Think Globally, Build Locally With These Open-Source Recycling Machines

Walk on almost any beach or look on the side of most roads and you’ll see the bottles, bags, and cast-off scraps of a polymeric alphabet soup – HDPE, PET, ABS, PP, PS. Municipal recycling programs might help, but what would really solve the problem would be decentralized recycling, and these open-source plastics recycling machines might just jump-start that effort.

We looked at [Precious Plastic] two years back, and their open-source plans for small-scale plastic recycling machines have come a long way since then. They currently include a shredder, a compression molder, an injection molder, and a filament extruder. The plans specify some parts that need to be custom fabricated, like the shredder’s laser-cut stainless steel teeth, but most can be harvested from a scrapyard. As you can see from the videos after the break, metal and electrical fabrication skills are assumed, but the builds are well within the reach of most hackers. Plans for more machines are in the works, and there’s plenty of room to expand and improve upon the designs.

We think [Precious Plastic] is onto something here. Maybe a lot of small recyclers is a better approach than huge municipal efforts, which don’t seem to be doing much to help.  Decentralized recycling can create markets that large-scale manufacturing can’t be bothered to tap, especially in the developing world. After all, we’ve already seen a plastic recycling factory built from recycled parts making cool stuff in Brazil.

Thanks for tipping us off to this, [Axel].

29 thoughts on “Think Globally, Build Locally With These Open-Source Recycling Machines

  1. I love the idea behind this. However, I was a bit disappointed to find that the plan for a shredder requires buying a large box of laser/waterjet cut parts. Not sure just how easy that is to do in all corners of the world. It’s certainly not cheap anywhere. Was hoping for something a little more rustic using more recycled/re-purposed parts. Hopefully, this is where the community will come in and suggest ways to simplify using more available parts.

    1. I am more concerned about how they automatically sort the different types of plastic as you cannot mix most of them together for “reuse” without first sorting them out (and ensuring there isn’t other contamination).

      1. I believe this is not a problem, and also that it is something that is advantage of decentralized recycling over centralized, industrial-scale recycling of mixed jumble of heterogeneous polymers.

        Similar to mushroom-picking skill (but with less dramatic consequences of false recognition), the issue is solved through experience of the local recycler.

        After a while you learn what types of common plastic garbage that turns up in your local environment can mix, and which ones “spoil” the batch but fit together into another bin. You recognize them by brand (those are mostly common product packages), or by reading labels, or, after a while you develop a hunch of what goes where, based on its appearance and the “feel” under your fingers.

        1. I used to work in a plastics recycling plant, you learn to separate the diferent polymers by experience.
          Soda bottle caps = PP
          Soda bottles = PET
          Most plastic bags = LDPE
          Cable insulation = PVC(flexible and porous) or XLDPE (Stiff and non porous)
          Solo cups = PS
          Blister packs = Rigid PVC

          Also: when in doubt. Burn it!

    2. No one is forcing you to fabricate those parts via laser water jet, that was just his recommendation. With enough patience and a steady hand I’m sure you could fabricate those with a drill press, an angle grinder, and a metal file (which is as much as you can reasonably expect from a basic shop). If you are those constraints, I’m sure you could do it, however, most people are willing to spend a few hundred and send it out instead of trying to fabricate these parts by hand.

      1. Fabricating those by hand is technically possible and I might be slightly biased but why in the world would you want to? Cutting high(ish) tolerance hex shaft holes would take you many, many hours and needs to be done correctly. The housing isn’t quite as tight but you would need to accurately drill everything out to fit bearings and other parts. If you really want to go cheap on this, use a CNC plasma cutter. It will have a bunch of dross / slag and dimensionally it will not be quite as tight but it should at least work and should be reasonably affordable.

    3. Thing is that many of those corners of the world may not have enough plastic coming in and may not have a need for anything made with this recycling process. In such places reusing the and re purposing the plastic products they do get may be the best way for them to recycle plastic. That or burning it to provide heat if when heat is needed

  2. I tell ya what’d be super awesome. If there were a low cost way to make injection moulds and a proper injection moulding machine. Then this sort of thing would be much more useful.

    Melt and shred the plastic? Check. Turn it into cloggs, cups, hooks, dog toys? Not quite.

    1. Some people have been seeing success with some types of 3D printing and DIY injection molding machines for several years now. It is possible, though the results are not on par with traditional aluminum or hardened steel molds (one or two to maybe a few hundred parts per mold instead of 50,000 to 200,000+). Cycle times are longer, if your mold is not metallic.

