vacuum

130 Articles

A Robotic Stylist For Your Lockdown Lengthened Locks

July 14, 2020 by 19 Comments

It’s perhaps easy to think that despite the rapid acceleration of technology that there are certain jobs that will never be automated out of existence. Generally the job said to be robot-proof is the one held by the person making the proclamation, we notice. But certainly the job of cutting and styling people’s hair could never be done by a robot, right?

We wouldn’t bet the farm on it, although judging by [Shane Wighton]’s quarantine haircut robot, it’ll be a while before the stylists of the world will be on the dole. Said to have sprung from the need to trim his boyishly long hair, the contraption is an object lesson recreating the subtle manual skills a stylist brings to every head they work on — there’s a reason it takes 1,500 hours or more of training to get a license, after all. [Shane] discovered this early, and realized that exactly replicating the manual dexterity of human hands was a non-starter. His cutting head uses a vacuum to stand the hair upright, 3D-printed fingers to grip a small bundle of hair, and servo-driven scissors to cut it to length. The angle of attack of the scissors can be adjusted through multiple axes, and the entire thing rotates on a hell-no-I’m-not-putting-my-head-in-that-thing mechanism.

To his great credit, [Shane] braved the machine as customer zero, after only a few non-conclusive life-safety tests with a dummy head and wig. We won’t spoil the ending, but suffice it to say that the thing actually worked with no bloodshed and only minimal damage to [Shane]’s style. The long-suffering [Mrs. Wighton], however, was not convinced to take a test drive.

In all seriousness, kudos to [Shane] for attacking such a complex problem. We love what he’s doing with his builds, like his basketball catcher and his robo-golf club, and we’re looking forward to more.

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An Affordable Home Made Vacuum Chamber

June 29, 2020 by 31 Comments

The term “vacuum” means many different things depending whether you are working on space equipment, scientific instruments, or even internal combustion engines. In our sphere it is so often used as a means to draw bubbles out of resin castings, for which it is a relatively easily achievable partial vacuum. It’s something [Fab] is using, in a vacuum chamber made from Plexiglass.

A simple Plexiglass box would collapse under the air pressure on its own, so to mitigate that it’s made from a piece of tube, and with an internal frame of aluminium extrusion with 3D printed joints to strengthen it from the inside. A pressure sensor allows regulation of the pump that drives the vacuum, and connections are made to the chamber using pneumatic hose connectors. It’s not immediately clear how it is sealed, whether there are nay gaskets or other sealant, or whether air pressure pushing the parts together provides enough of a seal.

We’ve featured a lot of vacuum chambers made for this purpose over the years, and we’d be interested to know what vacuum pump is being used here. If  you’re curious too and want to build your own, perhaps you could try a fridge compressor.

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Arm

Variable Mirror Changes Shape Under Pressure

June 27, 2020 by 10 Comments

Unless you’re in a carnival funhouse, mirrors are generally dead flat and kind of boring. Throw in some curves and things get interesting, especially when you can control the curve with a touch of your finger, as with this variable surface convex mirror.

The video below starts off with a long but useful review of conic constants and how planes transecting a cone can create circles, parabolas, or ellipses depending on the plane’s angle. As [Huygens Optics] explains, mirrors ground to each of these shapes have different properties, which makes it hard to build telescopes that work at astronomical and terrestrial distances. To make a mirror that works over a wide range of distances, [Huygens Optics] built a mirror from two pieces of glass bonded together to form a space between the front and rear surface. The front surface, ground to a spherical profile, can be deformed slightly by evacuating the plenum between the two surfaces with a syringe. Atmospheric pressure bends the thinner front surface slightly, changing the shape of the mirror.

[Huygens Optics] also built an interferometer to compare the variable mirror to a known spherical reference. The data from the interferometer was fed to a visualization package that produced maps of the surface shape, which you can easily see changing as the pressure inside the mirror changes. Alas, a deeper dive into the data showed the mirror to be less than perfect, but it’s fascinating to think that a mirror can flex enough to change from elliptical to almost parabolic with nothing more than a puff of air.

We’ve seen a couple of interesting efforts from [Huygens Optics] before, including this next-level spirit level. He’s not all about grinding glass, though — witness this investigation into discriminating metal detectors.

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Robot Arm Sucks In A Good Way

April 14, 2020 by 5 Comments

Building a robot arm is fun, but no longer the challenge it once was. You can find lots of plans and kits, and driving the motors is a solved problem. However, there is always one decision you have to make that can be a challenge: what effector to put on the end of it. If you are [MertArduino] the answer is to put suction at the end. If you need to grab the right things, this could be just the ticket for reliably lifting and letting go. You can see a video of the arm in action, below.

