Several shelf boxes of various widths are held together by brightly-colored plus-sign-shaped connectors.

3D Printed Shelf Connector

Sometimes, you really need a custom shelf. Whether you have a weird-shaped space, weird-shaped stuff, or just want something different, making your own shelving can make your place more like home. The Plus Shelf by [shurly] aims to make building your own shelves a little easier with a 3D printed bracket.

These connectors aren’t just sitting flush against the wood of the shelf. Each end of the + sign actually sits in a 3/8″ drilled recess, giving a more secure fit. The pieces were printed on an Objet and then dyed in various bright shades to really make the shelving pop. The cubbies were assembled with biscuits after cutting down a sheet of plywood to the appropriate sizes. The 45˚ angles around the edges of the cubbies make the whole shelf system that much nicer.

The final shelf has a little wobble, but that’s probably because dying the shelf connectors made them “bendy.” Because of the instability with the friction fit, the shelf connectors were super glued into the shelf boxes. [shurly] hopes that a metal version of the connectors might be able to eliminate these problems in the future.

This shelving system not your cup of tea? Maybe you’d prefer this Vintage Adjustable Shelving Method or this MP3 Player Shelf.

When Only A TO92 Will Do

As through-hole components are supplanted by their surface-mount equivalents, we’re beginning to see the departure of once-common component form factors. Many such as the metal can transistors became rare years ago, while others still hang on albeit in fewer and fewer places. One of these is the once-ubiquitous TO92 moulded plastic transistor, which we don’t see very much of at all in 2022. [Sam Ettinger] is a fan of the D-shaped plastic blobs, and has gone as far as to recreate them for a new generation to enjoy.

Though a TO92 was a relatively miniature package in its day, it’s still large enough to easily fit a SOT23 or similar SMD packaged device on a small PCB. So the tiny board with just enough space for the part and the three wires was fabricated, ready for encapsulating. Epoxy moulding a TO92 gave very poor results, so instead an SLA print of a T092 shell was made. It fits neatly over the PCB, producing a perfect TO92 package. We’re sure a translucent pink package would have raised a few eyebrows back in the 1960s though.

There will come a time when restorers of old electronics will use and refine this technique to replace dead components. We’ve seen the technique before, after all.

Scripting Coils For PCB Motors

PCB inductors are a subject that has appeared here at Hackaday many times, perhaps most notably in the electromagnetic exploits of [Carl Bugeja]. But there is still much to be learned in the creation of the inductors themselves, and [atomic14] has recently been investigating their automatic creation through scripting.

A simple spiral trace is easy enough to create, but when for example creating a circular array of coils for an electric motor there’s a need for more complex shapes. Drawing a trapezoidal spiral is a surprisingly difficult task for a script, and we’re treated to a variety of algorithms in the path to achieving a usable design.

Having perfected the algorithm, how to bring it into KiCAD?  The PCB CAD package has its own Python environment built-in, but it’s not the most flexible in which to develop. The solution is to write a simple JSON interpreter in KiCAD, and leave the spiral generation to an external script that passes a JSON. This also leaves the possibility of using the same code in other PCB packages.

You can watch the whole video below the break. Meanwhile for more PCB electromagnetics, watch [Carl Bugeja]’s 2019 Supercon interview.

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3D Printed Sorter Separates Spare Hex Nuts With A Shake

Got a pile of mixed hex nuts? Sort them in no time by printing [jonafriendj]’s nut sorter, which has options for pretty much any nut size you’d be after (it’s labeled metric, but actually includes Imperial sizes as well.)

Something to admire about the design is the handy little raised labels on each of the sieves, and the fact that all the parts print entirely without supports. Designing a part to play to a manufacturing method’s strengths (and avoid its weaknesses) is good DFM, or Design for Manufacturing.

With 3D printing being the boon that it is to workshops and hobbyists everywhere, it certainly pays to strive for good DFM, especially for designs meant to be shared with others. Sometimes good DFM takes a page from other manufacturing methods like injection molding, and we end up with things like using crush ribs on printed parts.

