Hello community,
I’m Landry, a member of V4 precious plastic, i work on the V4 shredder double axis as you can see here. I work also on the V3 single shaft for make it more stronger, sustainable and easy to build.
So, the first, THE SHAFT:
The BIG problem is the shaft, lot of people broke it, and it can be many reason of that, a stronger output vs diameter of shaft, a material not enought strong, a bad coupling…
So, for explain, if the diameter of the shaft is 20 mm, we need a gear box output torque around 200 Nm, for 25 mm, around 300 Nm and 30 mm around 350 Nm.
Also you need use this information with a normal steel shaft, C45, but if you want use stainless steel, you need to decrease the Torque around 50 Nm, so for the diameter 20, it will be 150 Nm…
It’s an estimation, but if you want make a better calculation, follow this :
Torque (Nm) : 200
Tys (Mpa) (the capacity of a material or structure to withstand loads tending to elongate, you can find it in the google for your material) : 530 (for C45)
Sys (Mpa) : 0,58 x Tys
Safety factor : 1,5
Shaft diameter (mm) : (Torque x Safety factor x 16000/PI/Sys)^(1/3)
And you will have the round part diameter of the shaft.
In the release, i have used a 36 mm shaft with a round part diameter of 30 mm, this shat have 2 thread of M35 each size for put nuts and keep in place the blades.
THE COUPLING :
I use an industrial coupling, Fenner HRC 150 with a continuous rated torque (Nm)600 . You can, use also the HRC 130 if you have a shaft less big.
Both of them use a keyway of 8 mm or 6mm for the 20 mm round shaft
THE MOTOR :
RPM :49 tr/mn1/28,35. 1,5 kw. FS : 1
230/400V. 3,5A/400V. Cn : 273 Nm. Axe : Ø 30 mm x 60 mm
Weight: 38 kg
For the rotation, it’s better to have something between 25 and 55 Rpm, depend the material you want shred, BUT, less speed = MORE TORQUE, so be carefull!
THE BODY :
For the Body, I have used the same system of the V4 double shaft, something easy to build, less part but more strong.
the side are 10 mm thickness and the 2 hole for the bearing will be thread, so like that we stop the dificult chanfer work and we are on the perfect position for have the 2 bearings concentrics.
The sieve is also modify for put it more easy to use.
Also, all the cutting part have holes into corners, so less deburr work.
THE BLADES:
For the moment, i havn’t do anything on the blades, because it works, but if you have some modification or sugestion, let me know.
I will test it in the month and let you know.
  
