More often than you think, scientific progress starts with a simple statement: “Huh, that’s funny…” That’s the sign that someone has noticed something peculiar, and that’s the raw fuel of science because it often takes the scientist down interesting rabbit holes that sometimes lead to insights into the way the world works.
[Ben Krasnow] ended up falling down one of those rabbit holes recently with his experiments with magnets and flames. It started with his look at the Zeeman effect, which is the observation that magnetic fields can influence the spectral lines of light emitted by certain sources. In a previous video, [Ben] showed that light from a sodium lamp could be dimmed by a powerful electromagnet. Some of his viewers took exception to his setup, which used an oxy-acetylene flame doped with sodium passing through the poles of the magnet; they thought the effect observed was a simple magnetohydrodynamic effect, and not the Zeeman effect he was supposed to be testing. That led to the experiments in the video below, which started with a candle flame being strongly deflected by the magnet. [Ben] methodically worked through the problem, eliminating variables by going so far as to blow soap bubbles of various gasses within the magnet’s poles to rule out the diamagnetism of oxygen as a cause of the phenomenon. He finally showed that even hot air by itself is deflected, using a simple light bulb and a FLIR camera. It’s good stuff, and well worth a watch.
Invariably when we write about living on Mars, some ask why not go to the Moon instead? It’s much closer and has a generous selection of minerals. But its lack of an atmosphere adds to or exacerbates the problems we’d experience on Mars. Here, therefore, is a fun thought experiment about that age-old dream of living on the Moon.
Inhabiting Lava Tubes
The Moon has even less radiation protection than Mars, having practically no atmosphere. The lack of atmosphere also means that more micrometeorites make it to ground level. One way to handle these issues is to bury structures under meters of lunar regolith — loose soil. Another is to build the structures in lava tubes.
A lava tube is a tunnel created by lava. As the lava flows, the outer crust cools, forming a tube for more lava to flow through. After the lava has been exhausted, a tunnel is left behind. Visual evidence on the Moon can be a long bulge, sometimes punctuated by holes where the roof has collapsed, as is shown here of a lava tube northwest from Gruithuisen crater. If the tube is far enough underground, there may be no visible bulge, just a large circular hole in the ground. Some tubes are known to be more than 300 meters (980 feet) in diameter.
Lava tubes as much as 40 meters (130 feet) underground can also provide thermal stability with a temperature of around -20°C (-4°F). Having this stable, relatively warm temperature makes building structures and equipment easier. A single lunar day is on average 29.5 Earth days long, meaning that we’ll get around 2 weeks with sunlight followed by 2 weeks without. During those times the average temperatures on the surface at the equator range from 106°C (224°F) to -183°C (-298°F), which makes it difficult to find materials to withstand that range for those lengths of time.
It sounds like an overly complicated method a supervillain would use to slowly and painfully eliminate enemies — a chamber with variable oxygen concentration. This automated environmental chamber isn’t for torturing suave MI6 agents, though; rather, it enables cancer research more-or-less on the cheap.
Tasked with building something to let his lab simulate the variable oxygen microenvironments found in some kinds of tumors, [RyanM415] first chose a standard lab incubator as a chamber to mix room air with bottled nitrogen. With a requirement to quickly vary the oxygen concentration from the normal 21% down to zero, he found that the large incubator took far too long to equilibrate, and so he switched to a small acrylic box. Equipped with a mixing fan, the smaller chamber quickly adjusts to setpoints, with an oxygen sensor providing feedback and controlling the gas valves via a pair of Arduinos. It’s quite a contraption, with floating ball flowmeters and stepper-actuated variable gas valves, but the results are impressive. If it weren’t for the $2000 oxygen sensor, [RyanM145] would have brought the whole project in for $500, but at least the lab can use the sensor elsewhere.
If generations of Hollywood heist films have taught us anything, it’s that knocking off a bank vault is pretty easy. It usually starts with a guy and a stethoscope, but that never works, so the bad guys break out the cutting torch and burn their way in. But knowing how to harness that raw power means you’ve got to learn the basics of oxy-acetylene, and [This Old Tony]’s new video will get your life of crime off on the right foot.
