2 Million to 1: Nested Strain Wave Gearbox

This is a functional, 100% human-engineered mechanical demonstration piece showcasing a massive 2,023,680:1 total reduction ratio through a custom nested strain wave drive system.

 

It is designed to be fully 3D printed with minimal hardware required, making it a highly accessible build that visually breaks down complex mechanical engineering. It includes a custom base to display the final assembly while it runs.

The Math (Gear Ratios)

The extreme reduction is achieved through four nested stages:

•    Stage 1: 40:42 (20:1)
•    Stage 2: 68:70 (34:1)
•    Stage 3: 96:98 (48:1)
•    Stage 4: 124:126 (62:1)

Bill of Materials (BOM)

•    All printed components (including display stand)
•    1x USB TT Motor
•    2x 2.5x6mm machine screws (Note: These are the exact same screws used in the Cyber Brick build)
•    Lubricant (for the flexsplines)

Assembly Instructions

1. Mount the Motor: Install the USB TT motor into the assembly and secure it with the motor housing using the two 2.5x6mm machine screws.
2. Install Wave Guides: Snap the wave guides (top gear portions) securely into their designated places.
3. Prep the Flexsplines: Apply lubricant to the smooth side of the flexsplines (the flexible rings).
4. Seat the Flexsplines: Carefully install the lubricated flexsplines into their appropriately sized channels.
5. Final Drive: Press the wave generator onto the TT Motor shaft.