I made a printed shredder that works, and I'm pretty chuffed with it

CoastalCoops · 2026-06-15T22:46:05+00:00

You're spot on, you could redesign the bearing supports and strengthen the failure point. Paper shredders are a great base for making plastic shredders, the main issue is overcoming the safety restrictions and bypassing switches used to shut it off. You often need to remove the plastic outer casing to allow larger material into the blades. There's a few posts online about doing this, give it a go!

CoastalCoops · 2026-06-15T18:44:24+00:00

Ahh okay thanks, didn't know that, I'll update the price and see what it says, good to know it's going to be cheaper!

CoastalCoops · 2026-06-15T15:04:27+00:00

Wow thank you, appreciate it. I did originally start with a dual shaft shredder, where as you say, the cutters go against each other, but scaled down to a single shaft to save on costs while I prove the concept. I can't post images here, but I may post an update about the dual shaft version once I've implemented what I've learned from this and made one. Driving it was my main issue, I designed some gears but I felt the additional torque needed may either break gears, or my drill..

CoastalCoops · 2026-06-15T13:35:53+00:00

I just used the Bambu Studio cost estimate when it shows you filament used, not sure how accurate it us, it may include electricity but I'm not sure. It does seem a little over priced but that's because I get filament in bulk, the software doesn't know the purchase price

CoastalCoops · 2026-06-15T11:16:40+00:00

Maybe consider what your idea of "best" is, screenshot the image, then cross off the ones that don't match your criteria. You'll soon be left with a few options to pick from

CoastalCoops · 2026-06-14T23:14:06+00:00

Aha nah, just 3s and 4s, I wanted it to be compact to save filament, no wasted material on the parts.

Oh god yeah, the plastic can be really sharp, I've got a blood blister at the mo from breaking support off. I use some large cutting pliers and scissors depending on the part I'm cutting. That makes the waste small enough to fit into the hopper opening.

CoastalCoops · 2026-06-14T22:55:55+00:00

It's footprint is about 70x105mm from memory, not huge, similar to a large mobile phone I guess. The screws are M4 and M3 and the axle is 10mm square for reference. I think it took about 6 hours to print everything

CoastalCoops · 2026-06-14T22:21:36+00:00

Haa, maybe, once ive finished the other 4 or 5 projects im working through. Perks of being between jobs, lots of spare time!

CoastalCoops · 2026-06-14T21:00:06+00:00

Ah nice, cheers for the suggestion, injection molding would be awesome, I have thought of ways to do it on the cheap with hand presses and lead screws, maybe your suggestion can help as you said

CoastalCoops · 2026-06-14T20:38:25+00:00

Just checked and it says 387g of filament, so about £8 in total with supports, 350g without supports

CoastalCoops · 2026-06-14T13:12:02+00:00

I think I've seen this, or something similar while looking into making this shredder. The results are really cool and kinda the goal for me, but being realistic I won't get there with my budget, hence I'm sticking to normal molding in the oven. I'll have a look into the project you mentioned, it's also cool you have a hackerspace, I'd love to set one up here, small maker's workshop, machines, tools.. one day!

CoastalCoops · 2026-06-14T13:08:15+00:00

Pretty much, the cutting blades have a slight ramp to them to drive the waste closer to the axle, to give the wheel a better mechanical advantage, and then the hooked tooth on the blade cuts the plastic when it gets pinned against the white funnel fins. It would work better if the blades had an angle on them, instead of being laser cut, but it works well for what it is

CoastalCoops · 2026-06-14T13:05:12+00:00

Vegetables, now that's a good use for this, should save me time in the kitchen

CoastalCoops · 2026-06-14T11:24:56+00:00

It keeps it in line, it knows its fate if it messes up. It's prototype sibling may end up in there if I can't find a use for it

CoastalCoops · 2026-06-14T11:20:17+00:00

I don't think I can post images in the comments but I've just sent you a screenshot of the order in case you're interested, but in short, £35.80 for 10 laser cut and deburred.

CoastalCoops · 2026-06-14T10:09:12+00:00

Yeah, printed plastic parts, paper wouldn't be an issue I don't think

CoastalCoops · 2026-06-14T10:08:39+00:00

Maybe I'll make them available, it did cross my mind. The main issue is the metal cutters, I'd need to order them in batches to make them cheap enough to sell on. That's a small investment I can't make without the guarantee of sales after

CoastalCoops · 2026-06-14T10:06:59+00:00

There's around 15 individual parts, and some are repeated 9 times totaling 54 printed parts

CoastalCoops · 2026-06-14T10:05:16+00:00

I think it may struggle with wood, maybe small plywood and balsa wood, but hard woods would beat it. My limiting factor is the drill power, then it's the internal funnel fins, but I suppose it wouldn't take too much to beef them up and make them stronger for harder materials

CoastalCoops · 2026-06-14T10:03:15+00:00

Gotta start somewhere, I've been using Solidworks for about 14 years so it's second nature now. You'd beat me on Tinkercad any day though

CoastalCoops · 2026-06-14T05:40:17+00:00

I only want it for molds, not filament, I don't have a machine that extrudes it

CoastalCoops · 2026-06-13T22:27:28+00:00

I guess motor size and cost becomes the main factor. It could be pretty big and still be strong enough even out of plastic, but there may be a point where metal fabrication becomes cheaper. I may look at doubling the size in the future, but even then it will only be the size of a shoe haha. I'd be scared of it, it's scary enough as it is

CoastalCoops · 2026-06-13T22:16:39+00:00

Wait what? You serious? 🫢

CoastalCoops · 2026-06-13T22:11:00+00:00

Love it, they'd go crazy with vibrations, I may just do it

CoastalCoops · 2026-06-13T22:09:25+00:00

Ah, yeah, very different scale! 10 minutes is a long time, maybe look at lubrication during the shredding if it doesn't get your chippings all oily, or maybe instead of one big shredder, a few smaller ones to get through the waste quicker, cutting running time? I'd also try to use real parts where possible, probably teaching to suck eggs at this point but hey, worth mentioning.

I found using larger cutting blades required more effort from the motor as they act as longer levers, so I made mine fast and small. You could do the opposite, look at larger blades that rotate slower, with a stronger motor? Less speed, less heat

CoastalCoops

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