As you might know we are working on V3 of the project, here you can have a look at our full plan. This time our focus isn’t on re-developing the machines but trying to get the most out of them. That said we do have a few tweaks and things we could improve on the shredder. Mainly making it easier for the plastic to be pulled into the shredder so you don’t have to do it manually. And looking for a way to make it easier to change/clean the mesh. This wouldn’t be a full update but more of a hack. So if you already build the machine you can simply upgrade only a component (the advantage of a modular build 🙂
@morrentrading is going to help us with his expertise in building shredders. If you guys have any updates/hacks/suggestions let us know.
Our first try-out. A different blade-set
Hello everyone. We got in touch with Peter Hinten, an engineer from the Netherlands who wants to help out with the shredder update. We discussed about the things that could be improved and he made a new CAD model based on the previous model + feedback. Have a look at the attached .pdf below and turn around the 3D model in Grabcad (click load in 3D viewer to turn the model around.)
What do you think, suggestions tips feedback?
I love the look of the new blades and the design changes look like great improvements! I am curious as to why you did not go with a 3 or 4 blade rotating knife? Every other shredder I can find uses this style. Like the ones below. I am not criticizing, I merely want to understand. The machine is well designed so I am sure there is a reason! Off the top of my head: cost of materials – a two blade knife uses less material and/or rotating mass is less as well, also most other shredders are dual axle and thus more complex – so minimizing complexity. Anyway, I drew up a few blades that would fit right into the current housing. I mostly modified the original design. Any feedback on these would be great! Thanks! Again, love the machine!
That’s correct, there’s a small gap between each rotating and fixed knife, and that’s how it’s intended.
In a perfect world, 3mm thick metal is 3.000000000000000mm thick, in the real world, 3mm metal is something around 3.01mm thick. Due to this, a small gap is required to avoid friction between the knives or having a shredder that doesn’t spin at all.
The Emergency switch is a really good idea, when I bought my electronics I included one, should be positioned for very easy access.
Thumbs up for the frame/leg mod.
The “Knife area is decreased to avoid cutting large part in one time”, does it mean that the knifes are made of thinner steel? That would mean more parts.
Wow, that looks cool.
Thanks for sharing !!!
Have you tried them out? How big and what are the differences?
Do you have CAD-files available for those parts? We are about to order and if these knifes are much more efficient, I would like to go for them of course.
Cheers from Cambodia
If you want a custom shredder axle like this I can make one for you. I sell the standard design in the Bazar, But I have made custom ones for people using different bearings, couplings etc. I think the UCFL205 is a better choice anyway, 20mm is a little on the small side for the shaft for the amount of torque some people are using. Also adding a keyway is a good idea, the plain 20mm shaft can slip easily.
I can also supply raw lengths of 27mm hex cut to length if you want to machine your own shaft.
MOTOR WITH SAFETY STOP
AAA Hi All, I will start to built my shredder in May and I am looking a solutions to make the shredder cheaper and easier to built, The solution I fiond are:
1 aluminium frame without welding
2 Hex axel with round end 25mm for bearing UCFL205 and final 24 mm with keyway to go directly inside motor, no coupling needed.
3 Monophase motor with 750w / 1 Kw max with electronic, double directions, safety stop and variable speed included, double output for shredder and extruder (I found it)
4 Shredder without weld fix end profile (you didi it on upgrade files)
So I would like if anyone can hel me, I need Cad file for the side plate of shredder and round spacers, the side olate must have new bearing holes, now they are for UCFL 204 90mm center to center, I need 99mm, then the 2 spacer has the inside diameter of 20 and I need 25 mm. i am not sure is there are more modification to do.
I’m quite sure it is possible to built a shredder for 800€ with new motor or buy it from a builder for 1200 / 1300, consider that you will use the same motor for extruder so it will be very cheap.
Please feel free to contact me, actually I am in Lima (Perú) but I will be in Italy from The end of March.
Hi Dave! We are a group of basicyear students from the Gerrit Rietveld Academie making the shredder at the moment. The thing is that I cannot find version 2.1 anywhere to download (the precious plastic website is only in v2.0!) Thank you!
any reason that shims aren’t used?
HI, mi name is Luis, im from mexico.
im trying to build the shredder but on my autocad inventor drawing found a gap between the rotating blades and the small and big fixed blades.
the total lenght of the rotating blades assembly is 148 mm
The total lenght of the fixed knifes is 149mm
Taking this in consideration there would be a gap of 1mm horizontally between fixed and rotating blades.
Please let me know if im doing something wrong.
thanks in adavance for your help with this issue
Is 2.1 tested yet ? Does it make sense to change the blade format ?
Hi everyone! I write from Argentina! I am working on a new design attempt for the shredder. I am thinking in somethin like this…
where it is used one or two big blades and a lot of small blades and it is not necesary a mesh. The size of the particles is fixed by the small blade size. Did you already think in something like this?
I am trying to make the shredder cheaper because here in Argentina there are a lot of people interested in start with plastic recicling but build the machines are not cheap enough.
We did. But the material was not always getting into the shredder. The spiral seems to works better but results in jamming the shredder when too much plastic is shredded at one specific spot
Have you tried arranging the blades in a chevron pattern, one half a mirror image of the other so that material is pulled towards the centre?
I read a lot about people having to push material (by hand or with a stick etc.) into the blades. I don’t have personal experience with the PP shredder, but I have built a twin shaft shredder and I have no problems with this, it just grabs anything and feeds it through even though the blades are half the size and the teeth much smaller. I have an interlocked lid on my hopper that only needs to be opened to add more plastic. The only added complexity is that you need a pair of gears to link the shafts.
In the PP hq I worked a lot with the shredder.
I made two improvements:
The hopper is now straight so the material needs to be a bit smaller but therefore it gets less stuck
With the elastic rope you can create tension on the press stick, resulting in shredding without needing to press all the time by hand
With shredding PP we had a lot of problems with the axle connection so we made a coupling of 2 plates welded to the axle of the engine as well to the axle of the shredder. The 2 plates are connected with 4 bolts so it is still possible to take it apart.
Ah! Okey, now I understand 🙂
Good to read your feedback! The amount of knifes is the same, the thickness also. The curve at the end is smaller so it would chew off smaller bits. This to avoid blocked engines and too much stress on all components. The limiting factor timewise is the sieve anyway
Wow, that’s a serious upgrade there! I love it. Especially the safety improvements are great. I’d love to built this one!!
I agree that it would be nice for something on the outside of the blades to grab onto the material. I am working on a new set of blades for my machine and I may give this a try.
Another thing that I noticed with mine is that sometimes material likes to get stuck between the blades and spacers. I’m thinking that next go-around I may add some cuts on the spacers to help grab material and drag it down (attached)
I also agree about the mesh, it gets clogged easily, and on my setup it’s really hard not to not get material everywhere.. So I’m gonna make a hopper that goes underneath, and I’m even thinking I may attach a shop vaccum to the bottom to help draw material through. I found on mine that the material is definitely chopped up smaller than the mesh is, but it just doesn’t want to go through the holes easily.
I’ve also posted an update on my original thread.
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