Keeping Magnetized Marbles from Stopping the Music

Take a couple of thousand steel balls, add a large wooden gear with neodymium magnets embedded in it, and what do you get? Either the beginnings of a wonderful kinetic music machine, or a mess of balls all stuck together and clogging up the works.

The latter was the case for [Martin], and he needed to find a way to demagnetize steel balls in a continuous process if his “Marble Machine X” were to see the light of day. You may recall [Martin] as a member of the band Wintergatan and the inventor of the original Marble Machine, a remarkable one-man band that makes music by dropping steel balls on various instruments. As fabulous a contraption as the original Marble Machine was, it was strictly a studio instrument, too fragile for touring.

Marble Machine X is a complete reimagining of the original, intended to be robust enough to go on a world tour. [Martin] completely redesigned the lift mechanism, using magnets to grip the balls from the return bin and feed them up to a complicated divider. But during the lift, the balls became magnetized enough to stick together and no longer roll into the divider. The video below shows [Martin]’s solution: a degausser using magnets of alternating polarity spinning slowly under the sticky marbles. As a side note, it’s interesting and entertaining to watch a musician procrastinate while debugging a mechanical problem.

We can’t wait to see Marble Machine X in action, but until it’s done we’ll just settle for [Martin]’s other musical hacks, like his paper-tape programmed music box or this mashup of a synthesizer and a violin.

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Flying the Friendly Skies with A Hall Effect Joystick

There are plenty of PC joysticks out there, but that didn’t stop [dizekat] from building his own. Most joysticks measure position mechanically using potentiometers or encoders. Only a few high-end models use Hall effect sensors. That’s the route [dizekat] took.

Hall effect sensors are non-contact devices which measure magnetic fields. They can be used to measure the position and orientation of a magnet. That’s exactly how [dizekat] is using a trio of sensors in his design. The core of the joystick is a universal joint from an old R/C car. The center section of the joint (called a spider) has two one millimeter thick disc magnets glued to it. The Hall sensors themselves are mounted in the universal itself. [Dizekat] used a small piece of a chopstick to hold the sensors in position while he found the zero point and glued them in. A third Hall effect sensor is used to measure a throttle stick positioned on the side of the box.

An Arduino micro reads the sensors and converts the analog signal to USB.  The Arduino Joystick Library by [Matthew Heironimus] formats the data into something a PC can understand.

While this is definitely a rough work in progress, we’re excited by how much [dizekat] has accomplished with simple hand tools and glue. You don’t need a 3D printer, laser cutter, and a CNC to pull off an awesome hack!

If you think Hall effect sensors are just for joysticks, you’d be wrong – they work as cameras for imaging magnetic fields too!

Electromagnet-Powered Pendulum

We’re always happy to see hackers inspired to try something different by what they see on Hackaday. To [SimpleTronic] has a project that will let you stretch your analog electronics skills in a really fun way. It’s an electromagnet pendulum analog circuit. Whether you’re building it, or just studying the schematics, this is a fun way to brush up on the non-digital side of the craft.

The pendulum is a neodymium magnet on the head of a bolt, dangling on a one foot aluminium chain. Below, a Hall Effect sensor rests atop an electromagnet — 1″ in diameter, with 6/8″ wire coiled around another bolt. As the pendulum’s magnet accelerates towards the electromagnet’s core, the Hall effect sensor registers an increase in voltage. The voltage peaks as the pendulum passes overhead, and as soon as the Hall Effect sensor detects the drop in voltage, the electromagnet flicks on for a moment to propel the pendulum away. This circuit has a very low power consumption, as the electromagnet is only on for about 20ms!

The other major components are a LM358N op-amp, a CD4001B quad CMOS NOR gate, and IRFD-120 MOSFET. [SimpleTronic] even took the time to highlight each part of the schematic in order to work through a complete explanation.

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Fail of The Week — Accidental Demagnetization

There’s a trick in the world of plastic enclosures. The threaded insert is a small cylinder of metal with threads on the inside and a rough edge on the outside. To make a plastic part with a hole for securely connecting bolts that can be repeatedly screwed without destroying the plastic, you take the threaded insert and press it (usually with the help of a soldering iron to heat the insert)  into a hole that’s slightly smaller than the insert. The heat melts the plastic a little bit and allows for the insert to go inside. Then when it cools the insert is snugly inside the plastic, and you can attach circuit boards or other plastic parts using a bolt without stripping the screw or the insert. We’ve seen Hackaday’s [Joshua Vasquez] installing threaded inserts with an iron, as well as in a few other projects.

This trick is neat. And I’ve now proven that it does not work with neodymium magnets.

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Your Work Won’t Move with a Magnetic Drill Press Vise

Setting up your workpiece is often the hardest part of any machining operation. The goal is to secure the workpiece so it can’t move during machining in such a way that nothing gets in the way of the tooling. Magnetic chucks are a great choice for securely and flexibly holding down workpieces, as this simple shop-built electromagnetic vise shows.

It looks like [Make It Extreme] learned a thing or two about converting microwave oven transformers to electromagnets when they built a material handling crane for the shop. Their magnetic vise, designed for a drill press but probably a great choice for securing work to a milling machine, grinder, or even a CNC router, has a simple but sturdy steel frame. Two separate platforms slide on the bed of the vise, each containing two decapitated MOTs. Wired to mains power separately for selective control and potted in epoxy, the magnets really seem to do the job. The video below shows a very thick piece of steel plate cantilevered out over one magnet while having a hole cut; that’s a lot of down force, but the workpiece doesn’t move.

Like the idea of a shop-made vise but would rather go the old-fashioned way? Check out [Make It Extreme]’s laminated bench vise, which also makes an appearance in this video.

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Magnet Implants, Your Cyborg Primer

What would you do to gain a sixth sense? Some of us would submit to a minor surgical procedure where a magnet is implanted under the skin. While this isn’t the first time magnet implants have been mentioned here on Hackaday, [The Thought Emporium] did a phenomenal job of gathering the scattered data from blogs, forum posts, and personal experimentation into a short video which can be seen after the break.

As [The Thought Emporium] explains in more eloquent detail, a magnet under the skin allows the implantee to gain a permanent sense of strong magnetic fields. Implantation in a fingertip is most common because nerve density is high and probing is possible. Ear implants are the next most useful because oscillating magnetic fields can be translated to sound.

For some, this is merely a parlor trick. Lifting paper clips and messing with a compass are great fun. Can magnet implants be more than whimsical baubles?

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An Environmentally Conscious, Solar-Powered Throwie

The basic throwie is a a type of street art/graffiti/vandalism — depending on where you stand — consisting of a coin cell, an led, and a magnet taped together. Seeking to be a slightly more eco-friendly troublemaker, [Alaric Loftus] has kindly put together an Instructable on how to build a solar-powered throwie!

In order to be the best maker of mischief possible, [Alaric Loftus] tried a number of different products to find one that was hackable,  supplied the right voltage, had the right form factor, and cheap enough to literally throw away. Turns out, garden path lights hit that sweet spot. Once [Alaric Loftus] has drilled a hole in the light and opened it up, de-soldering the stock LED, attaching some leads to the contacts and sticking it into the freshly-drilled hole is simply done. Hot-gluing a strong magnet on the bottom completes the throwie.

[Alaric Loftus] also advises that drilling the LED hole slightly smaller and sealing up any cracks with hot glue will strengthen its water resistance — because if it’s worth doing, it’s worth doing it right.

We’ve featured some really cooleven creepy — takes on the throwie concept, but please don’t contribute any further to e-waste buildup.