Reduction Gearbox (262,144:1 Gear Ratio)

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This reduction gearbox is a great way to demonstrate to students how gear ratios compound (it's also just fun to have as a desk toy).

Each compound gear has a 32-tooth and 8-tooth gear stacked resulting in a 4:1 gear ratio. With 9 gears in sequence, the total gear ratio is 262,144:1 and would require around 1,145,320 N to turn the final gear in 1 full rotation.

The design has a crank at both ends of the gearbox, one at the ‘light end’ (spin 262,144 times for a single rotation on the other end) and one at the ‘heavy end’ (you cannot move it).

The design should either screw or snap together easily, if they do not then scale the female parts up by 1% and that should fix the issue.

If you want to remove gears from the gearbox to reduce the ratio, you can replace them with one shim per removed gear and keep the teeth snugly fit.

Steps to assemble:

1. Put the front driving gear and handle on the frame

2. Put both bolts in their holes

3. Starting with the right bolt, slide the gears onto the bolts. Alternate each side and ensure the teeth are meshed

4. Once all gears are on the bolts, screw the nut onto the back (not too tight as it will jam the gears)

5. Optional; attach rear driving gear

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Update (29/12/2024):

The handle for both the front and rear driving gear was too short and conflicted with the axle bolt on both ends. A new handle has been uploaded that is longer and will not interfer. The 3MF print file has also been updated accordingly.

Thanks to @Tosa1234 for spotting the issue and providing the updated handle (https://makerworld.com/en/@tosa1234).