Smaller machines

Would it be viable to make the machines smaller?
Tabletop injecton and bucket size shredder?

Stuff that can be transported in a small car, or on a bicycle.
Shredder based on motor of a scoot mobile? Is that strong enough?
What other small motors can be used?

Fellow recycler

Take a look at 12V Windshield wiper motors and even starter motors for a lot of power. Windshield wiper motors are cheap readily found at any automobile recycler or even new from any vehicle spare parts trader. It does not matter what brand of vehicle because they roughly use the same specs.

I hope this helps.

A power seat motor from a car would be a good option. They are in the 150-200 rpm range and have a stall amperage of around 25amps.

The torque needed depends on what you’re shredding, but I don’t think I’ll need more than 40-50Nm max. for all types of plastic bottles. (I posted some torque measurements in another thread).

The rpm just needs to be slow enough to generate the required torque, plus some margin of reserve, from whatever power motor you have. Too fast might cause material to bounce off the cutters instead of catching. You could use a low power motor with a large gear ratio to generate the torque, it would just run a lot slower, but I don’t think this would really be a problem for a non-commercial venture.

The wheelchair motors I looked at were 24v from standard one-person wheelchairs. I don’t think the gearboxes are strong enough to use them alone, even for this small shredder. Of course bigger electric vehicles will have stronger transmissions, but may also have unwanted extras such as differentials. I don’t think speed control is really necessary and is an extra complication.

A problem with low voltage DC motors is that they draw lots of current, which means either high capacity batteries or a large transformer.

@andyn how much torq is actually needed for this small shredder?
And what is the ideal RPM?

Those wheelchair motors also need a 48V power supply and driver electronics so that’s a lot of stuff that can break, but it has the advantage of speed control and lots of power at all speeds.
If it can carry 2 people from A to B then a small shredder seems not to be a big task.

All I’ve spent so far is about 65GBP on a sheet of 6mm gauge plate and two allen keys, but I have spent a lot of time cutting and machining all the parts myself.

A windscreen wiper motor won’t work, not without further reduction that would make it extremely slow.

I also looked at wheelchair motors which I think would be borderline, would probably be ok for light use, otherwise again would need further reduction.

@uaneme correct. I just wanted to point out that a smaller shredder would end up looking like the “mini shredder” from filamaker, but I don’t recommend anyone to purchase it.

From the looks of it filmmaker only wants to sell to companies who can provide a tax number. And their price is a bit high.
370Eur excl. Tax excl. Shipping.
And not even a motor? I don’t know the price of the gears and laser cost. But for 370 I have seen a few woodshredders with motor, hopper, warantee, etc… But still have not seen how those machines shred plastic

A smaller shredder would be something like the mini shredder from filamaker

Mini shredder

@andyn Probably, yes. 🙂

In what pricerange is thisone?
What motor is needed?
Is a windscreen wiper motor good enough for this?

@uaneme Are you talking about my one? Twin shaft, 17mm allen keys for the shafts, internal dimensions 140x80mm.

@espensales There is a smaller diy shedder somwhere here on the forum, cant find it right now as the site is extremely slow. And the search apears not to be working. Therse is an image of it using hex wrenches as drive axis.

Well, I also thought I’d build a smaller shredder too, inspired by the blueprints by Dave Hakkens. It’s gonna be a tiny 60x60x65mm shredder. I’m probably gonna share the blueprints here.

In my case the plastic gears where stronger then the metal knives

Does anyone have one of these CD shredders?

I haven’t seen any of these as 2nd hand. But if this would be available for say $10 – 15 that may ve a very cost effective way to start


The windscreen-shield motors have a gear reduction built in . Try sourcing one from a widely sold vehicle in your country thats at least 8-10 yrs old :; .
You have to take a look at them and decide which one you want. Fiats, peugeot, toyotas… Anything , and some might also have a rear wiper motor.

@uaneme Be careful though, when I opened the shredder, I found that the shredder motor is actually very small and very fast spinning and uses a gear box to up the torque. This is not as good because with thicker plastic, it causes the gears to grind

Windscreen wiper motors sound very usefull, these are worldwide available on the scrapheap.

Are these motors universal? Is there a ‘most common type’?
This might then be a nice candidate for a small design that can be build by anyone, maybe on a wooden frame? so that no metal needs to be welded?

Plastic shredder starter kit?

I also looked at a paper shredder, but the one I found was a big mess. Bend blades but yeah those paper shredders have more power then I expected

I’m currently using a 5-sheet paper shredder, it’s not the beet for thicker plastics but for water and soda bottles, it works really well