Few hackers have trouble understanding basic electric motors. We’ve all taken apart something that has a permanent magnet DC motor in it and hooked up its two leads to a battery to make it spin. Reverse the polarity, reverse the spin; remove the power, stop the spin. Stepper motors (and their close cousins, brushless DC motors) are a little tougher to grok, though, especially for the beginner. But with a giant 3D printed stepper motor, [Proto G] has made getting your head around electronically commutated motors a little easier.
While we’ve seen 3D printed stepper motors before, the size and simple layout of this one really lends to understanding the theory. With a 3D-printed frame, coils wound on nails, and rare-earth magnets glued to a rotor, this is an approachable build that lays the internals of a stepper motor out for all to see and understand. You can easily watch how the rotor lines up as the various coils are energized in a circular pattern, although it might be more revealing to include bi-color LEDs to indicate which coils are energized and what the polarity is. Those would be especially helpful demonstrating the concept of half-stepping. We’d also like to see more detail on the controller electronics, although admittedly all the video-worthy action is in the motor itself.
[Proto G]’s project isn’t going to have you cranking out usable stepper motors from your 3D printer anytime soon. Indeed, with NEMA-17 motors going for $14USD on Adafruit, and plenty of surplus motors of all shapes and sizes available on the cheap, it won’t be cost effective to roll your own motors for quite a while. Then again, if we’re ever to release the full potential of additive manufacturing and start the decentralized industrial revolution, understanding how complex electromechanical devices like steppers work is going to be key to developing processes to manufacture them on demand.