Shred ring

UpdateThe specific grain mill I used for this was this one on Amazon; however, it seems these type of shredders get changed or updated all the time and the drum diameter can vary. If you do not see your drum's size, please message me with the dimensions of your shredder and I will do my best design a version of the model that fits your shredder.  A TPU gasket was also added and the tolerance of the fit was adjusted to fit more grain mills.

The Shred Ring

This printable ring add-on to a grain mill lets you shred material for longer and sift out particles that are already the correct size, all while the shredder is running! 

The threads on the output are designed to fit a standard US soda bottle thread. Additional updates will be made in the future to include other common bottle sizes if necessary.

 The grain mill

The specific grain mill I used for this was this one on Amazon; however, it seems these type of shredders get changed or updated all the time and the drum diameter can vary. If you do not see your drum's size, please message me with the dimensions of your shredder and I will do my best design a version of the model that fits your shredder.  A TPU gasket may make the seal a bit better I have included one in the files for the main ring. If you use it please let me know how well it works. 

Printing:

Print all parts in the same material you will be shredding. This is important because if little pieces break off of your shred ring while shredding you do not want different materials contaminating your regrind. ABS chips in a batch of PLA regrind is not fun TRUST ME I KNOW. It is unfortunate but it will set you up for the best possible success with your shredding and re-extrusion efforts. 

Print these parts with at least 6 walls : Main Shred Ring, Cyclone part A and Cyclone part B

Print the rest with at least 2 walls. 

.2 layer height. 

Supports are necessary for the main ring, and the vent plug, but not the outlet cover.

Hardware: (These applied to my grain mill but your results may vary)

2 X 100mm M6 bolts to replace the quick-release CAM bolts that the grain mill comes with.

2 X M6 spacers (or print included ones)

4 X M3x6mm bolts

4 X 4.5/5mm M3 heat set inserts

Assembly:

1. Insert heat set inserts into corresponding 4.2mm holes in the main ring part. 

2. Place chute cover part into main ring part and use M3 screws to fasten it together.

3. Place assembly onto grinder drum as shown in the photos.

4. Remove quick lock bolts from lid by unscrewing sheet metal cover, flanged nut and the nut inside the mount on the lid and replace these bolts with 100mm M6 bolts and reassemble cover.

5. Install lid on top of printed assembly on grain mill drum and lock down lid by turning the bolts until the flanged nuts tighten against the tabs on the grain mill drum as they would prior to modification.

 Using the Shredder: 

After placing the assembled shred ring on the grain mill, fill it with your scraps, purge poops, purge towers supports etc., screw on a bottle and secure the lid onto your mill. I run my mill for 1-2 minute intervals with about a 30 minute cooldown depending on how hot it gets in the chamber. You'll be surprised how quickly you can fill a 2L bottle even with such a long cooldown time. 

The vent hole is for adding forced air into the system. Or at least that is the idea... I haven't quite gotten it to work yet. 

If you are particularly impatient, a first stage shred through an electric wood chipper can reduce the size of larger parts and then use the grain mill as a second stage to further reduce the size of your shreds. THIS MAKES A LOT OF DUST, and it isn't recommended as you will inevitably end up breathing the stuff in unless you use proper PPE and figure something out to collect the dust throw into the air by the wood chipper.  

Thanks!

If you pick up this model, I just want to say thank you for helping fund my ability to keep making models like this!