Want to see a demonstration of [jonafriendj]’s nut sorting design? Check out the short video embedded below the page break. If that leaves you wanting, take a look at a motorized, automated DIY solution.

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A tiny CRT showing an eye, inside a plexiglass enclosure

This Eye Is Watching You From Its Tiny CRT

The days of cathode ray tubes, or CRTs, are firmly behind us, and that’s generally a good thing. Display tubes were heavy, bulky and fragile, and needed complicated high-voltage electronics in order to work. But not all of them were actually large: miniature display tubes were also produced, for things like camcorder viewfinders, and [Tavis] from Sideburn Studios decided to turn one of those into a slightly creepy art project.

The heart of this build is a one-inch CRT that was salvaged from an RCA video camera. [Tavis] mounted the tiny tube inside an acrylic box on a 3D printed base. Inside that base sits a Raspberry Pi along with a high-voltage driver and a power management board. The Pi continuously plays a video that shows a human eye blinking and looking in various directions. Just an eye, floating in space, looking at the world around it.

The magic is briefly lost when the Pi starts up, because it then shows a microscopic version of the Pi’s standard bootup sequence, but once the thing is running it adds a weird vibe to a room. It actually looks like something you’d find in an avant-garde art exhibition — in the video (embedded below) it’s accompanied by eerie music that gives it an even more unsettling feel. Electronic eyes are always a bit scary, especially when they’re actually looking at you.

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Magnetic Gearbox Design Improvements Are Toothless But Still Cool

Any project that contains something called a “flux modulator” instantly commands our attention. And while we’re pretty sure that [Retsetman] didn’t invent it after hitting his head on the toilet, this magnetic gearbox is still really cool.

Where most gearboxes have, you know, gears, a magnetic gearbox works by coupling input and output shafts not with meshing teeth but via magnetic attraction. [Retsetman]’s version has three circular elements nested together on a common axis, and while not exactly a planetary gear in the traditional sense, he still uses planetary terminology to explain how it works. The inner sun gear is a rotor with four pairs of bar magnets on its outer circumference. An outer ring gear has ten pairs of magnets, making the ratio of “teeth” between the two gears 10:2. Between these two elements is the aforementioned flux modulator, roughly equivalent to the planet gears of a traditional gearbox, with twelve grub screws around its circumference. The screws serve to conduct magnetic flux between the magnets, dragging the rotating elements along for the ride.

This gearbox appears to be a refinement on [Retsetman]’s earlier design, and while he provides no build files that we can find, it shouldn’t be too hard to roll your own designs for the printed parts.

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I’ll See Your Seven-Segment Mechanical Display And Raise You To 16 Segments

Mechanical multi-segment displays have become quite a thing lately, and we couldn’t be more pleased about it. The degree of mechanical ingenuity needed to make these things not only work but look good while doing it never ceases to amaze us, especially as the number of segments increases. So we submit this over-the-top 16-segment mechanical display (Nitter) for your approval.

The original tweet by [Kango Suzuki] doesn’t have a lot of detail, especially if you can’t read Japanese, but we did a little digging and found the video shown below. It shows a lot more detail on how this mechanism works, as well as some of the challenges that cropped up while developing it. Everything is 3D printed, and flipping the state of each of the 16 segments is accomplished with a rack-and-pinion mechanism, with the pinions printed right into each two-sided cylindrical segment. The racks are connected to pushrods that hit a punch card inserted into a slot in the rear of the display. The card has holes corresponding to the pattern to be displayed; when it’s pushed home, the card activates a mechanism that slides all the racks that line up with holes and flips their segments.

This isn’t the first multi-segment mechanical masterpiece from [Kango Suzuki] that we’ve featured, of course. This wooden seven-segment display works with cams rather than punch cards, but you can clearly see the hoe the earlier mechanism developed into the current work. Both are great, and we’re looking forward to the next segment count escalation in the mechanical display wars.

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