Electromagnets Make Vertical CNC Cutter A Little Stickier

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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High Voltage Turns Welder Into Plasma Cutter

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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Fiery Torch Build Is Remarkably Stylish

Hollywood movies, RPGs, and Dungeons and Dragons campaigns are all full of flaming torches. They’re a typical source of light in scenarios where electrical solutions simply aren’t available. [Wesley Treat] decided to build a rather attractive ceremonial torch of his own design, showing off his impressive crafting skills in the process.

The torch ignited a pretty rad sculpture.

The build starts with a foam simulacra that helps [Wesley] rough out the general shape of the torch. It’s a little shorter and stubbier than an Olympic torch might be, for reference. The main body of the torch is then hewn out of stout wooden blocks with the aid of a bandsaw with a nifty angle-adjustable cutting bed. A torch was then used to heat and bend steel strip  to make an attractive and heat-resistant flame shroud to sit on top. A wad of fuel-soaked material installed inside the shroud serves as the actual flaming compoment.

[Wesley] built the torch for the Maker Burn at Maker Camp in upstate New York. It did a plenty good job of helping burn down the giant scrap wood jackalope  sculpture built for the event. We do love the fire and the flames around these parts. Video after the break.

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Robert Murray Smith Discusses Rivets and Riveting

Old School Fastener Tutorial Is Riveting

Whether you’re making, repairing, or hacking something together, we all need fastners. Screws, nuts and bolts, and pop rivets are handy sometimes. Various resins and even hot glue are equally useful. In some cases however the right fastener for the job eludes us, and we need another trick up our sleeve.

[Robert Murray Smith] found himself in such a position. His goal was to join two pieces of aluminum that need a nice finish on both sides. Neither glue, pop rivets, screws, nuts or bolts would have been appropriate.  [Robert] is always flush with ideas both new and old, and he resorted to using an old school fastener as explained as explained in his video “How To Make And Use Rivets“.

In the video below the break, [Robert] goes into great detail about making a simple rivet die from a 5mm (3/16”) piece of flat steel, creating the rivet from a brass rod, and then using the flush rivet to join two pieces of aluminum. The simple tooling he uses makes the technique available to anybody with a propane torch, a vise, some basic tools, and a simple claw hammer. We also appreciate [Robert]’s discussion of cold riveting, hot riveting, and annealing the rivets as needed.

Not only is riveting a technique thousands of years old, its advancement and application during the Industrial Revolution enabled technologies that couldn’t have existed otherwise. Hackaday’s own [Jenny List] did a wonderful write up about rivets in 2018 that you won’t want to miss!

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We Would Not Want To Be Stormtroopers Right Now

Humanity is another step closer to a fantasy-accurate lightsaber thanks to Hackaday alumnus [James Hobson] at Hacksmith. Their proto-saber cuts through (cosplay) stormtrooper armor, (foam) walls, and a (legit!) 1/4″ (6.35mm) steel plate. For so many reasons, we want to focus on the blade and handle. (Video, embedded below.)

The blade is a plasma stream designed for glassworking and burns a propane/oxygen mix with almost no residue, but the “blade” stays in a tight cylinder shape. With a custom PCB hosting a mixing controller, the blade extends and retracts like in the movies. The handle is not a technical marvel; it is an artistic wonder and if you want to see some machining eye-candy, check out the first video after the break. The second video demonstrates just how much damage you can do with a 4000° Fahrenheit tube of portable plasma.

You won’t be dueling anyone just yet, since there is no magnetic field shaping the blade like the ones [Lucas] envisioned. Unfortunately, you can’t block anything more substantial than a balloon sword since solid material will pass right through it, but it will suffer a mighty burn in the process. Lightsabers are a fantasy weapon, but the collective passion of nerds have made it as real as ever, and the Guinness folks give credibility to this build.

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Emergency Torch Runs Without Batteries

It’s always good to have a torch on hand for emergencies. Unfortunately, sometimes these torches can be forgotten, and wind up with dead batteries when you need them most. For those cases, this build from [techrallyofficial] is just the ticket.

Instead of a battery, the torch relies on a 1.5 farad supercapacitor to store energy. The body of the torch is constructed out of PVC pipe and fittings, and packs strong neodymium magnets inside. A coil of wire wrapped is formed around an old solder spool, which, when shaken past the magnets, generates a current. This is rectified with a series of diodes and charges the supercapacitor, powering the light.

It’s a classic design that is available commercially, but it’s one easily replicated in the home shop, too. It would make a great educational project, particularly as students would be left with a useful device to take home at the end of the lesson. We’ve seen others resurrect commercial builds with upgrades, too. Video after the break.

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Mini Flickering Torch Effect Uses Neither Wires Nor Solder

Cross section of pillar model.

[ROBAGON] makes miniature, 3D-printable gaming terrain and features like these stone pillars with flickering torch. His model isn’t free to download (though it’s under $2 at the time of writing), but the part that impressed us was his clever way of using electric tea lights to create a flickering torch effect without needing any soldering or wiring whatsoever.

His solution was to make the base of the pillar large enough to fit an electric tea light, which uses a flickering LED to simulate a candle flame. The molded plastic “flame” is removed from the tea light and placed in the torch sconce, while the tea light itself goes into the base. A short segment of clear acrylic rod is used as a light pipe, running from the tea light’s LED to the base of the torch.

It’s a simple, effective, and economical solution that doesn’t require running or soldering a single wire and you can see it work in the brief video embedded below. Now all that’s missing for those Dungeons & Dragons sessions is this custom calculator.

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