halbach

5 Articles

Using The Wind And Magnets To Make Heat

June 25, 2024 by 53 Comments

On the face of it, harnessing wind power to heat your house seems easy. In fact some of you might be doing it already, assuming you’ve got a wind farm somewhere on your local grid and you have an electric heat pump or — shudder — resistive heaters. But what if you want to skip the middleman and draw heat directly from the wind? In that case, wind-powered induction heating might be just what you need.

Granted, [Tim] from the Way Out West Blog is a long way from heating his home with a windmill. Last we checked, he didn’t even have a windmill built yet; this project is still very much in the experimental phase. But it pays to think ahead, and with goals of simplicity and affordability in mind, [Tim] built a prototype mechanical induction heater. His design is conceptually similar to an induction cooktop, where alternating magnetic fields create eddy currents that heat metal cookware. But rather than using alternating currents through large inductors, [Tim] put 40 neodymium magnets with alternating polarity around the circumference of a large MDF disk. When driven by a drill press via some of the sketchiest pullies we’ve seen, the magnets create a rapidly flipping magnetic field. To test this setup, [Tim] used a scrap of copper pipe with a bit of water inside. Holding it over the magnets as they whiz by rapidly heats the water; when driven at 1,000 rpm, the water boiled in about 90 seconds. Check it out in the video below.

It’s a proof of concept only, of course, but this experiment shows that a spinning disc of magnets can create heat directly. Optimizing this should prove interesting. One thing we’d suggest is switching from a disc to a cylinder with magnets placed in a Halbach array to direct as much of the magnetic field into the interior as possible, with coils of copper tubing placed there.
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Can You 3D-Print A Stator For A Brushless DC Motor?

December 18, 2018 by 33 Comments

Betteridge’s Law holds that any headline that ends in a question mark can be answered with a “No.” We’re not sure that [Mr. Betteridge] was exactly correct, though, since 3D-printed stators can work successfully for BLDC motors, for certain values of success.

It’s not that [GreatScott!] isn’t aware that 3D-printed motors are a thing; after all, the video below mentions the giant Halbach array motor we featured some time ago. But part of advancing the state of the art is to replicate someone else’s results, so that’s essentially what [Scott!] attempted to do here. It also builds on his recent experiments with rewinding commercial BLDCs to turn them into generators. His first step is to recreate the stator of his motor as a printable part. It’s easy enough to recreate the stator’s shape, and even to print it using Proto-pasta iron-infused PLA filament. But that doesn’t come close to replicating the magnetic properties of a proper stator laminated from stamped iron pieces. Motors using the printed stators worked, but they were very low torque, refusing to turn with even minimal loading. There were thermal issues, too, which might have been mitigated by a fan.

So not a stunning success, but still an interesting experiment. And seeing the layers in the printed stators gives us an idea: perhaps a dual-extruder printer could alternate between plain PLA and the magnetic stuff, in an attempt to replicate the laminations of a standard stator. This might help limit eddy currents and manage heating a bit better. Continue reading “Can You 3D-Print A Stator For A Brushless DC Motor?” →

Step The Halbach From My Magnets

May 4, 2018 by 5 Comments

[Klaus Halbach] gets his name attached to these clever arrangements of permanent magnets but the effect was discovered by [John C. Mallinson]. Mallinson array sounds good too, but what’s in a name? A Halbach array consists of permanent magnets with their poles rotated relative to each other. Depending on how they’re rotated, you can create some useful patterns in the overall magnetic field.

Over at the K&J Magnetics blog, they dig into the effects and power of these arrays in the linear form and the circular form. The Halbach effect may not be a common topic over dinner, but the arrays are appearing in some of the best tech including maglev trains, hoverboards (that don’t ride on rubber wheels), and the particle accelerators they were designed for.

Once aligned, these arrays sculpt a magnetic field. The field can be one-sided, neutralized at one point, and metal filings are used to demonstrate the shape of these fields in a quick video. In the video after the break, a powerful magnetic field is built but when a rare earth magnet is placed in the center, rather than blasting into one of the nearby magnets, it wobbles lazily.

Be careful when working with powerful magnets, they can pinch and crush, but go ahead and build your own levitating flyer or if you came for hoverboards, check out this hoverboard built with gardening tools.

 

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3D-Printed Halbach Motor Part Two: Tuning, Testing

June 30, 2017 by 8 Comments

Building your own Halbach-effect brushless DC motor is one thing. Making sure it won’t blow up in your face another matter, and watching how [Christoph Laimer] puts his motor to the test is instructive.

You’ll remember [Christoph]’s giant 3D-printed BLDC motor from a recent post where he gave the motor a quick test spin. That the motor held together under load despite not being balanced is a testament to the quality of his design and the quality of the prints. But not wishing to tempt fate, and having made a few design changes, [Christoph] wisely chose to perform a static balancing of the rotor. He also made some basic but careful measurements of the motor’s parameters, including the velocity constant (Kv) using an electric drill, voltmeter, and tachometer, and the torque using a 3D-printed lever arm and a kitchen scale. All his numbers led him to an overall efficiency of 80%, which is impressive.

[Christoph] is shipping his tested BLDC off to the folks at FliteTest, where he hopes they put it to good use. They probably will — although they might ask for three more for a helicarrier.

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Powerful, Professional Brushless Motor From 3D-Printed Parts

May 8, 2017 by 23 Comments

Not satisfied with the specs of off-the-shelf brushless DC motors? Looking to up the difficulty level on your next quadcopter build? Or perhaps you just define “DIY” as rigorously as possible? If any of those are true, you might want to check out this hand-wound, 3D-printed brushless DC motor.

There might be another reason behind [Christoph Laimer]’s build — moar power! The BLDC he created looks more like a ceiling fan motor than something you’d see on a quad, and clocks in at a respectable 600 watts and 80% efficiency. The motor uses 3D-printed parts for the rotor, stator, and stator mount. The rotor is printed from PETG, while the stator uses magnetic PLA to increase the flux and handle the heat better. Neodymium magnets are slipped into slots in the rotor in a Halbach arrangement to increase the magnetic field inside the rotor. Balancing the weights and strengths of the magnets and winding the stator seem like tedious jobs, but [Cristoph] provides detailed instructions that should see you through these processes. The videos below shows an impressive test of the motor. Even limited to 8,000 rpm from its theoretical 15k max, it’s a bit scary.

Looking for a more educational that practical BLDC build? Try one cobbled from PVC pipes, or even this see-through scrap-bin BLDC.

Continue reading “Powerful, Professional Brushless Motor From 3D-Printed Parts” →