Ways To Empirically Identify A Magnet’s Polarity

September 27, 2026 by Donald Papp 13 Comments

Every magnet has a north and a south pole, but which is which? Sometimes it matters. If a product one builds features a magnetic closure or other part, the polarity of those magnets should be consistent in assembly. So how does one ensure they never glue a magnet wrong again? [Clough42] shows several ways to identify a magnet’s north and south poles using things many of us probably have ready at hand, and goes into a bit of theory while he’s at it.

Probably the easiest way is to use a known-good and clearly labeled reference magnet. Same poles repel, and opposites attract. But if that’s not available, a simple magnetic compass can help. Because opposite poles attract, a compass’s north point will be attracted toward a magnet’s south pole, and vice versa.

A Hall effect sensor, or an electromagnet — the winding and current flow determine the polarity — are other ways to measure a magnet’s poles. And here’s where [Clough42] dives into some details of how magnetic fields actually act, because it explains some seemingly strange behavior.

For example, at around 4:08 he demonstrates a Hall effect sensor board that is documented as lighting an LED when the south pole of a magnet is held to its front. It does that, but it also lights the LED when the north end of the magnet is held to the sensor’s back. That’s because the sensor isn’t actually directly sensing the magnet’s pole, it’s sensing the orientation of a magnetic field. The lesson is clear: make sure you’re measuring what you think you’re measuring. Near the end of the video he demonstrates a similar experience with a handy mobile phone app that senses magnetic fields by reading the device’s internal magnetic compass; by waving a strong magnet around, the detected polarity flips back and forth even though the magnet’s orientation isn’t changed.

So what does one do after positively identifying a magnet’s north and south poles? Label it clearly for use as a known-good reference magnet in the future is our suggestion. Watch the whole video below, then take a few minutes to dive into the nitty-gritty of what magnets actually are and how they work.

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Enormous Fluid Simulation On Flip Dots Is Also Enormous Amount Of Work

September 27, 2026 by Donald Papp 5 Comments

Flip dot displays are cool, and more people realize that after [mitxela]’s fluid simulation on flip dots installation was on display at EMF 2026. As glorious as the result is, it was also an amazing amount of work!

Not only did [mitxela] need to source a large number of flip dots, he also needed to find a solution for driving them that didn’t end up more trouble than it was worth. Just about everything about the surplus flip dots — from electrical requirements to mounting — was a pain to work with in one way or another. Even his optimized method of integrating a custom backpack-style driver board into the existing PCB involved a staggering amount of soldering. This project was a long time coming, and the work never really let up.

The payoff, however, is exquisite. Check it out in the video (embedded below) which really shows it off. Flip dots are like nothing else, and the subtle rippling of sound that accompanies their physical movement is oddly soothing.

The installation at EMF 2026 had a GRAVITY CONTROL joystick that allowed folks to interactively shift the display, but [mitxela] also has an accelerometer mounted so that the display physically reacts to being moved. It’s a fantastic spectacle, even more impressive in light of the work it involved.

Unsure how, exactly, flip dots work? We’ve covered all the details about how these devices function. And while a large number would be prohibitively expensive for most projects, if your project can get away with only one dot you’re probably in luck.

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Easy Ways To Sink A Hardware Startup

September 26, 2026 by Donald Papp 16 Comments

[Ryan Walker] may have written up his observations a few years ago, but the lessons are just as relevant today as they were back then. He shares five easy ways to sink your hardware startup.

It’s a reminder that while hardware startups are unique, there are basic business realities that still apply because the hardware itself is going to be only one part of a whole. These business fundamentals can be a drag, but it’s worth giving them some attention. But if that’s not your jam, no worries. As [Ryan] experienced, they will explain themselves one way or another.

A good one is skipping market research. Do customers actually exist for this thing? Or forgoing market testing — do the customers actually want it enough to pay for it? One of the worst things to be stuck with is a product that everyone likes, but nobody wants to buy.

Premature optimization is another good one that a number of our readers can probably relate to in one way or another. It’s one thing to buy a tool or a part that one doesn’t end up needing, but when that gets scaled up it can put a real dent in a fledgling business’s development.

We’ve also shared insights on what it takes to develop a product and get it out there, whether as a solo entrepreneur or as part of a larger team, to help nudge the process toward success.

Robot Makes Literal Daisy Chains

September 24, 2026 by Donald Papp 3 Comments

[Jude Robinson]’s robot Daisy has an unusual function: making a literal chain of daisies. The device is his student final project and demonstrates how a system can replace sensing with clever mechanical constraints. Instead of bringing tools to bear on each daisy, the daisies are brought to the tools in a repeatable, deterministic way.

Daisy is essentially two X-Y gantries with grippers facing one another. Between them is a conveyor upon which daisies are fed, plus a blade at the top with a threading post nearby. A gripper takes a daisy, feeds the stem through the hole in the previous one, then lifts the new addition up to a scalpel blade which cuts a short incision. The thin threading post goes through the new hole in the new stem, ready for the next daisy to be inserted. The two gantries alternate roles, building the chain one daisy link at a time.

