An Early Attempt at a Magnet Motor

Here are some images of an attempt I made many years ago to make a permanent magnet motor. 

This device was designed around the alnico magnet assembly of an old loudspeaker. The general idea was that there would be attractive forces pulling together the two salient (toothed) rotors, in the 180 degree region in which they were completing the magnetic circuit; that they would be able to move apart again easily where there was much less magnetic flux between them (over the remaining 180 degrees); and that this would cause both rotors to turn.

Although the brass items, the turned steel items and the blanks for the rotors were of course made with a lathe, all of the rotor teeth were made by cutting with a jigsaw and a hand hacksaw, and finishing by filing. The cutting away of half the speaker steel assembly was also done with a hand hacksaw.

Years ago, I used to enjoy working in these "old school" ways. Nowadays I usually find them too tedious, time-consuming (especially when accuracy is required), and too much physical effort! I also grew tired of ending up with magnetised files, hacksaw blades etc. I now prefer, where possible, to use quicker and more efficient methods like laser-cutting, (although I don't have my own laser-cutter yet).

Nowadays I would always model a device like this first, using a magnetostatic simulation program capable of predicting the expected forces and torques, before I would ever consider building a physical prototype. Such a program would no doubt have told me what I found out from this prototype — it doesn't work!

Years later I did make a computer model of a development of this idea that did deliver a small amount of excess energy, and I'll discuss that in a future post.