Shredder build log – Precious Plastic Vienna

Hi there!

In this post you can see the developement of our shredder from the beginning! Take a look:

I have now passed the point of no return where I bought the majority of the components (based on price), so I decided to start a topic on my building development 😀

(18.03.)The next step will be to sand the parts (1/3 done) and construct (+ weld) the shredding unit.
(24.03.)The next step will be to find and buy a suitable motor for a budget price and to weld the shredding unit.
(20.04.)Next steps: Buy the iron parts for the base(EDIT 23.04.: DONE 🙂 ), weld them, have the stainless steel parts welded and have an adapter fot the motor turned.
(29.06.)The remaining steps are:
– lasercut a hopper and the electronics-box out of plexiglasDONE
– buy a C13-circuitbreaker for my breaker box + have it installed
– add the ON/OFF-button, emergencystopbutton and amperemeter to the shredder
– put the whole thing together
– shred the many many kilos of plastic that I have lying around in drawers and my basement 😀

I’ll keep you updated!

congrats! nice start. Did you laser cut in Austria? That’s a bargain for laser cutting 😉

Quick update/tip:

Don’t construct your hopper out of acrylic glass! Ours broke a few days ago while shredding, we now use a wooden one temporarily and will switch to a metal hopper in the future. Acrylic glass looks good but is just not strong enough to deal withe the forces of the shredder long-term.
All the best!

Good luck with your project. If you start posting the stuff you make on ebay or in the bazar you could easily get enough to pay your workspace rent 🙂

It has been a while since the last update, but many things happened!

  1. I am no longer working alone, we are now 4! ( @peterpane3000 , @plasticcruncher , Alon and me)

  2. We finally have a workspace! In a co-working space we rent some squaremetres to store and use our machines!

  3. From yesterday on we experimented a lot and will do so even more, pictures will follow!

and 4) we will build more machines! (we currently have a shredder and a 38x38cm sheet press) not sure yet what we will build but definetely some form of compression oven. We’ll keep you updated!

@adellokman Thanks! 🙂 Wow, sounds interesting!

@flo-2 nice work man … i’m aimming to make it fully automated and i have some ideas to apply it

sorry for caps 🙂 I’m just reeeally excited, since I worked on this thing for roughly half a year now. Fotos (+ video? ) will follow(EDIT some time in the future)! 😀

@jegor-m actually yes, I do have some updates!
I have connected the electronics (Emergency Stop, Amperemeter and ON/OFF Switch) so basically it’s ready to plug in! I’ve also come up with an idea on how to mount the plexiglass hopper so that I can still remove it. The hopper will be “foldable” because of a hinge. I have also organised some buckets to store the plastic.


got any updates about this sweet machine?
also, have you got the netting under the shredder installed as well??

UPDATE 17.08.2017:
Finally things look near-to-finish like! 😀
I mounted shredding unit and motor to the base after attatching wheels to it in order to make the moving around easier.
I constructed my plexiglass hopper and ordered the final electronics parts.

So I still need to…
– …mount the hopper to the shredder
– …connect the electronics
– …have a circuit braker installed

Aand I bought a heat press which arrived TODAY 😀 First experiments in another topic! 🙂

This topic isn’t listed in the moment. Does another comment change that?Went into the spamfilter 😀

Thanks a lot! Wow, a day to put together? That’s amazing! How many people were you?
If I would have worked full time on this project, I probably would have been able to complete it in under 2 months, however until May I had 40 hours of civil service per week and in June I had to do all the things I wasn’t able to do during civil service. Now in July it should go well, but I NEED someone to help me, because the whole thing weighs 60kg+ and I really don’t want to risk something falling on my toe etc.

After having finished the shredder, I will buy and modify a heat press (the one you use for printing T-shirts to produce plates. Hopefully I can then sell these plates to get other people to use recycled materials (and maybe get some of the invested money back). 😉


First of all, good job. This looks nice and planned well, especially if you were making it alone. It took us roughly a month to plan and gather all the components and managed to build it in one day.

What are you building next?

UPDATE 29.06.2017:

Welding is complete, I drilled half of the holes into the framework, mounted angle irons as feet and mounted the sieve to the shredder. (see pictures) Since the right angles of my iron parts weren’t right angles (obtuse angles) and I didn’t want to flex so much, I just used two spare pieces and turned the others around. 😀 looks good too!

Also, I couldn’t await trying to shred, so I did some testing by hand (wow, the sharpening really makes a huge difference in shredding ease) and this is the result I ended with (for now without sieve).

I’ll keep you updated! 🙂

UPDATE 13.06.2017:

– After a long month of waiting for a crucial part for my shredder, where the supplier sort of overlooked my order TWICE o.O, I am now finally on the finish line and should be able to shred in 1-2 weeks! Yaay! 😀
Today I picked up the small part which is needed for the connection between motor and shredding unit and I also did the first half of the welding! (Second half is up next week.) Also this was my first time welding ever. 🙂
Today I am getting a tutorial on how to use the lasercutter at “Happylab” (a makerspace in my town) where I will cut both the hopper and the electronics box out of plexiglas.

On the last picture you can see my connection between motor and shredder. It basically consists of the shredding axe with a ring on it (the screws you see) and the turned rest that fits into the reducer of the motor. In case you wonder, that ring is able to withstand up to ~500Nm and my shredder outputs roughly 280Nm, so that connection won’t be the weakest link for sure.

Also I’ve reassorted the cutting knifes due to many recommendations to do so and I have sharpened the knifes with a file.

@lukas_lang @norbert-vas

For simplicity’s sake I will explain in German:
Schaut euch das letzte Bild an, das ich hochgeladen hab.
Das zylinderförmige Teil links oben mit der schwarzen Box dran ist der Motor. Der hat 1400 Umdrehungen pro Minute und saugt bis zu 2,2 kW. Daran angeschraubt ist das Getriebe (reducer), das Quaderförmige Ding rechts oben. Dessen Aufgabe ist es, die 1400 Umdrehungen auf ca. 56 Umdrehungen pro Minute zu drosseln. Stichwort Übersetzung i=25 gibt hier das Übersetzungsverhältnis an, in diesem Fall 25:1; d.h. pro 25 Umdrehungen der einen Seite macht die andere Seite nur eine Umdrehung. Logisch? 🙂
1400/25 ergibt dann 56 Umdrehungen als Output bei einem Input von 1400 Umdrehungen. Wenn immernoch was unklar ist, schreib mir gern eine PM 😉
I hope this is helping you out!
If someone desperately wants to know what all that means, I can of course try to translate 😉

Hey @flo-2 may I ask you what you mean with “I’ll do that with the reducer already attached to the motor (can be seen in the pictures) where i=25, so the output will be ~56 rpm.” Maybe you can tell us some more Details about the reducer, like where to buy one (link) and how to connect with the motor.
Thank you so far!


UPDATE 28.04.17:
I connected the electronics ( + switch for direction change) and the motor should work, however I wasn’t yet able to test it properly, because the motor needs 13.2A in normal service but about double the Amps in the first few seconds. Unfortunately that’s too much for my 16 Amp fuse… :confused: So maybe I will need a 25A fuse and an extra plug linked to it, let’s see… 😀