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V4 Shredder Single Axis – [INDEX+BLOG]

This topic contains 71 replies, has 28 voices, and was last updated by  Eric Lotze 1 month ago.

Friedrich friedrich

V4 Shredder Single Axis – [INDEX+BLOG]

08/11/2018 at 22:25

This is the main blog where the updates for the development will be shared and general questions will be answered and discussed. Beside that, there are a few important sub-topics which I will give you an overview in here:

First a short overview about certain Sub-Topics of the development:

Drives (Motors and Gears)
Cutting Technology (Shredding principles and fine tuning)
Feeding System (Hoppers, Conveyer Belts, new Systems)
Control System (Electronics)


So here the Development Blog starts:


Hey community,
I’m Friedrich from Germany – a Industrial Designer and Engineer. I will work on the next revision of the Precious Plastic shredder in Eindhoven until the beginning of the next year.

As most of you know there are some things about the shredder which can be improved to build a more reliable/productive and safer machine. The recent weeks I ran some tests with the current shredder, a fast-spinning shredder and a double axis shredder to compare them against each other.


Some points which we are sure we want to improve:


Right now we have a max output of ~10kg/h – to run a workshop or small business with our shredder we need at least 40-50kg/h. The goal should be to shred in half a day (or less) the complete plastic for a week.



The next version should not jam that often as the current shredder does. This is not just a problem of the motor power only but also concept related. Furthermore we want to implement automatic reverse (Torque detection) and back to normal operation.

This is very related to the topic of reliability, due it is not possible to build a save shredder if it is not processing the input material in a reliable manner. The shredder should run without any correction of the user during the shredding process. The shredding blades must not be accessible during the operation, this is ensured by mechanic constraints or sensors.



Some of you report a fast wear down of the shredding blades. The new version should have a way to reduce the necessary time for maintenance and changing of blades. I will try to increase the lifetime of the blades by optimizing tolerances, cutting angles and material selection.



The revision of machines will come with a guideline for a easier part-selection process depending on personal needs.



So how will we start? 

Our biggest problem right now is the huuge variety of plastic we recycle – small/big, thin/thick, flat/geometric and different materials. And most of the shredders are specified on one particular task. E.g. slow running Granulators to recycle runners of the injection process.


I found a different concept from our existing one which i want to adapt to a smaller size shredder. I think it can solve the problem about the big variety in the best way. The biggest benefit of this shredder type is that, the process is more reliable and you can throw in even bigger rests of plastic like left-overs from the extrusion machine or half injected parts.


Its called single shaft shredder which looks like those ones here:


Of course our shredder will be a bit smaller 😉

The build will be similar to the current one (stacked blades on a hex-shaft) – just the blades will be between 10-20mm thick, to assemble the teeths on them. The width will be the same for all, but the length will be adjustable to your needs (education vs. production)


What do you think about this concept?

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06/02/2019 at 21:20

Let me say that I love the creativity of the brainstorming process. Great ideas here for the shredder mechanisms.
That said, @brettc post was eye opening. Looking at that Aliexpress vendor, they appear to have a shredder that meets many of the V4 goals for $1000 USD delivered to your port. https://www.aliexpress.com/item/Easy-use-plastic-bottle-crushing-machine-shredder-grinder-crusher-shredder-plastic-price-plastic-crusher-price/32851194919.html If that works, building a new machine from scratch may not be worth the effort. I view the PP project as developing an accessible recycling workflow. If one of the machines is already available at a reasonable cost, it is worth investigating. At least obtaining one (or finding someone who has one) and using it as a benchmark for the inhouse development seems like a reasonable path. It may be that the final answer is the modification of one of these machines for different power source, or for cleanliness, etc. It is difficult to develop a lower cost machine that does the same thing as a low cost off the shelf product.

Perhaps the Aliexpress machine is a piece of junk with low reliability, or the vendor is not reliable, or some other problem, but it does set a cost benchmark for a machine of that size

07/02/2019 at 09:06

hmm good point @cgoflyn since we never ask people for feedback before we start a new version, like really never.  After that we always keep our plans super secret, so no one that helps out has a clue what we are going to do. And obviously during the development process nobody can see where we are up to every month, making it impossible to share suggestions. Because we really don’t want people doing that.

But to be fair. YES we actually do have a filter. We listen carefully to committed members, with a real profile (not 5)  that share constructive feedback in a proper way.

