Aspiring TIG welders very quickly learn the importance of good tungsten electrode grinding skills. All it takes is a moment’s distraction or a tiny tremor in the torch hand to plunge the electrode into the weld pool, causing it to ball up and stop performing its vital function. Add to that the fussy nature of the job — tungstens must only be ground parallel to the long axis, never perpendicular, and at a consistent angle — and electrode maintenance can become a significant barrier to the TIG beginner.
A custom tungsten grinder like this one might be just the thing to flatten that learning curve. It comes to us by way of [The Metalist], who turned an electric die grinder into a pencil sharpener for tungsten electrodes. What we find fascinating about this build is the fabrication methods used, as well as the simplicity of the toolkit needed to accomplish it. The housing of the attachment is built up from scraps of aluminum tubing and sheet stock, welded together and then shaped into a smooth, unibody form that almost looks like a casting. Highlights include the mechanism for adjusting the angle of the grind as well as the clever way to slit the body of the attachment so it can be clamped to the nosepiece of the die grinder. We also thought the inclusion of a filter to capture tungsten dust was a nice touch; most TIG electrodes contain a small amount of lanthanum or thorium, so their slight radioactivity is probably best not inhaled.
Video blogger and display technology guru [Fran Blanche] has discovered a splendid retro-tech alphanumeric display from 1910. (Video, embedded below.)
We have always enjoyed her forays into old and unusual displays, including her project researching and reverse engineering an Apollo DSKY unit. This time [Fran] has dug up an amazing billboard from the early 20th century. It was built by the Rice Electric Display Company of Dayton Ohio, and operated in Herald Square for about two years. Requiring $400,000 in 1910-US-dollars to build, this was clearly an Herculean effort for its day and no doubt is the first example of selling advertising time on a computer-controller billboard. It boasts characters that are about 1.3 m tall and 1 m wide which can display letters, numbers, and various punctuation and symbols. These are arrayed into a 3-line 18-character matrix that is about 27 x 4 meters, and that’s up only a third of the total billboard, itself an illuminated and dynamic work of art.
There are quite a few tantalizing details in the video, but a few that jumped out at us are the 20,000 light bulbs, the 40 Hz display update rate, the 150 km of wire used and the three month long installation time. We would really like to learn more about these two 7.5 kW motorized switch controllers, how were they programmed, how were the character segments arranged, what were their shapes?
In the video, you can see triangles arranged in some pattern not unlike more modern sixteen segment displays, although as [Fran] points out, Mr Rice’s characters are more pleasing. We hope [Fran] can tease out more details for a future video. If you have any ideas or knowledge about this display, please put them in the comments section below. Spoiler alert after the video…
Having a laser cutter these days isn’t a big deal. But [Chunlei Guo], a professor at the University of Rochester, has a powerful femto-second pulse laser and used it to create what might be the perfect solar absorber. You can see a video about the work, below.
It stands to reason that white materials reflect most light and therefore absorb less energy than black materials — this is part of what makes a radiometer work. Tungsten, in particular, is a good metal for absorbing solar power, but this new laser treatment — which builds nanostructures on the surface of the metal — increases efficiency by 130% compared to untreated tungsten.
In graduate school, I had a seminar course where one of the sections was about X-ray crystallography. I was excited, because being able to discern the three-dimensional structure of macromolecules just by shining X-rays on them seemed like magic to me. And thanks to a lackluster professor, after the section it remained just as much of a mystery.
If only I’d had [Steve Mould] as a teacher back then. His latest video does an outstanding job explaining X-ray crystallography by scaling up the problem considerably, using the longer wavelength of light and a macroscopic target. He begins with a review of diffraction patterns, those alternating light and dark bands of constructive and destructive interference that result when light shines on two closely spaced slits — the famous “Double-Slit Experiment” that showed light behaves both as a particle and as a wave and provided our first glimpse of quantum mechanics. [Steve] then doubled down on the double-slit, placing another pair of slits in the path of the first. This revealed a grid of spots rather than alternating bands, with the angle between axes dependent on the angle of the slit pairs to each other.
Photograph 51, an X-ray crystallogram of the B-form of DNA, by Gosling and Franklin, 1952. Source: Wikipedia
To complete the demonstration, [Steve] then used diffraction to image the helical tungsten filament of an incandescent light bulb. Shining a laser through the helix resulted in a pattern bearing a striking resemblance to what’s probably the most famous X-ray crystallogram ever: [Rosalind Franklin]’s portrait of DNA. It all makes perfect sense, and it’s easy to see how the process works when scaled down both in terms of the target size and the wavelength of light used to probe it.
Hats off to [Steve] for making something that’s ordinarily complex so easily understandable, and for filling in a long-standing gap in my knowledge.
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.
State-of-the-art welding machines aren’t cheap, and for good reason: pushing around that much current in a controlled way and doing it over an entire workday takes some heavy-duty parts. There are bargains to be found, though, especially in the most basic of machines: AC stick welders. The familiar and aptly named “tombstone” welders can do the business, and they’re a great tool to learn how to lay a bead.
Tombstones are not without their drawbacks, though, and while others might buy a different welder when bumping up against those limits, [Greg Hildstrom] decided to hack his AC stick welder into an AC/DC welder with TIG. He details the panoply of mods he made to the welder, from a new 50 A cordset made from three extension cords where all three 12 gauge wires in each cord are connected together to make much larger effective conductors, to adding rectifiers and a choke made from the frame of a microwave oven transformer to produce DC output at the full 225 A rating. By the end of the project the tombstone was chock full of hacks, including a homemade foot pedal for voltage control, new industry-standard connectors for everything, and with the help of a vintage Lincoln “Hi-Freq” controller, support for TIG, or tungsten inert gas welding. His blog post shows some of the many test beads he’s put down with the machine, and the video playlist linked below shows highlights of the build.
This isn’t [Greg]’s first foray into the world of hot metal. A few years back we covered his electric arc furnace build, powered by another, more capable welder.
Hundreds of years from now, the story of humanity’s inevitable spread across the solar system will be a collection of engineering problems solved, some probably in heroic fashion. We’ve already tackled a lot of these problems in our first furtive steps into the wider galaxy. Our engineering solutions have taken humans to the Moon and back, but that’s as far as we’ve been able to send our fragile and precious selves.
While we figure out how to solve the problems keeping us trapped in the Earth-Moon system, we’ve sent fleets of robotic emissaries to do our exploration by proxy, to make the observations we need to frame the next set of engineering problems to be solved. But as we reach further out into the solar system and beyond, our exploration capabilities are increasingly suffering from communications bottlenecks that restrict how much data we can ship back to Earth.
We need to find a way to send vast amounts of data back as quickly as possible using as few resources as possible on both ends of the communications link. Doing so may mean turning away from traditional radio communications and going way, way up the dial and developing practical means for communicating with X-rays.