Two stage planetary gearbox 33:1

This is a 2-stage planetary gearbox, easy to 3D print and assemble. It provides a reduction ratio of about 33:1, making it great for hobby robotics, small mechanisms or as a demo model.

I’ve also included detailed step-by-step assembly instructions with pictures, so putting it together is straightforward.

Bill of Materials (BOM):

• Bearing: 6001(12x28x8)
• Fasteners: M3x10 bolts and nuts
• Motor: 12 V DC (8.5–15 V range), ~6900 rpm, Ø24.2 × 30.5 mm, 2 mm shaft
• Dowel pins: Ø3 × 10–11 mm

Tip: You can buy Ø3 × 10 mm steel dowel pins online, or make your own from 3 mm wood nails (cut to length). Be careful: if longer than 11 mm they will rub the housing, if shorter than 10 mm they won’t hold properly.

Print Instructions:

• Print all parts with 100% infill for maximum strength.
• The gearbox housing is designed for embedded M3 nuts: your printer will pause automatically so you can insert the nuts before resuming the print.
• Recommended material:  ABS,ASA… (PLA can wear faster under load).