Turning A Single Bolt Into A Combination Lock

In our search for big-box convenience, we tend to forget that locksmiths once not only copied keys but also created complex locks and other intricate mechanisms from scratch. [my mechanics] hasn’t forgotten, and building a lock is his way of celebrating of the locksmith’s skill. Building a combination lock from a single stainless bolt is probably also showing off just a little, and we’re completely fine with that.

Granted, the bolt is a rather large one – an M20x70 – and a few other materials such as brass rod and spring wire were needed to complete the lock. But being able to look at a single bolt and slice it up into most of the stock needed for the lock is simply amazing. The head became the two endplates, while the shank was split in half lengthwise and crosswise after the threads were turned off; those pieces were later turned down into the tubes and pins needed to create the lock mechanism. The combination wheels probably could have come from another – or longer – bolt, but we like the look of the brass against the polished stainless, as well as the etched numbers and subtle knurling. The whole thing is a locksmithing tour de force, and the video below captures all of it without any fluff or nonsense.

If working in steel and brass isn’t your thing, fear not – a 3D-printed combination lock is probably within your reach. Or laser cut wood. Or even plain paper, if you’re not into the whole security thing.

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Torturing An Instrumented Dive Watch, For Science

The Internet is a wild and wooly place where people can spout off about anything with impunity. If you sound like you know what you’re talking about and throw around a few bits of the appropriate jargon, chances are good that somebody out there will believe whatever you’re selling.

Case in point: those that purport that watches rated for 300-meter dives will leak if you wiggle them around too much in the shower. Seems preposterous, but rather than just dismiss the claim, [Kristopher Marciniak] chose to disprove it with a tiny wireless pressure sensor stuffed into a dive watch case. The idea occurred to him when his gaze fell across an ESP-01 module next to a watch on his bench. Figuring the two needed to get together, he ordered a BMP280 pressure sensor board, tiny enough itself to fit anywhere. Teamed up with a small LiPo pack, everything was stuffed into an Invicta dive watch case. A little code was added to log the temperature and pressure and transmit the results over WiFi, and [Kristopher] was off to torture test his setup.

The first interesting result is how exquisitely sensitive the sensor is, and how much a small change in temperature can affect the pressure inside the case. The watch took a simulated dive to 70 meters in a pressure vessel, which only increased the internal pressure marginally, and took a skin-flaying shower with a 2300-PSI (16 MPa) pressure washer, also with minimal impact. The video below shows the results, but the take-home message is that a dive watch that leaks in the shower isn’t much of a dive watch.

Hats off to [Kristopher] for doing the work here. We always love citizen science efforts such as this, whether it’s hardware-free radio astronomy or sampling whale snot with a drone.

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Jigsaw Motor Uses PCB Coils For Radial Flux

Electric motors are easy to make; remember those experiments with wire-wrapped nails? But what’s easy to make is often hard to engineer, and making a motor that’s small, light, and powerful can be difficult. [Carl Bugeja] however is not one to back down from a challenge, and his tiny “jigsaw” PCB motor is the latest result of his motor-building experiments.

We’re used to seeing brushless PCB motors from [Carl], but mainly of the axial-flux variety, wherein the stator coils are arranged so their magnetic lines of force are parallel to the motor’s shaft – his tiny PCB motors are a great example of this geometry. While those can be completely printed, they’re far from optimal. So, [Carl] started looking at ways to make a radial-flux PCB motor. His design has six six-layer PCB coils soldered perpendicular to a hexagonal end plate. The end plate has traces to connect the coils in a star configuration, and together with a matching top plate, they provide support for tiny bearings. The rotor meanwhile is a 3D-printed cube with press-fit neodymium magnets. Check out the build in the video below.

Connected to an ESC, the motor works decently, but not spectacularly. [Carl] admits that more tweaking is in order, and we have little doubt he’ll keep optimizing the design. We like the look of this, and we’re keen to see it improved.

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Fourier Explained: [3Blue1Brown] Style!

If you ask most people to explain the Fourier series they will tell you how you can decompose any particular wave into a sum of sine waves. We’ve used that explanation before ourselves, and it is not incorrect. In fact, it is how Fourier first worked out his famous series. However, it is only part of the story and master video maker [3Blue1Brown] explains the story in his usual entertaining and informative way. You can see the video below.

