Build Your Own Class-E Musical Tesla Coil

April 26, 2024 by Lewin Day 1 Comment

We’ve all seen a million videos online with singing Tesla coils doing their thang. [Zach Armstrong] wasn’t content to just watch, though. He went out and built one himself! Even better, he’s built a guide for the rest of us, too!

His guide concerns the construction of a Class-E solid state Tesla coil. These are “underrated” in his opinion, as they’re simple, cheap, and incredibly efficient. Some say up to 95% efficient, in fact! It’s not something most Tesla coil fans are concerned with, but it’s nice to save the environment while making fun happy sparks, after all.

[Zach]’s guide doesn’t just slap down a schematic and call it good. He explains the theory behind it, and the unique features too. He uses an adjustable Schmitt trigger oscillator for the build, and he’s naturally given it an audio modulation capability because that’s a good laugh, too.

If you’ve ever wanted to convince you’re friends you’re incredibly smart and science-y, you can’t go wrong with a singing Tesla coil. This beats out Jacob’s ladder and most other plasma experiments for sheer mad scientist cred.

Have fun out there! Video after the break.

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Electromagnets Make Vertical CNC Cutter A Little Stickier

April 12, 2024 by Dan Maloney 10 Comments

Workholding is generally not a problem on a big CNC plasma cutter.; gravity does a pretty good job of keeping heavy sheet steel in place on the bed. But what if your CNC table isn’t a table? The answer: magnets — lots of magnets.

The backstory on this is a bit involved, but the condensed version is that [Lucas] needed a CNC plasma cutter big enough to cut full-sized sheets of steel, but lacked the floor space in his shop for such a beast. His solution was to build a custom CNC machine that stands more or less vertically, allowing him to cut full sheets in a mere fraction of the floor space. It’s a fantastic idea, one that he put a lot of effort into, but it’s not without its problems. Chief among them is the tendency for the sheet metal to buckle and bulge during cutting since gravity isn’t working for him, along with the pesky problem of offcuts slipping away.

To help hold things in place, [Lucas] decided to magnetize the bed of his cutter. That required winding a bunch of magnets, which is covered in the video below. Mass production of magnets turns out not to be as easy as you’d think. Also unexpected was the need to turn off magnets when the cutting torch is nearby, lest the magnetic field bork the cutting plasma. [Lucas] grabbed some code from the LinuxCNC forum that streams the gantry coordinates over serial and used an Arduino to parse those messages. When the torch is getting close to one of the magnets, a relay board cuts power to just that magnet. You can see it in action in the video below; at around the 18:15 mark, you can see the sheet bulging up a bit when the torch comes by, and sucking back down when it moves on.

The amount of work [Lucas] put into this project is impressive, and the results are fantastic. This isn’t the first time he’s relied on the power of magnets to deal with sheet steel, and it probably won’t be the last.

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20,000 Volt Plasma Knife Slices, Dices, And Sparks

February 9, 2024 by Tom Nardi 5 Comments

For the most part, here at Hackaday we’re more interested in how something was made than the backstory on why an individual actually put it together. Frankly, it’s not really our business. But we’ve been around long enough to know that practicality isn’t always the driving force. Some folks build things because they want to challenge themselves, others because there’s nothing commercially available that quite meets their needs. Of course, there’s another camp that just builds things to look cool.

In the case of the plasma-infused blade [Jay Bowles] recently put together for Plasma Channel, we imagine it was a bit from each column. The basic inspiration was to create something in the style of the “Energy Sword” from Halo, but the resulting electrified blade is no mere prop. Inside the 3D printed enclosure, it packs not only the electronics necessary to produce 20,000 volts from the built-in battery pack, but a fan to help push the resulting plasma down the length of the two-piece steel blade.

As you might expect, it took a few attempts to get there. In the video after the break, [Jay] shows off the design process and some earlier incarnations of the plasma knife that didn’t quite live up to expectations. While there were always some impressive sparks, the spacing of the blades and the output power of the miniature high-voltage generator both needed fine tuning before it resulted in the band of plasma he was aiming for.

Is there a practical use for such a thing? Well the spark between the blades can apparently be used to light stuff on fire, and of course, you can cut things with it. But realistically…no, not really. It just looks cool, which is fine by us.

Should you prefer your high-voltage experimentation to have a more clearly defined goal, you might be interested in the ongoing work [Jay] has been doing with ionic propulsion and magnetohydrodynamic drives (MHDs).

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Plasma Cutting And 3D Printing Team Up To Make Bending Thick Sheet Steel Easier

October 28, 2023 by Dan Maloney 7 Comments

Metalworking has always been very much a “mixed method” art. Forging, welding, milling, grinding; anything to remove metal or push it around from one place to another is fair game when you’ve got to make something fast. Adding in fancy new tools like CNC plasma cutting and computer-aided drafting doesn’t change that much, although new methods often do call for a little improvisation.

Getting several methodologies to work and play well together is what [tonygoacher] learned all about while trying to fabricate some brackets for an electric trike for next year’s EMF Camp. The parts would have been perfect for fabrication in a press brake except for the 4 mm thickness of the plate steel, which was a little much for his smallish brake. To make the bending a little easier, [tony] made a partial-thickness groove across the plasma-cut blank, by using a reduced power setting on the cutter. This worked perfectly to guide the brake’s tooling, but [tony] ran into trouble with more complicated bends that would require grooves on both sides of the steel plate.

