3D printed stackable gearbox for brushless motor

Affordable brushless motors are great for a variety of motion applications, but often require a gearbox to control their speed. [Michael Rechtin] decided to try his hand at designing a stackable planetary gearbox for a brushless motor that allows him to add or remove stages to change the gear ratio.

The gearbox is designed around an inexpensive 5010 size, 360KV, sensorless motor from Amazon. Each stage consists of a set of 1:4 planetary gears which can be connected to another stage or to an output hub. This means that the output speed is reduced by a factor of four for each stage added. Thanks to the high pressure angle, the straight teeth and the fairly loose clearances, the gearbox is quite noisy.

To measure the torque, [Michael] mounted the motor-gearbox combo on a piece of aluminum extrusion and added a 100mm moment arm to apply force to a load cell. The first test actually broke the moment arm, so a reinforced version was designed and printed. The engine could exert around 9.5 Nm through the gearbox. This number may not be exact, as sensorless motors like this cannot provide a smooth output force at low speeds. As [Michael] suggests, adding a sensor and encoder would allow for better testing and lower speed applications. Find out in the video after the break.

We've already featured a number of [Michael's] projects, including a corn-hole board for bag tracking and a 3D-printed linear actuator.