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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Nifty MIG Welder Built From Scrap

October 11, 2023 by Lewin Day 29 Comments

A MIG welder is a great tool to have. With machine fed wire and gas protecting the arc, it can make it easy to weld well without requiring a lot of manual skill from the operator. [PROFESSOR PARDAL BRASIL] decided to build his own MIG welder using scrap parts, and it’s an inspiring bit of work.

The build is along the lines of so many YouTube contraptions, using bits and pieces thrown together in oddball ways. A windscreen wiper motor is used to create a wire feeder, with jammed-up ball bearings acting as rollers. Speed control of the wiper motor appears to be via a variable resistor created by moving two plates closer together in a bath of salt water. This enables the wire feed rate to be easily controlled, albeit in a wet and messy fashion. The build includes a device for producing carbon dioxide for use as shielding gas, too. This is achieved by mixing a solution of water and bicarbonate soda with vinegar, and then pumping the resulting carbon dioxide into an inner tube for storage. The power supply for actually creating an arc comes courtesy of car batteries.

The resulting welder is janky as all heck, but it does successfully weld some steel plates together. Job done, as they say. Video after the break. Continue reading “Nifty MIG Welder Built From Scrap” →

An exploded diagram of the spot welder. Shown are the capacitor bank, trigger, 12 V relay, DC power input, power out, step up converter, voltmeter, industrial SCR module, and capacitor bank.

Hackaday Prize 2022: A Not-So-Smart Spot Welder

October 17, 2022 by Navarre Bartz 5 Comments

DIY spot welders often use high-powered components that can be a bit frightening, given the potential for dangerous malfunctions. [Wojciech “Adalbert” J.] designed his capacitive discharge spot welder to be safe, easy to build, and forego the microcontroller.

Many projects work great with just a single Li-ion cell, but when you need more power, you’ve got to start connecting more cells together into a battery. [Wojciech]’s spot welder is designed to be just powerful enough to weld nickel tabs onto a cell without any overkill. The capacitor bank uses nineteen Nichicon UBY 7500uF/35V capacitors, all wired in parallel using solder wick saturated with solder. They sit atop on a perfboard with metallicized holes to carry the high current.

[Wojciech] has detailed every step of building the welder, including changes to the off-the-shelf relay board and adding a potentiometer to the step-up converter board. The level of detail makes this seem like a good starting place if you’re hoping to hop into the world of DIY spot welders. Safe is always a relative term when dealing with high powered devices, so be careful if you do attempt this build!

DIY spot welders have graced these digital pages many times, including this one built with safety in mind, and this other one that was decidedly not.

Robert Dunn holds a button in his hand for controlling a spot welder

Gorgeous Battery Welder Hits The Spot

September 14, 2021 by Ryan Flowers 32 Comments

Raise you’re hand if you’ve ever soldered directly to a battery even though you know better. We’ve all been there. Sometimes we get away with it when we have a small pack and don’t care about longevity. But when [Robert Dunn] needed to build a battery pack out of about 120 Lithium Ion cells, he knew that he had to do it The Right Way and use a battery spot welder. Of course, buying one is too simple for a hacker like [Robert]. And so it was that he decided to Build a Spot Welder from an old Microwave Oven and way too much mahogany, which you can view below the break.

A Battery Cell with a spot welding tab attached — Spot Welding leaves two familiar divots in the attached tab, which can be soldered or welded as need.

For the unfamiliar, a battery spot welder is the magical device that attaches tabs to rechargeable batteries. You’ll notice that all battery packs with cylindrical cells have a tab with two small dimples. These dimples are where high amperage electricity quickly heats the battery terminal and the tab until they’re red hot, welding them together. The operation is done and over in less than a second, well before any heat damage can be done. The tab can then be soldered to or spot welded to another cell.

One of the most critical parts of spot welding batteries is timing. While [Robert Dunn] admits that a 555 timer or even just a manual switch and relay could have done the job, he opted for an Arduino Uno with a 4 character 7 segment LED display that shows the welding time in milliseconds. A 3d printed trigger and welder handle wrap up the hardware nicely.

The build is topped off by a custom mahogany enclosure that is quite a bit overdone. But if one has the wood, the time, the tools and skills (and a YouTube channel perhaps?) there’s no reason not to put in the extra effort! [Robert]’s resulting build is almost too nice, but it’ll certainly get the job done.

Of course, spot welders are almost standard fare here at Hackaday, and we’ve covered The Good, The Bad, and The Solar. Do you have a battery welder project that deserves a spot in Hackaday’s rotation? By all means, send it over to the Tip Line!