His solution was to 3D print a couple of sacrificial guide blocks to fit the bed of the press brake. Each guide had a ridge to match up with a guide groove, this allowed him to cut his partial grooves for both bends on the same side of the plate but still align it in the press brake. Yes, the blocks were destroyed in the process, but they only took a few minutes to print, so no big deal. And it’s true that the steel tore a little bit when the groove ended up on the outside radius of the bend, but that’s nothing a bead of weld can’t fix. Good enough for EMF is good enough, after all.

The brief video below shows the whole process, including [tony]’s interesting SCARA-like CNC plasma cutter, which we’re a little in love with now. This isn’t the first time we’ve seen 3D prints used as tools in metalworking, of course, but we picked up some great tips from this one. Continue reading “Plasma Cutting And 3D Printing Team Up To Make Bending Thick Sheet Steel Easier” →

High Voltage Turns Welder Into Plasma Cutter

October 24, 2023 by Bryan Cockfield 29 Comments

For doing basic steel welding, most of us will reach for a MIG welder. It might not be the best tool for every welding job, but it’s definitely the most accessible since they tend to use only basic parts, easy-to-find gas, and can run from a standard electrical outlet. A plasma cutter isn’t as common, and while they’re certainly useful, [Rulof] wanted to forgo the expense of buying one off the shelf. Instead, he used parts of an old welder and a few other odds and ends to build his own plasma cutter.

The welder he’s working from in this project uses low-voltage alternating current to drive the welding process, but since a plasma cutter ionizes gas it needs high-voltage direct current. A 200 A bridge rectifier with some heat sinks from a Mac and an old stereo get this job done, but that’s not the only step in the process. A driver board and flyback transformer is used to generate the high voltage needed for the cutting head. There are some DIY circuit protection and safety features built in as well, including a spark gap using two nails, galvanic isolation from a transformer built from copper pipe, and some filtering coils made from old copper wire and iron bars.

With everything connected to the old welding machine and some pressurized air inside to push out the plasma, [Rulof] has a functional plasma cutter that can make short work out of a variety of metals at a fraction of the cost of a commercial tool. With the cutting tool finished, we’d recommend mounting it to a home-built CNC machine next.

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Simple Add-On Makes Cheap Plasma Cutter Suitable For CNC Use

September 30, 2023 by Dan Maloney 15 Comments

Plasma cutters are ridiculously cheap these days, just cruise by the usual online sources or your local Harbor Freight if you’ve got any doubt about that. But “cheap” and “good” don’t always intersect on a Venn diagram, and even when they do, not every plasma cutter is suitable for use on the spanking new CNC table you’re building. But luckily, there’s a mod for that.

As [Jake von Slatt] explains it, there are two kinds of plasma cutters on the market: high-frequency (HF) start and pilot arc start. The basic difference is that HF start cutters, which comprise the majority of cheap cutters on the market, need direct electrical contact with the workpiece to start the cutting action. Pilot arc torches, which are more suitable for CNC cutters, can strike the arc through a separate conductor without the need to contact the workpiece.

While there are homebrew bodges that claim to turn an HF torch into a pilot arc, [Jake]’s approach is a bit more complicated, and necessarily so. His add-on box intercepts the ground clamp — which is actually the positive conductor for plasma cutting — and switches it through a heavy-duty HVAC contactor. The 24 VDC coil of the contactor is controlled by a homebrew current sensor made from a huge toroid ferrite core wrapped with 20 turns of 6 AWG welding wire.

Before winding, the core is split in two and epoxied back together with a small magnetic reed switch bridging the gap. A simple 24 VDC power supply runs the whole thing. When the torch starts, the nozzle is connected to ground through the contactor, but as soon as the arc strikes and starts pulling cutting current through that toroid, the magnetic field closes the reed switch, which opens the contactor via a small DC relay. This removes the connection between the nozzle and ground, leaving the plasma to carry all the cutting current.

We’ve featured many, many CNC plasma cutter tables before, but most of these builds have concentrated on the table more than the cutter. It’s a refreshing change to get some insider tips on what kinds of cutters work best, and how to adapt what you’ve got for the job.

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NASA’s Parker Probe Gets Front Row Seat To CME

September 25, 2023 by Tom Nardi 10 Comments

A little over a year ago, and about 150 million kilometers (93 million miles) from where you’re currently reading this, NASA’s Parker Solar Probe quietly made history by safely flying through one of the most powerful coronal mass ejections (CMEs) ever recorded. Now that researchers have had time to review the data, amateur space nerds like ourselves are finally getting details about the probe’s fiery flight.

Launched in August 2018, the Parker Solar Probe was built to get up close and personal with our local star. Just two months after liftoff, it had already beaten the record for closest approach to the Sun by a spacecraft. The probe, with its distinctive solar shield, has come within 8.5 million kilometers (5.3 million miles) of its surface, a record that it’s set to break as its highly elliptical orbit tightens.

As clearly visible in the video below, the Parker probe flew directly into the erupting CME on September the 5th of 2022, and didn’t get fully clear of the plasma for a few days. During that time, researchers say it observed something that had previously only been theorized — the interaction between a CME and the swirling dust and debris that fills our solar system.

According to the Johns Hopkins Applied Physics Laboratory (APL), the blast that Parker flew through managed to displace this slurry of cosmic bric a brac out to approximately 9.6 million km (6 million miles), though the void it created was nearly instantly refilled. The researchers say that better understanding how a CME propagates through the interplanetary medium could help us better predict and track potentially dangerous space weather.

It’s been a busy year for the Parker Solar Probe. Back in June it announced that data from the craft was improving our understanding of high-speed solar winds. With the spacecraft set to move closer and closer to the Sun over the next two years, we’re willing to bet this isn’t the last discovery to come from this fascinating mission.

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