10/19/2025 - Planning the Dual Shaft Shredder

After doing some research, it seems that dual-shaft shredders will have an advantage over single-shaft shredders in the sense that dual-shaft shredders will give off smaller, more uniform shreds. However, the design of dual shaft shredders is more complex, since there are two shafts - twice as many moving parts (blades, washers, shafts), and the necesity to transmit the rotation using gears.
Some helpful sources mentioned how different gear ratios will enable better shearing, so I think I can make multiple gear configurations in CAD. (1:1 and 3:2 gear ratios)

11/3/2025 - Created First Base

So I do have some experience from the first shredder I made, so this went by a lot faster. The base is built to be extra chunky to take advantage of 3D printing. I plan to manufacture this shredder with m3 screws and nuts instead of m5, since I believe that more smaller fasteners can be stronger than fewer, larger fasteners.

11/6/2025 - More CAD Work - Blades + Shaft + Gears

Today, I did some more modeling work on the dual shaft shredder. I created custom shaft collars to secure the shafts, and I also created herringbone gears. I also made the framework for the blades.

11/9/2025 - Shredder Coming to Life

Did a lot of work in CAD, and the shredder seems to be getting closer and closer to the final goal! I decided to make the blades 5 toothed, a good balance of bite and grinding. I also modeled in the the hopper (safety first!). Lastly, I made the side wall blade cleaners. These should prevent the plastic from building up in between the blades.

11/22/2025 - Researched some shredder design tips

So in this work session,I did a lot more enrichment in the world of industrial shredders. It is quite interesting to see all the variations of shredders that have their own unique selling point. In the case of industrial shredders, high torque motors are used. But for my case, I will need to make design choices that minimize the torque requirements.

11/30/2025 - Added Labels to Design

So I fixed up the design here and there, and I added some built-in labels for easy assembly. This was pretty easy to do with Fusion's text tool. I think this is a vital update since without the labels, it would be super easy to mix up which parts go where.

12/1/2025 - Brainstorming to create a gearbox

I am working on starting a 3D printable gearbox for the shredder. In order to create a reduction, I will need a small gear driving a bigger gear. And if I repeat that, a gearbox will be made!

12/2/2025 - Working on Gearbox

So today I began working on the 3D printed gearbox. I think I'm going to use 608 bearings to reduce drag. This'll make the gearbox and gears quite chunky. My process for making gears is to generate them and then align them (stacked on top of each other), and then combine.

12/9/2025 - Polished up gearbox - added motor mount

Today, I finished up the gearbox by creating a mount for the motor and finishing the gearbox enclosure. I will be using a 2826 brushless DC motor to drive the gearbox.

1/1/2026 - Gearbox: added top mount and aesthetic effects

I managed to integrate the gearbox with the shredder with a 12mm ID bearing (since my shredder uses 12mm shafts). I 3D modeled a lid to keep everything in place, and I also created some vents for good airflow.

1/10/2026 - Assembly of Gearbox

I assembled the gearbox: I pressed in the 608 bearings (I had to use a hammer). Then, with the correct herringbone gear orientation, I assembled each of the gears. This took quite a while because of how tight the space is in the gearbox. If the gearbox cage was “open”, it would be a lot easier.

1/16/2026 - A better, easily mounted gearbox

So I noticed that the gearbox I had assembled is definitely aesthetically pleasing, but it is extremely hard to use/mount due to its curved shape and weird output shaft. So I spent a long time going back into the design and reverted some of the details. Now that I'm working with a rectangular shape, design changes and mounting will be a lot easier to implement!

1/17/2026 10 AM - More Work on New Gearbox

Spent some time doing more work on the new gearbox! Modified the design and added some new features. Pretty straightforward - mainly just got my ideas out of my brain and onto CAD.

1/17/2026 12 PM - Gearbox V3 work - but then Fusion decided to crash

So I made a lot more progress with the assembling of the gearbox (integration hell), and I guess the design wasn't super aesthetically pleasing. Then, Fusion decided to glitch out, and the file is corrupted, so I can't even open the gearbox model. Exporting the STEP doesn't work either... At least I have idea of what I'm doing, but I'm pretty mad that a lot of progress was wasted.

1/18/2026 - Build time!

Had a nice long work session building the gearbox and shredder. The shredder definitely works and is a huge improvement from my old design. I think I’m gonna make my gearbox bulkier with better mounting onto the shredder. Otherwise, it works well.

1/21/2026 - Creating Custom Bearings for Custom shaft profiles

So I kinda want to upgrade the shredder to use 2020 extrusions as shafts, so I spent some time creating custom bearings. These bearings use steel balls, and it took some trial and error to get it spinning just right.