[Jude] says that daisy stem shape and diameter have the most impact on reliability, so it’s very important to constrain the daisies such that the scalpel and threading operations work reliably. This is primarily done with v-shaped profiles in the grippers which automatically center stems of different sizes. The sheath around the scalpel blade also plays a role in constraining and supporting the stems as they are gently pierced and sliced. Tuning these elements was a big part of making the system work.

Watch it in action in the video (embedded below) which shows how clever mechanical design can turn an uncertain problem — like how to handle daisies of different sizes — into a deterministic one with the help of clever mechanical design. That same concept is at work in everything from simple nut sorters to highly complex paper airplane machines.

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Tiny Scratch-Built Cyberdeck Is In Mint Condition

September 22, 2026 by Donald Papp 18 Comments

[Salim Benbouziyane] shows off his TN Deck, a tiny custom cyberdeck built into an Altoids tin. It’s a skillful build that really makes the most of the available space, and includes not only screen and keyboard but also rechargeable power supply and speaker.

The TN Deck is built around the Raspberry Pi Compute Module Zero, which is essentially the same as a Pi Zero W but in a more compact, castellated PCB form factor intended to be integrated into other designs. [Salim]’s custom PCB also handles power, sound, and puts a custom keyboard at the front running QMK, which is pretty much the best choice for custom keyboards and macropads of all kinds.

A D-pad and some gamepad buttons come in handy. The slot in the center is for the speaker.

The keyboard itself is mostly 3D printed. Each button consists of a dome tactile switch on the PCB, covered with a thin and flexible membrane printed in TPU and topped with 3D-printed keycaps. The markings are courtesy of [Salim]’s desktop IR laser marking machine, because a little trial-and-error with lasers can yield good marks on 3D prints. [Salim] says the keys don’t have much travel and the ergonomics aren’t the best, but what it lacks in comfort it makes up for in small size and economical design.

We also really liked [Salim]’s use of a printed drill guide for putting precise holes in the Altoid tin for things like an audio jack, taking the guesswork out of tool positioning.

Some cyberdecks are made to suit specific needs, and others are made for the love of the game. The TN Deck is one of the latter and [Salim]’s previous CM Deck was a bit of both. We can’t wait to see what he makes next.

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Full-Color Looks Great On 3D Printed Sliding Puzzles

September 16, 2026 by Donald Papp 4 Comments

[Angus] of [Maker’s Muse] shows off both a parametric, print-in-place sliding puzzle design he created, and the results of UV printing full-color designs on the same. The results look beautiful, and there was a whole lot of trial and error involved in the process.

The design includes a pop-out tile, which can be re-inserted to a finished puzzle.

Creating a good print-in-place sliding puzzle depends a lot on tolerances. Today’s 3D printers are much more capable in this regard than they were ten or so years ago, but getting the right feel to the pieces was still a long learning process. It’s not at all easy to get all the different characteristics in the right balance. On one hand, if the pieces are too tight they won’t slide easily. But if they are too loose, the puzzle can bind because the pieces have too much play. It may also flex enough to pop apart. And of course, the shape of the pieces and their mating surfaces are constrained to angles and shapes that 3D print reliably. [Angus] persevered and succeeded, and shows off everything from cute 3 x 3 units to a massive scaled-up 11 x 11 puzzle, printed on his Prusa XL.

Getting the color onto the print is the work of a desktop UV ink printer, the same model our own Tom Nardi had a hands-on look at last year. [Angus] shows how printing a single color image onto the puzzle is pretty easy and looks great, but what’s even better is a textured relief image with some real tactile depth to it. Expect a lot more work to do for that, because thick layers of ink gum the puzzle up with overspray unless one avoids printing over the gaps in the tiles.

Watch both the puzzles and the color printing in action in his video, embedded just below.

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Tips To Model Your Next CNC Cabinet In CAD Before Buying Anything

September 15, 2026 by Donald Papp 11 Comments

[Clough42] has started a new CNC control cabinet build, and uses it as an opportunity to demonstrate why he models the whole thing out in CAD before ordering parts or physically building anything. One may wonder why to bother, and the simple answer is to ensure there are no surprises or waste. [Clough42] has built plenty of these cabinets and there’s always something that isn’t as expected.

Modeling out an entire cabinet sounds like it should be easy, because today one can obtain 3D models for components from industrial suppliers with ease. In practice, it’s a process fraught with little gotchas.

For example, a STEP file of a component can lack convenient geometric snap points. An enclosure will be a single entity, without a separate door (and certainly not articulated at the hinge). [Clough42] shows ways to deal with all of these, and more, in Fusion 360. With a few simple techniques laying out an entire cabinet in CAD can be easy.

Planning before buying or building is a form of prototyping, and prototyping helps surface problems so they can be avoided before they become costly. This concept extents to design work as well; model everything out to avoid simple goofs like a screwdriver handle trapped by its surrounding bits.

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