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.

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


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!

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.

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.

![](upload://zMw1lYMrXR7Owk2ucRxND9RxL6u.jpeg) ![](upload://lLsevdeKES9yvYmOMGkPNWZz689.jpeg) ![](upload://iOBA9iOB92e3FzfyIyElEaNT52T.jpeg)

Other screenshot

@landry, that’s great. Any chance to have the drawings already (I only need those flange sizes) ? I would like to start designing the housing for the grinder addon, specifically for v3.0, v3.1, v3.1-back-compat and v4.

thanks a lot

Cool, looks like this design made it already into the bazar. Is there any chance for Eindhoven outsiders to download and test this ?

Yes, it will be in the next download kit

The problem with having no voice people for people with production skills is that you again create designs and machines which are incompatible to each other; as result we – and PP – have again losses to suffer; it’s in the tens of thousands in case you don’t know.

For instance; if you release this design; all the mindless copy cats build this and sell it on the bazar and often we’d like to buy there just. We tried a few times to convince them to use our laser files but this turned often difficult since sellers can offer this only cheap when buying in bulk from laser services.

A way out would be if you finally add democratic tools to vote on designs instead of keeping your decisions arbitrary and communication one-way.

The longer you create fragmentation, the longer we have to wait for a serious product we can vouch for (certification, add-ons).

thanks in advance.

I guess it’s rather a no. no problem; As always, we’re happy to fix your designs at our expense and I guess v26 can finally enter the shop, in 2030 🙂

I just realized; this flange on the shredder like on the v4 is a nice idea but pretty much a problem; that would force people to use beams and these are hard to cut square (motor height alignment). I don’t expect people having machinist jacks. Beams is the last thing I’d take for mounting a shredder 🙂 The design before at least would enable stronger mounts more easy which don’t need to be precise as the beams. It’s easier to cut a solid bar and drill holes and that way you provide a way for alignment which is classy if folks can’t make it precise.

The other problem with this design is that there is open space to be filled between the 4 beam sockets. It’s not just for security but also avoiding a mess 🙂

Btw. the biggest hexbar i could find at our suppliers is 32mm;

In fact all our other frame designs become impossible with this flange; I know; I am just a forum guy with not enough points or patreon contributions but any chance you fix this design ?


thanks for sharing,

– blades : if you guys would at least read sometimes the forum; it’s all there since long 🙂
– the frame is btw. hard to ship and also nothing i’d base a flexible design on; extrusions combos were the best sellers we had. Besides, I guess you know the share between DIYers and folks who buy in the bazar; there are worlds in between 🙂

and …