Human Power Shredder V2


This video is a follow up from my previous shredder design. By using a 1:5 chain and sprocket system I have been able to achieve relatively easy shredding with the use of human power.
Hopefully the video gives an understanding as to what I did to achieve this…

I have uploaded the sprockets that I have created for a mountain bike chain here:

Input is greatly appreciated 🙂

Good opportunity here to measure the minimum torque required by the shredder. Can you try hanging weights off the handle (when horizontal) until it’s _just_ enough for the teeth to pierce the plastic?

Hi @jubo

Sorry for the slow response – totally missed your question!

Thus far, the thickest I’ve been able to shred has been 3mm HDPE… it took some muscle and my machine took a bit of a beating, however nothing too big to fix 🙂


I like your mind, I have been thinking the same thing. However, in Dominica finding one of these is trick. I will continue to work on this (because my arms are getting sore) and post any updates I make, once I find one lying on the side of the street.

In other news, we took the hand-cranked shredder to the beach yesterday to recycle plastic collected during a beach clean up and it got a lot of attention!

I’ll get onto creating a new thread, I just wanted to make sure I contributed to the growth of your invention!

be cool if you could attach this to an exercise bike or rowing machine, would help people to exercise as well as recycle

Holy moly @rorydickens… your machine looks like a beast! Makes me really happy to see another rendition / improvement. Nice and beefy, definitely a step up.

I also experienced a bit of trouble with the final connection to the shredder axle… the force would either break the coupling or pull the axle off-axis and mis-align the blades.

I love your homemade bearings and adjustment screws 🙂 great touch…

You should maybe start a new topic with this version of the shredder… it would be a shame to lose this info amongst a mess of comments… and it might make it easier to follow up and post about the wear and tear.

Keep up the great work!

@timslab Thanks for inspiring us to build something similar.

Hey All,
My team at Recycle Rebuild took this design and made it with an increased number of recycled materials (minus the shredder and bearing) (maybe we call it V2.2?). We did this by swapping out the laser cut gears for used motorbike sprockets and chains, bringing the cost down significantly. Each set is a 1:2.5 ratio so we used two. To ensure the chains remain tensioned we have added little bolts to tension the chain. Almost everything is welded, however, a lot could be bolted.

Our weights on the end of the flywheel are also recycled from old truck leaf springs. We also compacted the design down to what we felt was the smallest we could make it using this approach.

A quick list of stats:
Flywheel Diameter: 97cm (38″)
Frame Length: 102cm (40″)
Depth: Bar width plus the size of the shredder. 26cm (10″)

Our Challenges
The only challenge that we had mostly limited I suspect to our location (Dominica) is that the final sprocket that connected to our steel hex bar would always break. It is the connection with the most pressure. We tried a bolt lock, it stripped the bar, we tried a key it stripped the bar further. So we welded fully.

The machine is very powerful, and a strong person behind the handle can apply a lot of pressure. So far we can do most PET bottles, (but struggle a little on solid blob sections and have no problem with HDPE caps and other similar items.

It is my full-time job to help Dominica develop its socially run recycling industry and my passion to help the PP community. So any questions you have on the machine or any dimensions you need I am always available to help.

Hi @timslab, this machine looks really great. Did you already try to shred thick/ harder types of plastic? Would be great hearing from you!

@timslab the heavier the flywheel the more it takes to get it started, but the more you need to stop it again, thusly making it less likely to get jammed.

Well done @timslab

Looks very good!
You probably have some body building mussles now 🙂

Keep going

The extrusion machine can probably cope with long strips, the screw will just bite off chunks, but if they are too long they will clog in the hopper.

Yes. Good point.
I was thinking about cutting Plastic 5 Litre Containers into thin stripes, and then putting them into Extrusion mashine.

But then i realise, there must be a teeth to tear apart thinks.
I don`t know do plastic get sucked inside this blades, or it will just slide and jump.

Those are very thin blades such as used on paper trimmers. They don’t have teeth and are not very strong. They might be able to cut plastic bags into strips, but probably nothing else. They have bevels on both sides of the blade, so wouldn’t work effectively in a ‘scissor’ configuration, but they are VERY sharp (like a razor), though I doubt the edge would last long.

Ive got idea about using leather cutting knifes.

Title from aliexpress
20pcs 45mm Rotary Cutters Spare Blades Quilters Sewing Cut Fabric Leather Vinyl Paper Rotary Cutter Blades For Olfa/Dafa/Fiskers

Can it replace blades for Plastic shredder?

Thank you everyone for the input… @pe-trhlinka, once everything is ready to go, you can actually shred quite a bit by hand… and the original goal was to enable smaller scale recyclers or people without access/funds to be able to shred and at least add a bit more value to the plastic they collect or aim to use.

you can use 12 20lb(10kg) gym Olympic lifting weights

Question : can we replace the large flywheel with many smaller ones to make the design a little bit compact ?

I don’t know why I feel so proud watching the video ^^. Maybe because it actually works and it allows to replace the motor with nearly nothing 🙂

Would be much adequate for daily work if it can be properly geared with a bicycle, ideal for people who want to shred plastic while enjoying some biking 🙂
this is also good for events and workshops where people come and shred plastic using a bike.

If I get the necessary parts I’ll definitely try it 😉
Good luck improving the concept 🙂

This looks so good @timslab , in terms of output, I know that using a motor is much faster but how much plastic are you able to shred with this setup per hour? I know that it´s physicaly demanding to shred for a full hour but for a hobbyists who want the shredder as cheap as possible and doesn´t need to shred 100 kg of plastic every week this could be great solution right? Thanks for the answer

Great work. Fly wheels should be used alot more for assisted power systems.