Plasma Cutter Gets CNC Treatment At Low Cost

May 3, 2024 by Bryan Cockfield 8 Comments

[Daniel] has been metalworking on a budget for a while now. Originally doing things like plasma cutting on old bricks, he used his original plasma cutter to make an appropriate plasma cutting table complete with a water bath which we presume was not only safer but better for his back. Since then he’s stepped up a little more with what might be the lowest-cost CNC plasma cutter that can reliably be put together.

The CNC machine uses a handheld plasma cutting torch as its base, which uses a blowback start mechanism making it usable in an automated CNC setup without interfering with the control electronics. This is a common issue with other types of plasma cutters not originally meant for CNC. The torch head only needs slight modifications to fit in a 3D printed housing designed for the CNC machine which involves little more than slightly changing the angle of the incoming copper tubing and wire and changing the location of the trigger.

With those modifications done, the tool head is ready to be mounted to the CNC machine. [Daniel] has put together a bill of materials for building the entire project for less than $400, which includes the sub-$200 plasma cutter. It’s an impressive bit of sleuthing to get the price down this low, but if you’re still using your plasma cutter by hand on bricks in the yard like [Daniel] used to do make sure to check out that DIY plasma cutting table he built a few years ago too.

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Plasma Cutter On The Cheap Reviewed

April 15, 2024 by Al Williams 24 Comments

If you have a well-equipped shop, it isn’t unusual to have a welder. Stick welders have become a commodity and even some that use shield gas are cheap if you don’t count buying the bottle of gas. But plasma cutters are still a bit pricey. Can you get one from China for under $300? Yes. Do you want one that cheap? [Metal Massacre Fab Shop] answers that question in the video below.

First impressions count, and having plasma misspelled on the unit (plasme) isn’t promising. The instructions were unclear, and some of the fittings didn’t make him happy, so he replaced them with some he had on hand. He also added some pipe tape to stop any leaking.

The first test was a piece of quarter-inch steel at 35 amps. The machine itself is rated to 50 amps. Sparks ensued, and with a little boost in amperage, it made a fair-looking cut. At 50 amps, it was time to try a thicker workpiece. It made the cut, although it wasn’t beautiful. The leaking regulator and the fact that he can’t run the compressor simultaneously as the cutter didn’t help.

From the look of it, for light duty, this would be workable with a little practice and maybe some new fittings. Unsurprisingly, it probably isn’t as capable as a professional unit. Still could be very handy to have.

It is possible to convert a welder into a plasma cutter. A handheld unit like this probably won’t benefit from a Sharpie.

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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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Keep The Sparks Away With A Plasma Cutting Table

December 5, 2021 by Bryan Cockfield 8 Comments

For one-off projects or prototypes it’s not uncommon for us to make do with whatever workspace we have on hand. Using a deck railing as an impromptu sawhorse, for example, is one that might be familiar to anyone who owns a circular saw, but [Daniel] has a slightly different situation. He had been setting up metal workpieces on random chunks of brick in order to use his plasma cutter, but just like the home handyman who gets tired of nicking their deck with a saw, he decided to come up with a more permanent solution and built a custom plasma cutting table.

Plasma cutting has a tendency to throw up a lot of sparks, so most commercial offerings for plasma cutting tables include a water bath to catch all of the debris from the cutting process. [Daniel] builds his table over a metal tub to hold some water for this purpose. The table itself is built out of aluminum and designed to be built without welding even though most people with plasma cutters probably have welders as well. The frame is designed to be exceptionally strong and includes curved slats which add to the strength of the table. The table is also designed to be portable, so the curved slats stay in place when the table is moved.

While this might seem like an average metal table at first glance, the table is actually being designed with a homemade CNC machine in mind which [Daniel] is working on. The CNC plasma cutter needs a sturdy, flat surface and can’t be set up on bricks in the driveway, so this table suits both [Daniel]’s immediate needs to not shower himself in sparks every time he cuts something and also his future CNC machine’s need for a sturdy, flat workspace. We look forward to seeing that build being completed but in the meantime take a look at this motorized plasma cutter which has the beginnings of a CNC machine if in one direction only.

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Magnetic Motorized Plasma Cutter Track

December 29, 2020 by Danie Conradie 10 Comments

Affordable plasma cutters are becoming a popular step up from an angle grinder for cutting sheet metal in the home workshop, but cutting long straight lines can be laborious and less than accurate. [Workshop From Scratch] was faced with this problem, so he built a motorized magnetic track for his plasma cutter.

Thanks to a pair of repurposed electromagnetic door looks and adjustable base width, the track can be mounted on any piece of magnetic steel. The track itself consists of a pair of linear rods, with the torch mounts sliding along on linear bearings. A lead screw sits between the two linear rods, and is powered by an old cordless drill with the handle cut off. Its trigger switch was replaced by a speed controller and two-way switch for direction control, and a power supply took the place of the battery. The mounting bracket for the plasma torch is adjustable, allowing the edge of the steel to be cut at an angle if required.

While limit switches on the end of the track might be a preferable option to prevent sliding base to hit the ends of the tracks, the clutch in the electric drill should be good enough to prevent damage if the operator is distracted.

[Workshop From Scratch] is really living up to the name of his YouTube channel, having built many of the other tools used in the video himself. Just a few examples are the XY-table, hydraulic adjustable workbench and hydraulic shop crane. Continue reading “Magnetic Motorized Plasma Cutter Track” →