Summary

A 3/11 or 11/3 gear box made as a toy. Can be used as a demonstration example or a weekend project.

Instructions

This is a toy gear set built as an experiment/ prototype.

I made mine from 6mm MDF (I know, its a pattern with my designs). I actually deviated from the design shown by using 2x 6mm washers either side of the frame spacers rather than using 3x spacers.

You can follow the assembly to see what you'll need in terms of parts and quantity.

24.01.13 Update

For those who are looking to build this, youâ€™ll need

1x Planet_Spider_1
16x Spacer_6mm
1x Spacer_3_6mm
2x Frame_1
1x Internal spur gear_MOD 3-5 42t 20deg
3x Gear_MOD 3-5_12t_20deg
1x Gear_MOD 3-5_18t_20deg
1x Planet_Spider_3
2x Drive Boss 18mm dia dowel (length to suit)
3x 12dia x 20v lg dowels

You'll also need:
4x M6x45 hex head bolts (or equiv.)
Superglue
8x M6 washers (if you want to cheat like I did)
1x M6 Penny Washer (for a thrust washer- use anything that is to hand)

Build as follows:

Assemble the input shaft (18 tooth gear, Drive boss and Spacer_3_6mm). I added a thrust washer to the face of the gear in the form of a penny washer.
Connect the other drive boss to Planet_Spider_1. Add 3 no. 12dia x 20 lg dowels to the spider, add the three 12 tooth gears and cap off using the Planet_Spider_3. Make sure the gears spin.
1. Build the frame up by stacking Frame_1 â€“ Spacer (x2, or 2x 6mm washers and 1x spacer) â€“ Internal Spur Gear â€“ Spacer (x2, or 2x 6mm washers and 1x spacer). Donâ€™t add the other frame yet.
Insert one shaft assembly into the frame. Add the other shaft into the assembly.
Finally, add the other frame and fit the bolts. These shouldnâ€™t need nuts (mine didnâ€™t as the wood was a tight fit).

Iâ€™ve included the source files to allow you scale to suit. The module for the gears used is 3.5.

If I've missed anything, let me know.

That's it. Enjoy.

UPDATE - Photos of my build added

Another planetary gear box