Measurement Is Science

June 21, 2025 by Elliot Williams 22 Comments

I was watching Ben Krasnow making iron nitride permanent magnets and was struck by the fact that about half of the video was about making a magnetometer – a device for measuring and characterizing the magnet that he’d just made. This is really the difference between doing science and just messing around: if you want to test or improve on a procedure, you have to be able to measure how well it works.

When he puts his home-made magnet into the device, Ben finds out that he’s made a basically mediocre magnet, compared with samples out of his amply stocked magnet drawer. But that’s a great first data point, and more importantly, the magnetometer build gives him a way of gauging future improvements.

Of course there’s a time and a place for “good enough is good enough”, and you can easily spend more time building the measurement apparatus for a particular project than simply running the experiment, but that’s not science. Have you ever gone down the measurement rabbit hole, spending more time validating or characterizing the effect than you do on producing it in the first place?

Iron Nitride Permanent Magnets Made With DIY Ball Mill

June 19, 2025 by Maya Posch 10 Comments

Creating strong permanent magnets without using so-called rare earth elements is an ongoing topic of research. An interesting contestant here are iron nitride magnets (α”-Fe₁₆N₂), which have the potential to create permanents magnets on-par with with neodymium (Nd₂Fe₁₄B) magnets. The challenging aspect with Fe-N magnets is their manufacturing, with recently [Ben Krasnow] giving it a shot over at the [Applied Science] YouTube channel following the method in a 2016 scientific paper by [Yanfeng Jiang] et al. in Advanced Engineering Materials.

This approach uses a ball mill (like [Ben]’s planetary version) with ammonium nitrate (NH₄NO₃) as the nitrogen source along with iron. After many hours of milling a significant part of the material is expected to have taken on the α”-Fe₁₆N₂phase, after which shock compaction is applied to create a bulk magnet. After the ball mill grinding, [Ben] used a kiln at 200°C for a day to fix the desired phase. Instead of shock compaction, casting in epoxy was used as alternative.

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Diagram showing the structure of the base.

Magic On Your Desk Via MagLev Toy

May 7, 2025 by Tyler August 9 Comments

Magnets aren’t magic, but sometimes you can do things with them to fool the uninitiated — like levitating. [Jonathan Lock] does that with his new maglev desk toy, that looks like at least a level 2 enchantment.

This levitator is USB-powered, and typically draws 1 W to 3 W to levitate masses between 10 g and 500 g. The base can provide 3 V to 5 V inductive power to the levitator to the tune of 10 mA to 50 mA, which is enough for some interesting possibilities, starting with the lights and motors [Jonathan] has tried.

In construction it is much like the commercial units you’ve seen: four permanent magnets that repel another magnet in the levitator. Since such an arrangement is about as stable as balancing a basketball on a piece of spaghetti, the permanent magnets are wrapped in control coils that pull the levitator back to the center on a 1 kHz loop. This is accomplished by way of a hall sensor and an STM32 microcontroller running a PID loop. The custom PCB also has an onboard ESP32, but it’s used as a very overpowered USB/UART converter to talk to the STM32 for tuning in the current firmware.

If you think one of these would be nice to have on your desk, check it out on [Jonathan]’s GitLab. It’s all there, from a detailed build guide (with easy-to-follow animated GIF instructions) to CAD files and firmware. Kudos to [Jonathan] for the quality write-up; sometimes documenting is the hardest part of a project, and it’s worth acknowledging that as well as the technical aspects.

We’ve written about magnetic levitation before, but it doesn’t always go as well as this project. Other times, it very much does. There are also other ways to accomplish the same feat, some of which can lift quite a bit more.

DIY Linear Tubular Motor Does Precise Slides

March 31, 2025 by Donald Papp 25 Comments

We’ve seen plenty of motor projects, but [Jeremy]’s DIY Tubular Linear Motor is a really neat variety of stepper motor in a format we certainly don’t see every day. It started as a design experiment in making a DIY reduced noise, gearless actuator and you can see the result here.

