The Internal Workings of Electric Motors: Episode 1


(Taco Wako Mako) #1

There are a variety of different types of electric motors; However, in this article we’re only going to discuss the two simple rotary types of motors. Those being the AC electric motor and the DC electric motor. The difference between the two being the type of magnet in the outer shell of the motor. In an AC motor the outer, non-rotating magnet is an electromagnet. In a DC motor however, the outer magnet is a so called permanent magnet” which is called this because peoples’ life spans aren’t long enough to realize that it loses its magnetic abilities quite rapidly in the grand scheme of things.

Sorry, tangent over. Let’s start with a DC motor since it’s simpler (in my opinion) to grasp, conceptually. A basic DC motor basically works by having two coils internally (which are connected in series, often times more than two coils for smoother rotation especially with bigger motors) which are connected to plates on opposite sides of the shaft of the motor, curved to match the shaft’s curvature with a small gap between them on both sides of the shaft. This will be clearly visible in the images provided in subsequent episodes.

Then, in cheaper motors springy thin metal pins (the type I’ll be using) or in more expensive motors, a carbon bar with a spring behind it pushing it into the plate on the shaft, precisely positioned to fire the connections in time. I won’t have that luxury since I’m making mine all from scrap. These components are known as “brushes” and I’ll be making mine with some kind of scrap steel and using the same or similar for the contacts on the shaft itself.

Here’s a (somewhat hastily made) animation of the brushes contacting, well, the contacts…

The shaft will be a short segment of steel bar that used to be the axle of a remote control car. I’m unsure as to how I’m going to attach the coil mount at this moment, though I’m sure I’ll come up with something soon…I’m thinking zip ties would probably work pretty well. Use an X shape over the crossing bars and cinch them down really tight. This is the initial plan that I intend to try, however the backup plan for its inability to not slide back and forth will be putting some epoxy on and around the joint, making a T shape. Not sure what I’m going to do if that goes to shit. I’ll figure something out.

In the meantime I need to find a way to mount everything. I’m going to use bearings for both ends of the shaft, manufacture the contacts on the shaft and the brushes, wrap the coils using wire from a microwave transformer, probably use wood for the bearing mounts…that might be the easy way to go since I have access to a scroll saw and drill press + lots of hand drills, and find some suitable permanent magnets.

Until then, toodles and happy crafting if you’re building along.

taco signing off o/


Welcome to the forums, dude. Just a suggestion, maybe including some sort of visual aid would help people understand the bigger picture.

(Taco Wako Mako) #3

Visual aids are on the way, I just have to get them modeled, animated, and rendered.

EDIT: it’s mostly modeled, mostly shaded, needs some animation work, and needs all the rendering.

(system) #4

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