Nathan Matthews, by day a web developer in California, has designed and built Delta Tower, Core XY, and Cartesian style 3D printers. While he says he’s currently working on a 2.8W, 245nm laser cutter and etcher, it’s his 3D printed brushless pulse motor that caught our attention.
He says he’s always wanted to build a motor, but it took until recently for him to acquire the tools and skills to make it happen with CAD and 3D printing.
Magnets are often placed on the rotating portion of home-built motors, and while brushless motors are typically 85-90% efficient, DC brush motors are only around 75-80% efficient. The difference in efficiency generally comesdown to the total power used by the motor being turned into rotational force, and thereby, less energy is lost as heat.
Brushless DC electric motors are also often referred to as “electronically commutated motors.” They are synchronous motors powered by a DC electric source via an integrated inverter or switching power supply which produces an AC electric signal which in turn drives the motor.
The rotor part of a brushless motor is often what’s known as a permanent magnet synchronous motor, and they may be described as stepper motors, but stepper motor designs tend to be used for operations where they are frequently stopped with the rotor in a defined angular position.
“I got inspired after watching LaserSaber’s EZ spin motor videos thinking I could definitely do that,” he writes. “Turns out there aren’t official specs or build instructions. He has a few videos that, if you’re careful, you can use to catch the necessary details.”
Matthews design features five arms for the rotor with two magnets to each arm. All the magnets face ‘North,’ or outward. Ten coils alternate between ‘push’ and ‘pull’ mechanic, and he says the setup gave him “decent” results from a single AA battery.
The designer drew up the frame for his motor in SketchUp, and then 3D printed it in PLA using his own custom, CoreXY machine. He says the motor parts were printed with very sparse infill, and while he hasn’t yet posted his .stl files as he’s still considering changing the design for a next iteration, he does plan to share them at some point.
According to Matthews, it took him “a few hours” to wind up all the coils by hand – each one took approximately 300 turns – and they were all wound with a similar technique.
“It wasn’t so bad. The most annoying thing was trying to keep count and someone would call or break my concentration,” Matthews says. “I ended up weighing each one but I should have checked the resistance instead. I won’t lie: my brain drifted into dreams of the apocalypse and having to do this to make a generator and survive. I know that’s an absolutely indulgent thought, but it was kinda fun.”
Will you take on the task of 3D printing a brushless pulse motor like this one by Nathan Matthews? Let us know in the 3D Printed Brushless Pulse Motor forum thread on 3DPB.com.