Here’s how it works: the cylindrical section contains permanent magnets, and it slides back and forth through the center of a row of coils depending on how those coils are energized. In a way, it’s what one would get by unrolling a typical rotary stepper motor. The result is a gearless (and very quiet) linear actuator that controls like a stepper motor.

While a tubular linear motor is at its heart a pretty straightforward concept, [Jeremy] found very little information on how to actually go about making one from scratch. [Jeremy] acknowledges he’s no expert when it comes to motor design or assembly, but he didn’t let that stop him from iterating on the concept (which included figuring out optimal coil design and magnet spacing and orientation) until he was satisfied. We love to see this kind of learning process centered around exploring an idea.

We’ve seen DIY linear motors embedded in PCBs and even seen them pressed into service as model train tracks, but this is the first time we can recall seeing a tubular format.

Watch it in action in the short video embedded below, and dive into the project log that describes how it works for added detail.

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Two tools for placing magnets with ease, one for each polarity.

An Attractive Magnet Insertion Tool

September 1, 2024 by Kristina Panos 9 Comments

Magnets are pretty nice little tools. [EmGi] has used them in many a cool 3D printed build with great success. But getting them where you want can be really tricky. More often than not, you end up with glue all over your fingers, or the magnets fly out of place, or they stick together when you don’t want them to.

Well, [EmGi] created a mighty fine magnet insertion tool that you can print for yourself. It’s finger-operated and uses a single embedded magnet to place magnets wherever they’re needed.

This thing went through several designs before [EmGi] ever printed it out. Originally, there were two magnets, but there was an issue where if the tool wasn’t lifted off perfectly, it would send the magnet flying.

But now it works great, and [EmGi] even deposited an array of 64 magnets without using glue to test it out before printing a second one to handle the other polarity. Check out the build/demo video after the break.

While you’re printing and placing magnets, why not make yourself a couple of magnetic switches? You can even make ’em for keyboards.

Continue reading “An Attractive Magnet Insertion Tool” →

You Can 3D Print Yourself Some Simple Magnetic Switches

August 22, 2024 by Lewin Day 9 Comments

Permanent magnets aren’t typically switchable. They’re always doing their magnet thing. However, if you align them with a bunch of other magnets in just the right way, you can create a permanent magnet that you can effectively switch on and off. [Andrew Klein] has done just that with his 3D-printed magnetic switch design.

The concept is simple enough. The design consists of a 3D-printed housing in two parts, top and bottom. When set into one orientation, the housing holds two arrays of magnets in opposite orientations. This effectively cancels out their magnetic fields and allows you to move the assembly around as if it’s pretty much not magnetic at all. However, rotate the device to its alternative orientation, and the magnets poles are aligned. This effectively combines their magnetic fields and makes the assembly act as one big large magnet.

These devices are useful if you want to create magnetic clamps or fixtures that can be attached and detached at will from ferrous surfaces. Being able to effectively “switch the magnet off” is much easier than trying to wrench a powerful magnet from a metal plate, after all.

You can do something similar with electromagnetic techniques, too! Video after the break.

Continue reading “You Can 3D Print Yourself Some Simple Magnetic Switches” →

A 3D-printed magnetic fidget business card with ID storage.

2024 Business Card Challenge: Magnetic Fidget Card

July 7, 2024 by Kristina Panos 5 Comments

If you want someone to keep your business card around, you should probably make it really cool-looking, or have it do something useful. It’s kind of the whole point of the 2024 Business Card Challenge. And while we’d normally expect electronics of some persuasion to be involved, we must admit that this magnetic fidget card definitely does something, at least when manipulated. And even when it’s just sitting there, the card has a storage slot for IDs, or whatever you want.

Have you ever played with a magnetic fidget? They are quite satisfying, and making one yourself is likely to be even cheaper than making one of the spinning variety. This one uses a whopping 16 neodymium magnets, which means that it’s probably quite aurally satisfying as well as fun to handle.

And of course, since it’s 3D-printed, you can put whatever you want on the faces and update them easily if something changes. Bonus points to [Bhuvan Bagwe] for designing some for the Hackaday crew!