Ways To Embed Magnets In 3D Prints And Not Ruin Printers

Adding magnets to a 3D print can be very useful in a design, but there are some things that can trip you up if you’re not aware of them. In a recent video by [Lost in Tech] some of the essentials are covered, including why you shouldn’t get magnets near most extruder nozzles or the printing bed.

The easiest method is of course to add magnets in after printing, using friction fit with or without ribs, or with a dab of glue. Here making sure that the magnet stays in place is the trick, as you do not want the magnet to get lost or end up in the tummy of a curious pet or toddler.

The magnetic pattern on an FDM printer's magnetic bed. (Credit: Lost in Tech, YouTube)
The magnetic pattern on an FDM printer’s magnetic bed.

Things get spicy when you’re talking about adding magnets during the printing process, as some extruders are made of a ferromagnetic material and thus a magnet will happily stick to said nozzle if it’s not pure brass or similar. As seen in the video even some purported ‘brass’ nozzles aren’t pure enough to not be significantly ferromagnetic.

Another issue is that of heat, which is something that magnets generally do not like much. Using magnets like you’d use heat inserts for bolts is a recipe for disaster, as the heat from a soldering iron will demagnetize the magnet, which for the typical magnet is less than 200°C. At least this should mean that the magnet stuck to your extruder nozzle will eventually fall off by itself after it demagnetizes.

With the bed of the typical FDM printer these days you’re talking about magnetically attached plates, with the underlying heated bed using a Halbach array configuration as is typical of flat magnets, yet with the gotcha that these aren’t typically real Halbach arrays, but knock-offs with simply alternating north-south pole magnets. As it turns out, these types of magnetic arrays can be disturbed by another magnet, such as a powerful neodymium magnet near said printing bed, flipping polarity in a way that cannot be easily undone.

You can still install magnets during printing, but it’s recommended to use something like side-insertion, where the extruder nozzle cannot pull out a magnet. Regardless of your approach, it’s good to know of the risks with ferromagnetic nozzles, the magnetic bed and treating magnets like they’re just heat inserts. While you can get higher-temperature magnets, many of the same issues still remain here.

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Magnetic-Suspension Hoverboard Is Only 11 Years Late

Anyone who saw Back to the Future II was disappointed when 2015 rolled around with nary a hoverboard in sight. There have been various attempts to fake it, but none of them quite have the feel of floating about wherever you’d like to go that the movie conveys. The little-known YouTuber [Colin Furze] has a new take on the idea: use magnets. Really big magnets.

If you’re one of [Colin]’s handful of subscribers, then you probably saw his magnetic-suspension bike. We passed on that one, but we couldn’t resist the urge to cover the hoverboard version, regardless of how popular [Colin] might be on YouTube. It’s actually stupidly simple: the suspension is provided by the repulsive force between alarmingly large neodymium magnets. In this case, two are on the base plate that holds the skateboard ‘trucks’, and two are on the wooden ‘deck’ that [Colin] rides upon.

Of course magnetic repulsion is a very unstable equilibrium, so [Colin] had to reduce the degrees of freedom. In his first test, that was with a pair of rods and linear bearings. That way the deck could only move in the z-axis, providing the sensation of hovering without allowing the deck to slide off its magnetic perch. Unfortunately those pins transferred too much vibration from the ground into the deck, ruining the illusion of floating on air.

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Finding A Way To Produce Powerful Motors Without Rare Earths

The electric vehicle revolution has created market forces to drive all sorts of innovations. Battery technology has progressed at a rapid pace, and engineers have developed ways to charge vehicles at ever more breakneck rates. Similarly, electric motors have become more powerful and more compact, delivering greater performance than ever before.

In the latter case, while modern EV motors are very capable things, they’re also reliant on materials that are increasingly hard to come by. Most specifically, it’s the rare earth materials that make their magnets so good. The vast majority of these minerals come from China, with trade woes and geopolitics making it difficult to get them at any sort of reasonable price. Thus has sprung up a new market force, pushing engineers to search for new ways to make their motors compact, efficient, and powerful.

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