Getting Shredded Plastic…and Legs

Two men in black shirts stand between a white and a blue exercise bike sitting on a table in front of them. The exercise bikes have black drums slightly larger than a coffee can affixed to the front of the bike which houses the shredding mechanism. In the background is a "Precious Plastics Torino" circular logo.

While electric motors have taken the drudgery out of many tasks, human power has its advantages. [Precious Plastic Torino] has developed a human-powered plastic shredder for those times when an electric motor just won’t do.

Designed primarily for educational purposes at venues where electricity can be difficult to source, but also useful for off-grid environments, this exercise bike-based shredder can take small pieces of plastic and shred them into tiny pieces suitable for use with any of the other machines in the Precious Plastics ecosystem like their injection molding machine. As with all [Precious Plastics] projects, the files are will be open source; however, there is a six month exclusivity period for Patreon subscribers to help fund development efforts.

The build is relatively simple: take an old exercise bike, remove the unnecessary bits, and run the chain up to drive a shredding mechanism mounted on the front of the bike. We think they should’ve kept the flywheel to help keep the momentum going while shredding but can’t fault them for wanting to keep the prototype as simple as possible. Maybe the next step is getting these in spin classes around the country so people can get their exercise and help recycle in their community at the same time!

If this shredder doesn’t suit your fancy, maybe recycle your plastic with SHREDII or this other DIY effort. If you’d rather generate electricity on your exercise bike, then try building this bike generator.

10 thoughts on “Getting Shredded Plastic…and Legs

  1. This is ridiculous. A geared motor would be and easier build, do the work, be cheaper, and be safer. A simple solar panel can make it work off-grid.

    FYI: places without reliable electricity don’t have old exercise bikes to cannibalize.

    1. Perhaps they don’t have ‘exercise’ bikes, but they almost certainly have regular bicycle by the bucket load and the difference between the two is rather minor and easy to fix. The tricky bit here is a shredder tough enough to deal with the plastic that doesn’t require more power than a human can provide to work, not the frame to stick it on. Also in a poorer nation human labour is way less valuable than the electric I’d suggest – you send them your solar gear motor system and they would put a bike on it so the solar can be used for stuff they can’t so easily put man hours into…

      Either way this is really not meant to be practical recycling, it is a demo unit to show a stage of how plastics can be recycled that can be deployed anywhere. And for that being bike based actually makes a heck of alot of sense – you want people to understand how much/little energy is needed for something having them do it themselves via a tool that is rather familiar makes it very much more meaningful.

  2. Nice .. so many companies want to sell you a shredder like this for hundreds .. these guys share the plans for it and provide a practical means to obtain the parts overall. This would be more than enough for a moderate sized 3d printing lab, and is the 1st required step to recycling filament.

    1. Having worked in thermoforming, I can tell you that while the design of a machine like this is simple, the choice of materials is not.

      A few hundred bucks for a similar machine that lasts more than a couple hours? Shut up and take my money.

      The blades alone on the inline grinders we used for our trim scrap were $2000 a piece, 3x per machine.

      Most plastics are way more abrasive than most people realize.

  3. And now, you realize that without electricity, your precious plastics’ flake are useless, since injection machine need way more electricity to heat that plastic that you can provide. So in the end, it doesn’t even matter, you need electricity.

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