Shredder 3.1 Fixes

This is a follow up of the assembly guide and remarks about in the forum. Please consider the scenarios :

  • DIY build, scrapyard components (that’s about ~20% of the users we know) 
  • Professional builds, using new components
  • single, 3 phase and gas motor
  • transmission via sprockets

Please note that this page is old, we continue all new updates here on our new library page for this component.


Shredder – chamber

  • use stronger hexbar (32mm) and driveshaft (min. 30 mm)
  • use solid blocks, min. 10mm thickness (ie: extra laser cut parts) to connect to a frame or base plate (min. 15mm)  
  • extra support material to enforce bearing mounts
  • use UFCL 206 bearings
  • thicker sieve mesh thickness (accidents happened, sieve got into the shredder)
  • height adjustable sieve (cheap solution for improper assembly)

Shredder blades 

  • use hardox, this material is hard to process; it will be hard to grind/file if there are nominal errors
Stability / Durability

Shredder – chamber

  • clamp blades together on hexbar; can be done with nuts but cutting a thread on the hexbar requires a good lathe; welding might be ok as well 

Shredder – blades

  • it might be better to slightly redesign the blades, in a way somebody can grind them without creating too much clearance to the stationary blades
  • grinding a slight angle on the blade tip decreases cutting forces as measured via amperage metering (inverter)  
  • often the blades collide against the stationary blades, leaving the user with 2 options : grind the mobile blades or the stationary blades. the stationary blades could be lifted up from the bottom but it needs a bar acting as set-screw. not just vertical adjustment is needed but also 2 set screws should push from the side against the stationary blades which is easy to fix in the side plate drawings, ideally on both


  • ideally the shredder chamber should have already something in place to mount a hopper because drilling even 3mm stainless can be problematic without a drill press. this can be part of the laser cuts


Frame variants

We encountered so far 3 different frames

  • as designed in v3.
  • compact design (smaller, compact, enable easy sheet metal enclosure, 20% of our sales)

  • minimal : mount all on a metal base plate, easy to ship and has the possibility to get an enclosure (80% of our sales)

Motor – Electronics

Auto – reverse / Auto-stop

3 Phase motors & inverter : 

The cheapest is using a inverter (~120 Euro) which outputs an over-torque / stalling signal at 5-10 Volt. The very signal can be used to implement this via Arduino or analog circuit.

Single phase motor : 

For single phase motors this can be expensive since it requires to operate at high voltage/amperage. As alternative, a cheap sensor with a relay could used

remarks: we prefer always 3phase motor and using inverter since it has all on board : direction switch, speed control, inputs/outputs to enable auto-reverse but also metering.


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