Wooden Cassette Tape Is A Veneer Stackup Seeking A Few Good Walkmen

While the days of audio cassette tapes are long over for almost everyone, magnetic tape still enjoys extensive use in some other realms such as large-scale data backup. Those that are still using it to store their tunes are a special subset of audio enthusiasts. [Frank] still has a working tape deck, and enthusiasm for classic non-vinyl sound. His homage to audio tape? Building a working cassette made (almost) entirely of wood.

The cassette is modeled on the formerly popular Maxell XL-II and the first versions of this build were modeled in paper. Once the precise dimensions of the enclosure were determined, [Frank] got to work building the final version from wood in a decidedly 2D process. He used a plotter to cut layers out of a wood veneer and glued them together one-by-one. The impressive part of this build is that the tape reel bearings are also made from wood, using a small piece as a race that holds the reels without too much friction.

Once everything was pieced together and glued up, [Frank] had a perfect working cassette tape made entirely from wood with the exception of the magnetic tape and a few critical plastic parts that handle the tape directly. The build is an impressive piece of woodworking, not unlike the solid wood arcade cabinet from a few days ago.

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3D Printing With VHS Tape Filament

If you have a pile of old VHS tapes collecting dust in your attic or basement that you know you’ll never watch again, either because all of those movies are available on DVD or a streaming service, or because you haven’t had a working VCR since 2003, there might be a way of putting them to good use in another way. With the miles of tape available in just a few cassettes, [brtv-z] shows us how to use that tape as filament for a 3D printer.

The first step of the build is to actually create the filament. He uses a purpose-built homemade press to spin several tapes into one filament similar to how cotton or flax is spun into yarn. From there the filament is simply fed into the 3D printer and put to work. The tape filament needs to be heated higher than a standard 3D printer filament so he prints at a much slower rate, but the resulting product is indistinguishable from a normal print except for the color. It has some other interesting properties as well, such as retaining its magnetism from the magnetic tape, and being a little more brittle than PET plastic although it seems to be a little stronger.

While the VHS filament might not be a replacement for all plastic 3D prints, it’s still a great use for something that would likely otherwise head straight to the landfill. There are some other uses for this magnetic tape as well, like if you wanted to build a DIY particle accelerator.

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Digging In The Dirt Yields Homebrew Inductors

Let’s say you’re stranded on a desert island and want to get the news from the outside world. You’ll have to build your own crystal radio, of course, but your parts bin is nowhere to be found and Digi-Key isn’t delivering. So you’ll need to MacGuyver some components. Capacitors are easy with a couple of pieces of tinfoil, and a rectifier can be made from a pencil and a razor blade. But what about an inductor?┬áSure, air-core inductors will work, but just because you’re marooned doesn’t mean you’ve abandoned your engineering principles. Luckily, you’ve read [AC7ZL]’s treatise of making inductors from dirt, and with sand in abundance, you’re able to harvest enough material to put together some passable ferrite-core inductors.

Obviously, making your own inductive elements isn’t practical even in fanciful and contrived situations, but that doesn’t make the doing of it any less cool. The story begins with a walk in the Arizona desert many years ago, where [AC7ZL], aka [H.P. Friedrichs], spied bands of dark sand shooting through the underlying lighter sediments. These bands turned out to be magnetite, one of many iron-bearing minerals found in the area. Using a powerful magnet from an old hard drive and a plastic food container, he was able to harvest magnetite sand in abundance and refine it with multiple washing steps.

After experimentally determining the material’s permeability — about 2.3 H/m — [AC7ZL] proceeded with some practical applications. He was able to make a bar antenna for an AM radio by packing the sand into a PVC pipe and rewinding the coils around it. More permanent cores were made by mixing the sand with polyester resin and casting it into bars. Toroids were machined from fat bars of the composite on a lathe, much to the detriment of the cutting tools used.

The full-length PDF account of [AC7ZL]’s experiments makes for fascinating reading — the inductive elements he was able to create all performed great in everything from a Joule Thief to a Hartley oscillator up to 27 MHz. We love these kinds of stories, which remind us of some of the work being done by [Simplifier] and others.

Scratch Built Magnetic Vise Stays Where You Need It

For those who might not have run into one before, a magnetic vise is used when you want to quickly anchor something to a metal surface at an arbitrary position. They’re often used to hold the workpiece down when machining, and can be a real time saver if a lot of repositioning is involved.