07/02/2019 at 10:14

A professional shredder price in my country is starting from 10 K euro.
If V4 will cost 2-4k i think it will be a great achievement. About Aliexpress and Alibaba, i think we all know the stories and the quality. I know somebody with a experience with a Chinese producer and this one provide the product at what quality hi desired – more money better quality, low budget – nice junkie.

Don’t stop and don’t be disappointed. You will not be able to thank everyone. Whoever wants to improve their product alone.

07/02/2019 at 13:27

@euromarketo, if you search auction / ebay  / craiglist for ‘plastic granulator’, you can see the range for shredders is 2-5 K. no matter what you have to say about ali-express : a larger manufacture gives you 10000% more for your money. they have solid and pretty cheap supplies and sometimes decades long record to build such machines for and with their clients. it’s unthinkable that a guy in a garage can build the same value for the same price.

@davehakkens, I am happy to see that you finally discovered some basic about community building, so when can we see the first polls ?  And sorry about the accounts, wasn’t really aware that credits is more important than substance here 🙂

07/02/2019 at 17:17

@davehakkens, I think the major problems lies in your way of thinking about the project (see Stan’s comment : i fully agree since it’s 100% backed up by users I had to deal with).

It would be nice if you seek for professional advice, or gain the needed education to build PP as network, flat and of horizontal structure. Enabling the network to grow (see bazar fees problem) and giving the tools needed (see this useless forum software)

Because instead and it’s obvious you’re more busy with building the ‘Dave Hakkens’ brand or pyramid/monolith instead of doing good for everyone involved or at least recognize what’s actually going on with the folks around here. It also looks that anything which doesn’t pass your imagination or doesn’t fit in your box (or mattia’s ) won’t be implemented, supported or sponsored or developed. You can’t be manager, machine builder or designer at the same time. This [email protected] is also another prove for that.

So yes, please find somebody who can advise you in such things; there is a cirtical mass waiting to be boosted. You have received all the funds for that, so please use it for that. Needless to say PP has been a community effort.

what’s required :
– free trade
– budgets for projects (remote, not in f** Eindhoven)
– software to enable networking (what you gave here is just a rotten piece of crap, sorry)
– user – workspaces / show-rooms / bazar
– extendable machine component/catalog
– full transparency: network stats, google analytics, ….
– professional skill sets within the administration – department (replacing you and mattia, please)
– pure community driven decisions, for real.

these things you can find always in open organizations/networks.

07/02/2019 at 17:42

@cgoflyn  that rant was off topic and a bit unnecessary, please start a new thread and refrain from this kind of trolling.

07/02/2019 at 18:28

yeah, a I am sorry about, i didn’t really start this, I, we just reacted 🙂

15/03/2019 at 13:10

We made some improvements this month about the cutting technology and started to build up the basic advanced control system for the pneumatic piston.

For now the output looks already promising. We have to continue to improve the reliability of the operation, redesign the blade inserts and the way of how the inserts are shaped and clamped.

Thicker PP material from our sheetpress is a bit challenging for the moment, but we think that the redesign of the cutting unit will solve those issues.

PS CD Cases: 13,1kg/h (old shredder: ~3kg/h)

PS Random Geometry: 9kg/h

PS plates ~10-15mm thick: 13kg/h

PP DVD Cases: 14kg/h

So considering that we are operating at a shredder-with of 1/3 of the full size, we are on a good way to reach our goal of an 30kg/h average.


Beside that we started a second shredder design of a double axis shredder. We want to know which is the most efficient solution (labor/energy/output) in our small size shredders (compared to the ones used in industry).

You will hear about that as soon as the first CAD design is done in the next weeks.

25/03/2019 at 16:10

We are a prototype engineering company in Johannesburg. We just designed a double axial version with the same concept as version 1 shredder but with 3 teeth per cutter. Also we bad the tooth much shorts to the axis of rotation to generate more torque through the cut. we are using a single phase 2.2Kw motor that controlled by our in-house controller that detected when the motor spins to slow (lets say 50% if 1400rpm. I measure with a hall sensor at the fan and glue a magnet on the fan itself. the mass of the magnet is to small to induce a vibration. I was looking at the other alternative to detecting a jam by measuring the raise in current with a simple current transformer.

25/03/2019 at 23:37

That sounds really good guys! Do you have more pictures of it? Maybe a video?

30/03/2019 at 19:08

There is some development going on at OSE on this as well, so feel free to look there;


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