In another well-produced video, [Tony] goes into quite a bit of detail on the mysteries of oxygen and acetylene and how to handle them without blowing yourself up. He starts with a tour of the equipment, including an interesting look at the internals of an acetylene tank — turns out the gas is stored dissolved in acetone in a porous matrix inside the tank. Working up the hoses, he covers the all-important flashback arrestors, the different styles of torches, and even the stoichiometry of hydrocarbon combustion and how adjusting the oxygen flow results in different flame types for different jobs. He shows how oxy-acetylene welding can be the poor man’s TIG, and finally satisfies that destructive urge by slicing through a piece of 3/8″ steel in under six seconds.
We’ve always wanted a decent oxy-acetylene rig, and [Tony] has convinced us that this is yet another must-have for the shop. There’s just so much you can do with them, not least of which is unsticking corroded fasteners. But if a blue wrench is out of your price range and you still want to stick metal together, you’ll want to learn how to braze aluminum with a propane torch.
Perhaps our future overlords won’t be made up of electrical circuits after all but will instead be soft-bodied like ourselves. However, their design will have its origins in electrical analogues, as with the Octobot.
The Octobot is the brainchild a team of Harvard University researchers who recently published an article about it in Nature. Its body is modeled on the octopus and is composed of all soft body parts that were made using a combination of 3D printing, molding and soft lithography. Two sets of arms on either side of the Octobot move, taking turns under the control of a soft oscillator circuit. You can see it in action in the video below.
Heat can be a hacker’s best friend. A little heat can help release a stubborn nut cleanly, and a lot of heat can melt a rusty bolt clean off. An oxy-acetylene torch is handy for these applications, but if you need a more portable setup, and you want enough heat to melt rocks, you might want to look into this field-expedient thermic lance.
Thermic lances have been around a long time in the demolition industry, where cutting steel quickly is a common chore. Commercial thermic lances are just a bundle of steel fuel rods which are set on fire while oxygen is blown down a consumable outer tube. The resulting flame can reach up to 4500°C with impressive results. In need of a similarly destructive device, [NightHawkInLight] came up with a super-simple lance – a small disposable tank of oxygen and regulator, a length of Tygon tubing, and a piece of 5/8″ steel brake line. No need for fuel rods in this design; the brake line provides both fuel and oxygen containment. As you can see in the video below, lighting the little lance without the usual oxy-acetylene torch is no problem – a “wick” of twisted steel wool is all that’s needed to get the torch going. The results are pretty impressive on both steel and rock.
You say you’re fresh out of brake line and still need some “don’t try this at home” action? No problem at all – just hit up the pantry for the materials needed for this tinfoil and spaghetti thermic lance.
Resin printing, it can be messy but you get really great resolution thanks to the optical nature of curing the sticky goo with light from a projector. Soon it will have a few more notches in its belt to lord over its deposition cousins: speed and lack of layers. A breakthrough in resin printing makes it much faster than ever before and pretty much eliminates layering from the printed structure.
The concept uses an oxygen-permeable layer at the bottom of the resin pool. This inhibits curing, and apparently is the source of the breakthrough. The resin is cured right on the border of this layer and allows for what is described as a continuous growth process rather than a layer-based approach. One of the benefits described is no need for resin to flow in as the part is extracted but we’re skeptical on that claim (the resin still needs to flow from somewhere). Still, for us the need to work with resin which is expensive, possibly messy, and has an expiry (at least when compared to plastic filament) has kept deposition as a contender. The speed increase and claims of strength benefits over layer-based techniques just might be that killer feature.
The technology is coming from a company called Carbon3D. They are branding it CLIP, or Continuous Liquid Interface Production. After the break you can see a video illustration of the concept (which is a bit too simple for our tastes) as well as a TED talk which the company’s CEO, [Joseph Desimone] gave this month. Of course there is also the obligatory time-lapse print demo.
So what do you think: game changer or not, and why do you feel that way? Let us know in the comments.