The arm itself is steel with four servo motors and comes in a kit. The video shows the arm making a sandwich under manual control. We suspect he might have put it under Arduino control but there’s no sudo for making sandwiches.

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[Ben Krasnow]’s Take On DIY Air Bearings

December 28, 2019 by 6 Comments

We’ve got to admit that watching [Ben Krasnow]’s new video on air bearings is tough. We found our eyes constantly checking the spherical air bearing in the foreground, which for the first eight minutes of the video just kept going. It was strangely hypnotic, and made it hard to concentrate on all the other cool stuff [Ben] was up to.

If the topic of air bearings seems familiar, it might be because we recently reported on DIY air bearings made from used EDM electrodes. [Ben] saw that too, and dusted off his old air bearing project. Literally, as it turns out, because the graphite blocks whose porosity and softness make them the perfect material for air bearings also makes for a dusty workshop. We’d recommend breathing protection of some sort while machining graphite. In addition to simple puck bearings, [Ben] came up with more complicated designs, including the aforementioned spherical bearing. He used the steel ball itself as a precision tool to grind the graphite out, first by coating it with abrasive and then by cutting grooves in it to act like a file. A cylindrical bearing was also cut, this time with sandpaper glued directly to the ground steel rod that would seat in the bearing.

[Ben]’s other innovation is vacuum preloading, where he applies both vacuum and pressure to the bearing plenum. The vacuum provides the force needed to capture the moving element while the pressure bears the load. It’s a careful balancing act, but it works well enough to capture the large steel ball and keep it turning effortlessly.

We really liked [Ben]’s take on air bearings, especially his thoughts on creating fully enclosed cylindrical bearings. Those could be useful for low-friction linear drives, and we look forward to seeing more on those.

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[Ben Krasnow] Builds A Mass Spectrometer

December 4, 2019 by 31 Comments

One of the features that made Scientific American magazine great was a column called “The Amateur Scientist.” Every month, readers were treated to experiments that could be done at home, or some scientific apparatus that could be built on the cheap. Luckily, [Ben Krasnow]’s fans remember the series and urged him to tackle a build from it: a DIY mass spectrometer. (Video, embedded below the break.)

[Ben] just released the video below showing early experiments with a copper tube contraption that was five months in the making; it turns out that analytical particle physics isn’t as easy as it sounds. The idea behind mas spectrometry is to ionize a sample, accelerate the ions as they pass through a magnetic field, and measure the deflection of the particles as a function of their mass-to-charge ratio. But as [Ben] discovered, the details of turning a simple principle into a working instrument are extremely non-trivial.

His rig uses filaments extracted from carefully crushed incandescent lamps to ionize samples of potassium iodide chloride; applied to the filament and dried, the salt solution is ionized when the filament is heated. The stream of ions is accelerated by a high-voltage field and streamed through a narrow slit formed by two razor blades. A detector sits orthogonal to the emitter across a powerful magnetic field, with a high-gain trans-impedance amplifier connected. With old analog meters and big variacs, the whole thing has a great mad scientist vibe to it that reminds us a bit of his one-component interferometer setup.

[Ben]’s data from the potassium sample agreed with expected results, and the instrument is almost sensitive enough to discern the difference between two different isotopes of potassium. He promises upgrades to the mass spec in the future, including perhaps laser ionization of the samples. We’re looking forward to that.

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Syringes Become Rockets In This Flying Build

October 30, 2019 by 3 Comments

Syringes have all kinds of useful applications in the workshop, from injecting fluids to helping pick up tiny components. There’s always room for a bit of levity however, and [Tom Stanton] decided to have a play with some syringe rocket builds.

The basic idea involves blocking the end of a syringe, and then pull the plunger to create a vacuum in the tube. When released, the plunger will rush forward from the atmospheric pressure counteracting the vacuum, hitting the end of the tube and launching the syringe forward.

[Tom]’s initial attempts with small syringes were fun, but larger builds struggled with breakages, sealing issues, and excessive weight. Some more luck was had with a vacuum cannon build, which was able to launch a projectile to a decent height, albeit without a lot of stability. [Tom] wrapped things up by designing a small 3D printed launcher that fits 10mm syringes and lets you shoot them around the workshop with abandon.

It’s fun to see the concept explored in detail, with [Tom] doing a great job of explaining the basic physics behind the phenomenon. If you’re hungry for more, consider using syringes as basic hydraulic actuators for model builds. Video after the break.

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