Paradoxically, [3Blue1Brown] asserts that it is easier to understand the series by thinking of functions with complex number outputs producing rotating vectors in a two-dimensional space. If you watch the video, you’ll see it is an easier way to work it out and it also lets you draw very cool pictures.

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Paint The Rainbow With This Skittle-Dropping Pixel Art Robot

We hackers just can’t get enough of sorters for confections like Skittles and M&Ms, the latter clearly being the superior candy in terms of both sorting and snackability. Sorting isn’t just about taking a hopper of every color and making neat monochromatic piles, though. [JohnO3] noticed that all those colorful candies would make dandy pixel art, so he built a bot to build up images a Skittle at a time.

Dubbed the “Pixel8R” after the eight colors in a regulation bag of Skittles, the machine is a largish affair with hoppers for each color up top and a “canvas” below with Skittle-sized channels and a clear acrylic cover. The hoppers each have a rotating disc with a hole to meter a single Skittle at a time into a funnel which is connected to a tube that moves along the top of the canvas one column at a time. [JohnO3] has developed a software toolchain to go from image files to Skittles using GIMP and a Python script, and the image builds up a row at a time until 2,760 Skittle-pixels have been placed.

The downside: sorting the Skittles into the hoppers. [JohnO3] does this manually now, but we’d love to see a sorter like this one sitting up above the hoppers. Or, he could switch to M&Ms and order single color bags. But where’s the fun in that?

[via r/arduino]

A Guide To Shop Equipment Nobody Thinks About: Clean, Organized, And Efficient

When planning out a workspace at home, the job, or at a makerspace, we all tend to focus on the fun parts. Where the equipment will go, how you’ll power it, what kind of lights you’ll get, etc, etc. It’s easy to devote all your attention to these high-level concepts, which often means the little details end up getting addressed on the fly. If they get addressed at all.

But whether we want to admit it or not, an organized workspace tends to be more efficient. That’s why [Eric Weinhoffer] has put together a blog post that details all those mundane details that we tend to forget about. It’s not exactly exciting stuff, and contains precisely as much discussion about whiteboards as you probably expect. That said, it’s thorough and clearly comes from folks who’ve had more than a little experience with setting up an efficient shop.

So what’s the first thing most shops don’t have enough of? Labels. [Eric] says you should put labels onĀ everything, parts bins, tools, machines, if it’s something you need to keep track of, then stick a label on it. This does mean you’ll likely have to buy a label maker, but hey, at least that means a new gadget to play with.

Of course, those self-stick labels don’t work on everything. That’s why [Eric] always has a few rolls of masking tape (such as the blue 3M tape you might be using on your 3D printer bed) and some quality markers on hand to make arbitrary labels. Apparently there’s even such a thing as dry erase tape, which lets you throw an impromptu writing surface anywhere you want.

[Eric] also suggests investing in some collapsible cardboard bins which can be broken down and stored flat when not in use. If you’ve got the kind of situation where you’ll always have more or less the same amount of stuff then plastic is probably your best bet, but in a more dynamic environment, being able to collapse the bins when they aren’t in use is a capability we never even realized we needed until now.

As you might imagine, the post also touches on the issues of keeping sufficient safety gear available. We’ve talked about this in the past, but it’s one of those things that really can’t be said too many times. Having a wall of meticulously labeled storage bins is great, but it’s going to be the last thing on your mind if you manage to get an eye full of superglue.

Locking Up Lock Washers

We’ll admit most of us are more comfortable with solder and software than mechanical things. However, between robots, 3D printers, and various other mechanical devices, we sometimes have to dig into springs, belleville washers, and linear actuators. Unless you are a mechanical engineer, you might not realize there’s a lot of nuances to something even as simple as a nut and bolt. How many threads do you need to engage? Do lock washers work? [Engineer Dog] has a post that answers these and many other questions.

The top ten list starts off with something controversial: split ring lock washers don’t work. The original post cites a paper that claims they don’t except in very special circumstances. However, he updated the post later to say that some people disagree with his cited study. In the end, you’ll have to decide, but given there are other options, maybe we’ll start using those more often.

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