Affordable brushless motors are suitable for a variety of sports applications, but usually require a gearbox to control its speed. [michaelrechtin] decided to try to design a stackable planetary gearbox for brushless motor, which allows him to add or remove stages to change the transmission ratio.
The gearbox is designed around a cheap, 5010 size, 360 kV, sensorless motor from Amazon. Each stage consists of a 1:4 planetary gear set, which can be connected to another stage or output hub. This means that the output speed decreases by four times for each additional stage. Due to the high pressure angle, straight cutting teeth and fairly loose clearance, the gearbox is very noisy.
To measure torque, [Michael] installed the motor gearbox combination on an aluminum extrusion and added a 100mm force arm to apply force to the load cell. The first test actually broke the torque arm, so an enhanced version was designed and printed. The motor can apply a force of about 9.5 nm through the gearbox. This figure may not be accurate because sensorless motors like this cannot provide smooth output at low speeds. As (Michael) said, adding sensors and encoders will allow better testing and low-speed applications. Check in the video after the break.
We have previously introduced many [michael] projects, including bag tracking corn perforated plates and 3D printing linear actuators.