    2. the injection molding process often happens under very specific temperature and pressure profiles, i doubt it will ever be possible to create a “cheap” alternative when most require a hydraulic piston capable of several hundreds of tons of pressure.

      one might be able to built something that works, but it would be very limited, most likely mold specific with a very long re-calibration process.
      it could take days to figure out what profile a particularly complex mold should run with with a particular plastic, the less complex ones still take quite a few hours, they need to run for a bit between adjustments to see the results.
      the clamping pressures in the machines used were often several hundred tons and the temperature profile used not only the heaters in the injection path, but also water heating of the mold itself, which would then switch to cold water once the injection was complete to increase shot speed and part precision.

  3. This is actually really amazing, though some of the steps are likely to be a bit challenging without access to a machine shop or a lathe and decent drill press or mill.

    I would love to see some kind of method of detecting when the shredder seizes up (say a large metal chunk were accidentally put in). It seems to have no means of stalling out or detecting this has happened at present, which could lead to major damage fairly quickly. I know this machine is designed to only process plastic but most commercially available systems have this type of functionality.

    1. An idea about that. Monitor the spin on the shredder motors. Measure the RPMs while it’s working correctly and fed adequately compare against running average.

      Spark gaps make a pretty good shutdown trigger when electric motors become jammed. Takes some adjusting to get your gap just right so it doesn’t trigger during normal operation.

      Heat it another good indicator of a motor jam. Try holding a rumble pack motor in your hand while powering it. They get hot really fast when you provide too much resistance for it to endure.

      Magnetism is another indicator. During normal operation the magnetic field of an electric motor is relatively stable and compact but with significant resistance it’s less stable and compact.

      Perhaps just a good clutch on the motor. Simple solution that doesn’t require something that varies as much as the above ideas.

      I hope you get the picture on my line of thinking. Look at the motor and determine what about it goes off when it’s jammed. Measure for that and you have your safety system.

  4. Looks to me this an exercise in comparing apples to oranges. At the municipal level recycling is is mostly about separating recyclable material according to type Paper products go one direction, glass another. Metals go their own way Plastics into another to be separated into more streams according to the type of plastic. Scale has to play a large role. The companies that actually reuse the plastic have to have a dependable supply of waste plastic. Without central facilities where the waste is generated I doubt recycling could be financially feasible. Certainly wasn’t financially feasible when there where multiple recyclers before, except for scrap metals ther recycling wasn’t happening until larger municipal operations could generate a steady flow of product to those that could reuse the material. What we see here is mostly a cottage industry, that depends on electrical power to create marketable products. I don’t have prblem with that, but pleaes don’y paint it to be more than it actually is, because it’s unlikely yo remove very much plastic from the wast stream. In the event municipal operations weren’t at the very least reducing the flow to landfills they would be shutting down. The market price of petroleum plays a big role in the profitability of recycling plastic.

    1. It might have more impact than you might think. We have recycling in place here, sacks inspected for suitability of contents etc. And we’re NOT allowed to put plastic in the recycling, it has to go in the black landfill sack because our recyclers have no tooling to deal with plastic recycling and its not in their contract to do so. It breaks my heart to put plastic in landfil but I can get fined if I don’t and it doesnt make sense to do so if they can’t cope the other end. We run fdm printers and closing the loop on producing the filament would have environmental benefits.
      This is in a municipal dept in mainland France, which if you read political statements is a hotbed of environmental legislation, but only apparently when it buys votes and is in the public view…

    2. Certainly plays a huge role in this stuff. Having worked a recycling job, I’ve seen first hand just how much recycling is reclaiming as well as how profitable it is. After seeing that I have to question the business sense of any business that goes through a lot of plastic or cardboard without recycling it. All these fast food places around without a bailer to toss their cardboard in are wasting a busy day worth of money every week. Saddest part about cardboard bail in particular, I live in the city where the stuff is bought up and sent out yet I see only a handful of stores that own a bailer.

  5. He says you can make some components from allot of materials, like metal, wood, plastic, or lasercut.
    I’ve never heard of a material named ‘lasercut’. Where do you find it?

  6. It astounds me how many people in the hackaday community post questions and comments without bothering to read the material, or to watch the associated videos.

    If they had only taken the time, many would learn that their questions have already been answered, and their earth-shattering ideas have actually been implemented.

  7. This looks like a great set of Maker tools to me. They are all on my wishlist now.

    I’m not so sure about all this distributed recycling save the world stuff though. When you consider the size of the problem, all the TONS and TONS of plastic that is needing recycling; I’m thinking that large industrial machines would be more efficient. If we had shops on every street corner that recycle plastic that would be great for reducing the amount of waste but how much electricity would be used powering all of those machines?

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