The Mask Launcher; Like An Airbag For Your Face

One of the most effective ways to slow the spread of pathogens like the novel coronavirus is to have individuals wear facemasks that cover the nose and mouth. They’re cheap, and highly effective at trapping potentially infectious aerosols that spread disease. Unfortunately, wearing masks has become a contentious issue, with many choosing to go without. [Allen Pan] was frustrated by this, and set out to make a launcher to quite literally shoot masks directly onto faces.

To fire the masks, Allan built a pneumatic system that gets its power from a compact CO2 canister. This is hooked up to a solenoid, which is fired by the trigger. The high-pressure CO2 then goes through a split to four separate barrels cleverly made out of brake line ([Allen] says it’s faster to get parts from the automotive supply than the home store these days). Each barrel fires a bola weight attached to one of the strings of the mask, in much the same way a net launcher works. The mask is then flung towards the face of the target, and the weights wrap around the back of the neck, tangling and ideally sticking together thanks to neodymium magnets.

Amazingly, the mask worked first time, wrapping effectively around a dummy head and covering the nose and mouth. Follow-up shots were less successful, however, but that didn’t deter [Allen] from trying the device on himself at point-blank range. Despite the risk to teeth and flesh, the launcher again fires a successful shot.

While it’s obviously never meant to be used in the real world, the mask launcher was a fun way to experiment with pneumatics and a funny way to start the conversation about effective public health measures. We’ve featured similar projects before, too. Video after the break.

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Vintage Ammeter Becomes Plant Moisture Gauge

It’s not uncommon to happen across vintage measurement equipment at the local flea market or garage sale. Often with an irresistible aesthetic, and built to last decades, these tools nonetheless tend to be sidelined when modern multimeters are available. [Build Comics] had just such a piece on hand, and decided to repurpose it with some modern hardware instead.

The build begins with a Hartmann & Braun 60 amp ammeter. Replete in a nice wooden box, it’s the perfect candidate for a modern refit. The device uses an indicator of the moving iron type. Intending to turn the device into a soil moisture monitor, [Build Comics] began by removing the original heavy-wound coil. In its place, a custom coil was installed instead, wound on a 3D printed bobbin using a modified sewing machine. This allows the meter to be easily driven by an Arduino with little more than a transistor on a GPIO pin. To detect moisture, a Iduino ME110 moisture probe was used. Complete with cloth-covered wire to maintain the vintage look. The original meter plate was also photographed, modified, and reprinted, to read moisture levels instead of current.

If you’re interested in these gauge restoration techniques but don’t have a green thumb, no worries. [Build Comics] used similar tricks to put together a gorgeous weather station that would look great on your desk.

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Wireless Sax Mic Done On The Cheap

Sometimes, economies of scale don’t work in our favor. While guitarists and singers will find themselves well catered to by the accessories market, players of fancier, less popular instruments will often have to dig deeper in their pockets to get what they need. [Henry Goh] found himself in need of a saxophone mic. However, off-the-shelf solutions were a touch expensive, and thus he decided he could probably whip something up himself.  (Video, embedded below.)

Parts of a saxophone, for the uninitiated. The microphone should be placed a good distance from the center of the bell to pick up the best sound.

It’s a simple solution, one that we could imagine any maker quickly whipping up with junkbox parts. Not one to skimp on quality, [Henry] picked a Rode Wireless Go paired with a lavalier mic for a quality wireless microphone solution. The real problem would be mounting the device, intended to be worn on a shirt, to the right position in front of the saxophone’s bell.

To achieve this, most dedicated sax mics used a bendable arm to allow the position to be readily changed. Instead, [Henry] whipped up some mounts on the 3D printer that would allow him to mount the Rode wireless mic hardware on an bendy Energizer LED torch. The torch even comes with a clamp allowing it to be easily attached to the instrument, making fitment a cinch.

[Henry] estimates the solution saved him up to $800 SGD. The final result is cost effective, and gives quality easily good enough for amateur and community performances. As a bonus, the hack is non-destructive, meaning you can repurpose the lavalier mic for other work as needed.

