, and half was not. That made much more usable filament. So did a different brand of compostable plasticware.

The real test was to take dirty plasticware. This time, he soaked utensils in tomato sauce overnight. He cleaned, dried, and shredded the plastic. This time, he used 20% new PLA and some pigment, as well. We aren’t sure this is worth the effort simply on economics, but if you are committed to recycling, this might be worth your while.

It always seems like it should be easy to extrude filament. Until you try to do it, of course. Recycling plastic bottles is especially popular.

18 thoughts on “3D Printing With Plastic Cutlery

    1. I don’t do it to save money but I can’t argue that is an expensive option. I’ve only dabbed in pullstruding. I’ve considered other option but finding a good affordable shredder seems near impossible… and if I were to guesstimate it wouldn’t return on investment in the first 100kg or so

    2. Hey let him. Stefan is making his phd in germany (or finished), poor paid 50% job/position and has also a child. He need the youtube money. His channel is about 3d printing, so he deliver some kind of content. If you like it or not, click it for adds, so he gets some euros.

      Happy holiday you all!

    1. Um no, the whole argument about food safety and FDM 3D printing is about the printing method more often than the material itself. PLA and a lot of other materials are perfectly food safe.

      The argument comes about due to ease of cleaning and reusability, with layer lines it can make it harder to clean properly and combining that with the low softening point of some plastics that means they can’t be sterilized either.

      For single use plastics the cleaning method isn’t really relevant and injection moulding produces much smoother parts which can be cleaned more easily with no layer lines or tiny gaps and hence injection moulding is much more suitable for food use than FDM 3D printing.

      1. You also don’t know what additives each manufacturer can possibly put in PLA (or any other plastic), so you can’t be sure if any PLA filament is really food safe or not.
        And in addition, FDM releases very fine particles, which, food safe or not, one should better avoid to eat.

  1. I looked into this type of biodegradable single use cutlery quite a few years ago as part of a presentation for a competition. Knowing what I know now, a lot of their claims are just false or only partially true, the exact same claim that PLA is biodegradable. It is but only in industrial composters.

    You do get properly biodegradable filaments now though but they typically aren’t the best in terms of mechanical properties. PCL is apparently one.

  2. How about making filaments from old garbage bags? are there any other ingredients you can add to change the final characteristics (color, transparencies, temperature, surface texture (in final part))? Stuff like that. Dude, you have all the things necessary to operate a complete 3D printing Research Laboratory. You could approach 3D printer companies to do various engineering research, and make a truck load of cash. Oh, Oh, Oh !! Make filaments out of Nitro Cellulous plastic (watch the heat), and detonate the model made and create Detno-Art. Art made by an explosion. Yeah, watch the heat very carefully. Also try various materials to get different textures in the final part. Dang, you’ve got it going on there. Have Fun!

  3. I always enjoy his experiments, but I have a strong suspicion that this would not be cost effective for the majority of people.

    Putting aside the (rather high) cost of the shredder, the amount of electricity required to do this at home makes me think it’s probably much more efficient to produce filament in factories designed for that purpose.

    Happy to be proven wrong.

  4. Gent, it’s not about the cost. We continue to develop new technology daily in the world while exporting our waste to landfills and 3rd world countries. There is little reasoned why we continue to have 50+ different shape plastic bottles in a variety of materials. Why do we box dry foods and package them in plastics that most cannot recycle. Draw a dam line in the sand people and demand we have 50% recyclable packaging materials only. It is as good a start as any and we have been ignoring it hoping that it will go away.

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