Building Large Drone Motors From Scratch

Over the past decade or so, drones have gone from rather exotic flying machines, used and built by a select few, to something that many people use for a wide range of purposes. Still, some are more dedicated than others to this pursuit, including YouTuber Building with Logan. He especially enjoys flying five-inch FPV freestyle drones, but decided that he wanted to also get into the comparatively gigantic one-meter class.

Rather than simply buying four brushless motors and strapping them onto a frame with batteries and control hardware, he instead decided to built the motors themselves from scratch. His initial motor design uses a 15-coil, 20-magnet configuration, giving a three-to-four coil-to-magnet ratio, which appears to have stayed the same during the build process. However, many parts of the design, as outlined in the build video, were revised during development.

The first prototype, with coils wrapped around a 3D-printed core, is seen at the 4:00 mark. It spins way too fast, with too low of a torque output to be used in a one-meter drone with large propellers. The solution was to replace the 3D-printed core with a set of ferrous plates, which again had to be wrapped with wire – and wrapped yet again after adding enamel-based paint to prevent shorts. An outer “back iron” shell was also added to further enhance magnetic performance, eventually producing six pounds, six ounces of force, exceeding Logan’s project goals.

Logan also designed a hub and propeller assembly, and was eventually able to produce four of these motors for future droning. Now the only thing left to do is build and fly the one-meter drone itself!