We love a good hack on the cheap, and it’s something we see all the time in the music scene. This guitar build is a great example of the form.

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How To Choose The Right GPS Module For Your Project

You’ve built a brand new project, and it’s a wonderful little thing that’s out and about in the world. The only problem is, you need to know its location to a decent degree of accuracy. Thankfully, GPS is a thing! With an off-the-shelf module, it’s possible to get all the location data you could possibly need. But how do you go about it, and what parts are the right ones for your application? For the answers to these questions, read on! Continue reading “How To Choose The Right GPS Module For Your Project”

Tensile Testing Machine Takes 3D Printed Parts To The Breaking Point

If you’re serious about engineering the things you build, you need to know the limits of the materials you’re working with. One important way to characterize materials is to test the tensile strength — how much force it takes to pull a sample to the breaking point. Thankfully, with the right hardware, this is easy to measure and  [CrazyBlackStone] has built a rig to do just that.

Built on a frame of aluminium extrusion, a set of 3D printed parts to hold everything in place. To apply the load, a stepper motor is used to slowly turn a leadscrew, pulling on the article under test. Tensile forces are measured with a load cell hooked up to an Arduino, which reports the data back to a PC over its USB serial connection.

It’s a straightforward way to build your first tensile tester, and would be perfect for testing 3D printed parts for strength. The STEP files (13.4 MB direct download) for this project are available, but [CrazyBlackStone] recommends waiting for version two which will be published this fall on Thingiverse although we didn’t find a link to that user profile.

Now we’ll be able to measure tensile strength, but the stiffness of parts is also important. You might consider building a rig to test that as well. Video after the break.

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A High Torque Gearbox You Can Print At Home

Typically, when we think of 3D printed parts, we think of unique parts with complex geometries that would be hard to fabricate with other techniques. Strength is rarely the first thing that comes to mind, due to the limitations of thermoplastics and the problem of delamination between layers. However, with smart design, it’s possible to print parts capable of great feats, just as [Brian]’s high-torque gearbox demonstrates.

Pulling a car is a great way to show off the strength of your build.

The gearbox consists of entirely 3D-printed gears, along with the enclosure, with the only metal parts being a few bearings and shafts. Capable of being produced out of PLA on a regular FDM printer, [Brian] has successfully tested the gearbox up to 132 kg∗cm. The suspicion is that there may be more left in it, but some slippage was noticed in the gear train when trying to tow a Ford Focus with the handbrake still on.

Even better, with the addition of a potentiometer, the gearbox can be used as an incredibly tough servo. [Brian] demonstrates this by lifting 22 kg at a distance of 6 cm from the center of the output shaft. The servo does it with ease, though eventually falls off the bench due to not being held down properly.

It’s a build that shows it’s possible to use 3D-printed parts to do some decently heavy work in the real world, as long as you design appropriately. [Brian] does a great job of explaining what’s involved, discussing gear profile selection and other design choices that affect the final performance. We’ve seen similar work from others before, too. Video after the break.

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Head-Tracking NES Water Blaster Is Good Summer Fun

Super Soakers were great fun back in the day, but adults tend to get tired of the manual labour of pumping pretty quickly. [Sean] decided to build something a touch more modern, coming up with this head-tracking water blaster.

The water spray tracks the movement of the wearer’s head. With a camera mounted on the nozzle, this allows the user to simply look to designate targets. Similar technology is used in military fighter jets.

To eliminate pumping, the build instead enlists the services of an electric pump, powered by a 12 V battery. Pushing water through a tube into a 3D printed nozzle, it provides a fat stream of water with around 5 meters range, with little effort from the user. The nozzle is fitted into a NES Zapper, and attached to a servo pan-tilt platform. The camera is mounted on the water gun, and hooked up to a set of Fat Shark FPV goggles with an IMU unit. When the user looks around, the water gun moves in sync with their head movements. This allows for the user to look at targets to hit them with the water stream, a very intuitive method of aiming.

It’s a fun build that’s perfect for the summer, and an easy one to recreate for anyone with some spare servos and FPV gear. Of course, with a little face-tracking software, it would be easy to hit targets automatically. Video after the break.

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