Having the information shown on the display of a digital multimeter also recorded off-screen can be incredibly useful, but unless the device exposes something like SCPI on a network interface, you will have to get creative. In the case of the budget ANENG AN870 digital multimeter (DMM), [Bits und Bolts] really wanted to show its display clearly as an overlay in OBS instead of just the camera view, but with said DMM not offering an easy way he had to resort to just copying the data sent to its multiplexed LCD.

The GitHub project page contains the background information, as well as the instructions if you too have this DMM. It might of course also be useful as the jumping off point for your own DMM modification. In total the project requires three modules: an RP2040 Zero and HC-12 433 MHz transceiver on the DMM side, and another HC-12 plus ESP32-C3 module on the receiving side. A boost module is also added to generate 3.3 V out of the 2.4 V – 3 V provided by the meter’s two AA cells.

To be able to read the LCD signal lines, a custom PCB was created that is installed inside the DMM. With the LCD’s segments mapped, this meant being able to send a perfect copy of the display’s state to the ESP32-C3 and from there making it available via WiFi.

Cutting foam with a hot wire is a common technique to shape foam in a wide variety of shapes. If you want to cut something detailed and precise, like an airfoil, you probably want to use a computer-controlled cutting tool. Here [Michael Rechtin] has been working on creating a very versatile DIY CNC hot wire cutter, with the results recently announced in a video, along with the GitHub project repository if you want to give it a shake yourself.

Key in hot wire foam cutting is getting the nickel-chromium wire hot enough to gently slice through the foam rather than annihilating it or having the wire encounter significant resistance. For an automated cutter it either needs to be able to adjust the current on the fly, or have a predetermined optimal current for the cutting speed.

The machine itself is a 4-axis system, allowing the wire to be moved just about any way in between the two sides. It uses typical NEMA 17 stepper motors, along with other components that you’d find on a 3D printer. The same is true for the control board that processes the g-code from the software.

The unique part is the pulley-based mechanism that tensions the cutting wire, along with the way that the current gets passed through the wire, which uses MIG welding tips rather than just some alligator clips, which would probably also have worked but not looked as nice.

There are a few 3D-printed parts for which the STLs are provided, and the design is such that the entire assembly can be fairly easily collapsed into a compact shape that’s much easier to store if you’re not cutting foam every single day. For [Michael] cutting airfoils is the main use, for which you got a few software packages that are mentioned in the video.

You don’t normally think of die casting as something to do at home. Pressurized fluids demand respect at all times, which is perhaps in part why we see most projects skipping hydraulics for linear actuators. When the pressurized fluid is molten metal? Well, we’d say don’t try this at home, except that’s exactly what this video by [Know Art] is making us want to do. He’s doing die-cast aluminum, and it looks way easier than we thought it would.

If you’re wondering why anyone would attempt such a thing, it’s for the same reason die-casting has been an industrial powerhouse for the last couple hundred years — you can crank out a lot of parts, very quickly, with excellent detail and dimensional stability. You just need a mold, which in this process is called a die, and a way to squeeze metal into it with some force.

In this case the die was carved on a desktop CNC machine. Depending on how long you want your die to last, you’ll need something hard and heat resistant, like the graphite used in this video. Graphite is also used in constructing the piston for the injector, which is made from a modified hydraulic cylinder and a couple of old trampoline springs.

He first tests the setup with molten wax before moving onto aluminum, as the process is the same regardless: pour the hot liquid in, release the springs to provide the pressure that forces it into the die, and a part is made. It looks easy, if a bit frantic, as you have to work fast before the metal cools in the cylinder.

After CNC milling, EDM machining and all the fun things we’ve learned how to do with lasers and 3D printers, and now this we’ve got to wonder– is there any industrial process you can’t hack onto your desktop? We’ve even seen the chemists get in on the game.

Thanks to [Keith Olson] for the tip!

Nobody wants to breathe solder fumes; that’s a given. For most of us, an industrial-looking fan-and-filter made in China and picked up cheap feels like more than enough to keep our lungs clear. Other people, people like [George Conneely], have more refined tastes. Why have a fume extractor when you can have a work of art?

This is one of those projects where the images really speak for themselves, because the whole point is to be beautiful. Sure, the wooden case is lovingly sculpted by a—wait, it’s 3D-printed!? Yes, with the right stain and care applying it, it seems Wood PLA can fool the eye, or at least the camera. Inside that PLA case there’s a custom PCB with an ATMega microcontroller and some MOSFETS to drive the Nixie tubes. The two digits represent the fan’s set RPM as a percentage of maximum, as is clearly labeled. Using a READY/NOT READY indicator pulled from a Panvia Tornado to show whether the fan has actually spun up to its set speed is an amazing touch.

The only problem with this build is that it is too nice. We’d almost rather see it on Don Draper’s desk than risk dirtying it on a lab bench. Evidently, [George] ascribes to the philosophy that one should surround oneself with beauty whenever possible. Your tastes may differ, but to many, nixie tubes certainly qualify– whether on a desk clock or in a car’s dashboard, there’s just something about that incandescent glow.

Thanks to [George] for the tip.

Every experienced machinist knows the value of taking regular measurements. If one works carefully and checks dimensions frequently, it’s possible to make a part much more precise than could be made by relying on the machine’s accuracy alone. In a similar vein, it’s possible to make a measuring device out of comparatively crude parts, as long as their behavior is well understood. Related to both principles is [BubsBuilds]’s displacement sensor, which uses a 3D printed frame but reaches precision better than two micrometers.

Admittedly the printed parts aren’t the source of the sensor’s precision, that comes from an opto-interrupter. This design has a central stylus, one end of which contacts the object under measurement. The other end flattens to a knife-edge blade, which fits between the diodes of the opto-interrupter. As the stylus point is pressed in, the blade blocks off more light from reaching the photodiode, creating an output signal proportional to displacement. To keep the stylus from twisting or moving side-to-side, two flat, circular flexures hold the stylus in the center of a cylindrical housing.

[Bubs] printed several flexure variations to see how well they resisted and permitted various torques and forces, and a symmetrical flexure design proved best for his purposes. Once the sensor was assembled, he tested it against the measurements recorded by a laser confocal displacement sensor. This design was an update from a previous version, and it improved in a few regards: the non-linearity had decreased, and the repeatability was now better than two microns, though the range had been halved. Significantly, though, it’s now much easier to mount, making this an actually practical tool.

If, however, this doesn’t fit your needs, there are many other ways to build a linear displacement sensor, ranging from capacitive to magnetostrictive. On the manual side of things, we’ve also covered a comparison of calipers.