2202 Brushless Hubmotor for Antweight Combat Robots

Since Hubmotors are very usefull for combat robots, but only existed for 450g weightclasses and up, I created one that can be built from a 2202 brushless motor and only weighs around 35g (including mounting screws). You can get it down to 26g by using plastic bearings like these from igus, but i have not yet tested how well they hold up in fights...

Width: 16mm

Outside diameter: 44mm

Parts:

• 1x 2202 brushless motor, disassembled. Only the stator with coils, and the magnet ring will be used. The magnet ring needs to be cut/sanded/turned down to 4mm height.

• 2x 61704 bearings (20x27x4mm), or 2x lightweight 6704 plastic bearings

• 3x M3x3 brass inserts

• 1x M4x12 countersunk flathead screw

• 1x each printed part

Print the parts from something strong, like PA-CF or PC-CF, with 3 or more walls and at least 30% gyroid infill.

To mount the motor you need 6 M3 screws(example 1, example 2), do not insert them deeper than 4.5mm into the motor, or you might damage the coils!

To mount a weapon disk to the motor you will need 3 M3x8 socket head cap screws. Weapon disk thickness is recommended to be 3mm, but anything between 2-4mm should fit (use M3x6 screws for 2mm disks). An example weapon disk is included, this would weigh around 30g when made from toolsteel.

Assembly:

1. Use thread cutter to clean up the M3 and M4 threads if they didn't print cleanly.

2. Melt M3x3 brass inserts into Rotor 1 printed part.

3. Press bearing on Hub printed part.

4. Press Rotor 1 on bearing on Hub.

5. Press coil on Hub, with wires facing up.

6. Press magnet ring into Rotor 1.

7. Insert bearing into Rotor 2 printed part.

8. Press Rotor 2 on magnet ring.

9. Insert Hub Cap printed part into bearing in Rotor 2. Make sure to guide wires neatly through the hole.

10. Insert M4x12 screw to hold motor together.