Apr 5, 2016 | By Alec

With our desktop 3D printers running for hours, getting the electrical bill is always a bit of tense moment. But even here, a 3D printing solution might be just what you need. Kansas City-based 3D printing guru Michael Curry (who sometimes goes by the name Skimbal) has built and 3D printed a wind turbine that generates some electrical power from Missouri’s endless winds, and this could be just what we need to counter the complaints from our significant others.

Michael Curry is quite a significant name in 3D printing, as a former 3DP Evangelist at MakerBot who frequently shares very innovative designs online. Remember this 70 lbs. 3D printed RC car? He is also a member of Kansas City’s Hammerspace, where he built a 3D printed wind turbine a few years ago. Called the Whirligig, it has been happily spinning in the wind for about two years now. “The Whirligig is a basic Axial Wind Turbine design. Its printed scoop segments spin on a shaft which is just six foot long piece of gas pipe. A ¾ inch delrin sphere at the top of the turbine acts as head bearing and two large metal bearings between the segments keep them spinning parallel to the shaft. Splined couplers tie the spinning parts together and allow limited flex and movement between the segments,” he says of the design.

However, Curry finally decided it was time for an upgrade with a generator – to make the Whirligig contribute a bit as well. Incidentally, the PLA parts on the Whirlygig showed no degradation at all after all those years, despite all the wind, snow, rain and sunshine that has been attacking it. “The ABS parts where another story. Both brackets were badly sun faded and had begun to lose their layer to layer adhesion. I could practically pull them apart in my hands,” he says. Time for an upgrade indeed.

To capture that wind energy, Curry was actually looking at two different capturing methods, wanting to try 3D printing the parts for a DIY alternator as well as reusing some old stepper as a generator. “Which method will work better? A DIY built Alternator, or a repurposed Stepper Motor from a 3D Printer?” he wonders. “Being an overachieving DIY Maker guy, naturally my first thought was to dive in and build my own 3D Printed three phase alternator. With information gleaned from DIY wind turbine websites, I set out on a quest of electromechanical discovery.”

The alternator he built used 9 coils of 22 gauge copper wire, wound around 3D printed cores and stored in a supporting disk. Each coil is of course connected to in an alternating set of three to create phase. “In theory, when the wind spins the turbine blades, the magnet will spin above over the coils. The alternating magnets will pass alternating negative and positive magnetic fields over the coils, exciting the electrons.  The electron's movement is rectified in to DC power by the two bridge rectifiers,” he says. While it looked good and should have done well in theory, the results were very different. Despite a good wind blowing, the alternator only generates 196.9 Microvolts. “Yeah, My alternator doesn't work very well,” he concludes.

That’s why it’s always good to have an alternative at hand, and when you’ve built a few 3D printers you can easily find one in NEMA 17 stepper motors. “I've heard Stepper motors can make great little generators,” Curry says. “We set up a quick bench test. An Adafruit NEMA 17, 2 bridge rectifiers, a multimeter, capacitor, lightbulb, and power drill. The theory is, we’ll spin the NEMA 17 with the power drill, which will produce an alternating voltage in each of the two coils. The rectifiers will convert the voltage to DC, charging the capacitor and lighting the light bulb. The capacitor smooths out the incoming voltage, so the multimeter can get a more stable reading of the voltage being produced.”

Fortunately, this worked a lot better. The initial results already generated up to 60 volts, so Michael began work on designing a generator with the stepper. “I settled on a somewhat Rube Goldberg solution. A spinning rain hood/internal gear that is spun by the turbine on a bearing ring of ½ inch delrin spheres. Inside the rain hood, a toothed internal gear meshies with a drive gear on pressed onto the stepper motor,” he explains on his blog. “As the turbine spins the rain hood, the gearing will spin the spin the stepper with about a 4:1 speed advantage. The delrin bearings keep everything spinning freely while keeping the teeth of the gears engaged with each other.”

Taking it for a test on a relatively quiet day, Curry was able to get 9 volts out of just a light breeze. Imagine what that could do in a proper Missouri storm. He is currently thinking about how to follow up on this project, and let’s hope is ambitious. How many 3D printed turbines would it take to power a makerspace?



Posted in 3D Printing Application



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Bryan Keil wrote at 4/11/2016 11:09:45 PM:

Why not just use a Model Airplane Electric Motor. Cheap and efficient.

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