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Ambitious Spot Welder Really Pushes The Amps

April 16, 2021 by Dan Maloney 18 Comments

On the face of it, a spot welder is a simple device. If you dump enough current through two pieces of metal very quickly, they’ll heat up enough to melt and fuse together. But as with many things, the devil is in the details, and building a proper spot welder can be as much about addressing those details as seeing to the basics.

We haven’t featured anything from our friends over at [Make It Extreme], where they’re as much about building tools as they are about using them to build other things, if not more so. We expect, though, that this sturdy-looking spot welder will show up in a future video, because it really looks the business, and seems to work really well. The electronics are deceptively simple — just rewound microwave oven transformers and a simple timer switch to control the current pulse. What’s neat is that they used a pair of transformers to boost the current considerably — they reckon the current at 1,000 A, making the machine capable of welding stock up to 4 mm thick.

With the electrical end worked out, the rest of the build concentrated on the housing. A key to good-quality spot welds is solid physical pressure between the electrodes, which is provided by a leverage-compounding linkage as well as the long, solid-copper electrodes. We’ve got to say that the sweep of the locking handle looks very ergonomic, and we like the way closing down the handle activates the current pulse. Extra points for the carbon-fiber look on the finished version. The video below shows the build and a demo of what it can do.

Most of the spot welders we see are further down the food chain than this one, specialized as they are for welding battery packs and the like. We do recall one other very professional-looking spot welder, though.

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Improbably Cheap Pocket Welder Gets An ESP32 Makeover

November 4, 2019 by Dan Maloney 25 Comments

If you move in certain shady circles, you may have noticed the crop of improbably cheap “pocket welders” popping up on the market these days. They’re all variations on a theme, most with wildly optimistic specs minimal accessories of the lowest possible quality. But their tiny size and matching price make them irresistible to the would-be welder, as well as attractive to hardware hackers.

With a 220-V outlet in the garage waiting to be filled and well-knowing the risks, [Mr. RC-Cam] purchased one of these diminutive welding machines. Its shortcomings were immediately apparent, and a complete rework of the welder was undertaken. After addressing safety issues like the lack of a ground connection, [Mr. RC-Cam] added a color-matched 3D-printed hood to house a fancy new LCD touchscreen display. Backing that up is an ESP32 with Bluetooth, which supports remote control via a key fob. He also added a current sense board that uses the welder’s current shunt to measure welding current. Expediently calibrated using a waffle iron and a milli-ohmmeter, the sensor showed that the 200A max advertised for the welder was more like 100A. He tried adding some big electrolytics to fix the current issues, but no dice. With a decent stinger and ground clamp, the modified welder is good enough for his needs, and much was learned in the process. We call that a hacking win.

As an aside, [This Old Tony] recently did a review on a similar welder if you want more details on the internals. We also covered the conversion of a buzz-box to a TIG welder recently, should that be more your style.

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Is A Cheap Inverter Welder Worth It?

September 23, 2019 by Jenny List 138 Comments

We’ve all seen cheap welders for sale from the usual online sources, small inverter stick welders for a very tempting price. But are they any good? When my local supermarket had one in its offers aisle, I took the plunge and placed it in my cart alongside the usual week’s supply of Marmite. That was some time around the start of the year.

Does Your Supermarket Sell Welders?

My Workzone welder from the supermarket.

What I’d bought from my local Aldi was a Workzone WWIW-80, an 80 A unit that had cost me somewhere just over £60 (about $75), and came with welding leads and a rather poor quality face shield. The German discount supermarket chains specialise in periodic offers on all kinds of interesting things, so a very similar unit has also been for sale with a Parkside brand from their competitor Lidl. These small inverter welders are fairly generic, so they can be found with a variety of brands and specifications at a lower price online if you don’t mind forgoing the generous Aldi 3 year guarantee. The cheapest I’ve seen was about £35, or $44, but that price included only the inverter, without welding leads.

As a working blacksmith my dad has had a high-quality inverter welder since the 1990s, so my frame of reference is based upon that. He tried one of the first tiny inverters when they originally came to market in the last decade, but it couldn’t take the demands of a professional welder and packed up. I thus didn’t have high expectations of this unit, but I needed one of my own and for the price it was worth the punt. I’ve used it for occasional general purpose heavy welding tasks, repairing bits of farm machinery and fittings, and rebuilding some steps on a narrowboat in 7 mm plate. It’s acquitted itself well in those tasks, in that I am not a skilled welder and my work isn’t the tidiest, but it’s allowed me to do a satisfactory job.

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