[Workshop From Scratch] recently wanted to put together one of these handy pieces of gear, and as we’ve come to expect from his channel, the finished product is an absolute beast. Starting with little more than scraps of metal, the video after the break takes the viewer on a fascinating journey that ends with some demonstrations of the vise in action.

Conceptually, this build is relatively simple. Start with a vise, put a hollow base on it, and fit it with powerful electromagnets that will anchor it down once you flip the switch. Technically you could just build a magnetic base and bolt a commercially available vise onto it, but that’s not how [Workshop From Scratch] does things.

Every element of the build is done by hand, from the pattern cut into the jaws to the t-handle nut driver that gets adapted into a very slick crank. Of particular interest is how much effort is put into grinding down the surface of the electromagnets so they are perfectly flush with the base of the vise. Incidentally, these beefy electromagnets were salvaged from automotive air conditioning compressors, so you might want to add that to your junkyard shopping list.

Eagle-eyed readers might recognize the surface [Workshop From Scratch] uses the vise on as the custom drill press table he built a few months ago. These videos are not only reminders of what you can accomplish when you’ve mastered the use of a few common tools, but just how much design and thought goes into the hardware many of us take for granted.

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[Ben Krasnow] Builds A Mass Spectrometer

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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Plasma-Powered Thrusters For Your Homebrew Satellite Needs

It seems as though every week we see something that clearly shows we’re living in the future. The components we routinely incorporate into our projects would have seemed like science fiction only a few short years ago, but now we buy them online and have them shipped to us for pennies. And what can say we’ve arrived in the future more than off-the-shelf plasma thrusters for the DIY microsatellite market?

Although [Michael Bretti] does tell us that he plans to sell these thrusters eventually, they’re not quite ready for the market yet. The AIS-gPPT3-1C series that’s currently under testing is designed for the micro-est of satellites, the PocketQube, a format with a unit size only 5 cm on a side – an eighth the size of a 1U CubeSat. The thrusters are solid-fueled, with blocks of Teflon, PEEK, or Ultem that are ablated by a stream of plasma. The gaseous exhaust is accelerated and shaped by a magnetic nozzle that’s integrated right into the thruster. The thruster is mounted directly to a PCB containing the high-voltage supplies and control electronics to interface with the PocketQube’s systems. The 34-gram thrusters have enough fuel for perhaps 500 firings, although that and the specifics of performance are yet to be tested.

If you have any interest at all in space engineering or propulsion systems, [Michael]’s site is worth a look. There’s a wealth of data there, and reading it will give you a great appreciation for plasma physics. We’ve been down that road a lot lately, with cold plasma, thin-film plasma deposition, and even explaining the mystery of plasmatic grapes.

Thanks to [miguekf] for the tip.

Magnetic Attraction Of Microduino MCookie Modules

We’ve seen countless different robot kits promoted for STEM education, every one of which can perform the robotic “Hello World” task of line following. Many were in attendance at Maker Faire Bay Area 2019 toiling in their endless loops. Walking past one such display by Microduino, Inc. our attention was caught by a demonstration of their mCookie modules in action: installing a peripheral module took less than a second with a “click” of magnets finding each other.

Many Arduino projects draw from an ecosystem of Arduino shields. Following that established path, Microduino had offered tiny Arduino-compatible boards and peripherals which connected with pins and headers just like their full-sized counterparts. Unfortunately their tiny size also meant their risk of pin misalignment and corresponding damage would be higher as well. mCookie addresses this challenge by using pogo pins for electrical contacts, and magnets to ensure proper alignment. Now even children with not-quite-there-yet dexterity can assemble these modules, opening up a market to a younger audience.

Spring loaded electric connections are a popular choice for programming jigs, and we’ve seen them combined with magnets for ideas like modular keyboards, and there are also LittleBits for building simple circuits. When packaged with bright colorful LEGO-compatible plastic mounts, we have the foundation of an interesting option for introductory electronics and programming. Microduino’s focus at Maker Faire was promoting their Itty Bitty Buggy, which at $60 USD is a significantly more affordable entry point to intelligent LEGO creations than LEGO’s own $300 USD Mindstorm EV3. It’ll be interesting to see if these nifty mCookie modules will help Microduino differentiate themselves from other LEGO compatible electronic kits following a similar playbook.