Insect Class Motors
Size and weight are always considerations when selecting motors, and it is especially true with insect class robots. Also as with all robot combats think about the nature of your motors. Are they simply meant to deliver the weapon to the opponent or are they an integral part in your attack strategy. Take a look at the available kits to get an idea on how things are typically done. Wedge bots often have four independent motors, while drum bots save weight by having two drive motors.
22mm motors are common in 3lb robots with two being enough to drive a weaponed bot and four working well for a wedge or pushy bot. Brushed versions of 22mm motors are available from placeslike botkits.com but more advanced builders will convert them to brushless setups. This gives them more power for less weight than the brushed versions.
How to make brushless 22mm planetary gear motors
Although some motor resellers provide CAD files for their motors, over at GrabCAD a builder created a useful grouping of common motors.
The table below lists common motor sizes and some current examples (as of 2026). Specifications vary between gear ratios and versions, so check the seller's page. For choosing motors and gearing, see Drive Systems; for where to buy, see Suppliers.
| Name | Diameter | Length | Weight | Shaft | Voltage | RPM | Comments |
|---|---|---|---|---|---|---|---|
| N20 | 12mm | 10g | 3mm | 3v, 6v, 12v versions | Variable | Common in 150g bots | |
| 16mm | 16mm | 40.3mm | 28g | 3mm | 6v | Variable | Common in 1lb bots |
| 22mm | 22mm | 47.5mm | 73g | 4mm | 12v | 780 | Common in 3lb bots |
| KitBots Beetle Motor | 24.8mm | 49.3mm | 85g | 4mm | 12v | 930 | |
| FingerTech Mini Spark (N20) | 12mm | 3mm D | 7.4v rated | 728–1819 (by ratio) | Brushed N20 gearmotor for 150g bots; 20:1, 30:1 and 50:1 ratios | ||
| Pololu Micro Metal Gearmotors | 12mm | 3mm D | 6v and 12v versions | Variable | Huge range of ratios (5:1 to 1000:1) and power levels | ||
| FingerTech Silver Spark | 16mm | Variable | 16mm spur gearmotor for 1lb bots, many ratios; long shaft allows an outboard bearing | ||||
| Repeat Mini Brushed Mk2 | 16mm | 12v | 1220 | 16mm planetary, 22.6:1; for 1lb bots | |||
| FingerTech 22mm Planetary | 22mm | 85g | 12v | 730 | Brushed, 16.4:1; for 3lb bots | ||
| Repeat Compact Brushed | 22mm | 12v | 1070 | Brushed, 22.6:1; for 3lb bots | |||
| Repeat Compact 1806 Mk2 | 3S | about 1130 | Brushless (2300kv) with 22.6:1 gearbox; for 3lb bots | ||||
| FingerTech Brushless Mega Spark | 24mm gearbox | 6mm | Variable | Brushless 1806 motor (750, 1500 or 2300kv) with 27:1 planetary gearbox; for 3lb bots | |||
| Just Cuz Blitz Lite | Brushless 1604 gearmotor, 29:1; for 1lb and 3lb bots |
Protecting motors
Small gearmotors are often the first thing to fail in a match. Support their output shafts with a bearing where you can, mount them firmly (not with glue or zip ties), and threadlock their screws. See Hardening Motors and Drive Systems.