Monday, September 16, 2013

Hand Cranked Generator

I have had several people ask about building a generator students can turn by hand. I am putting a short explanation and several pictures on my blog. We built one using an ECM motor minus the module.

It puts out 3 phase AC. It is regulated only by the speed of the person turning it: you would not want to run your computer on it. To get enough speed we used a 12 inch pulley for the students to turn and a 1 inch pulley on the motor shaft: This produces 12 spins of the generator for every one revolution of the hand crank. I ordered the bearings, pulleys, belt, and shaft from Grainger.

We used heavy slotted shelving material to make the frame. This also came from Grainger - but it was left over from other projects.

We brazed a large hex nut onto a hub that mounts on the shaft and we turn it with a large socket on the end of a speed wrench.
 It has been working for years - just needs a little tightening and adjusting from time to time. Students can fairly easily get to 120 volts - until I turn on a light.


One change I would make - we mounted the bearings to a couple of pieces of slotted angle and it is too flexible - hard to align the bearings so they don't bind. Plus, the bolts holding the slotted metal are also the ones that have to be loosened and tightened to adjust the belt. I would replace that with a solid block of metal and then mount that block to the frame.

 It took 2 of us about 4 hours to make.

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