Standalone CNC Tube Cutter/Notcher Does It With Plasma

October 14, 2025 by Tyler August 11 Comments

Tubes! Not only is the internet a series of them, many projects in the physical world are, too. If you’re building anything from a bicycle to a race cart to and aeroplane, you might find yourself notching and welding metal tubes together. That notching part can be a real time-suck. [Jornt] from HOMEMADE MADNESS (it’s so mad you have to shout the channel name, apparently) thought so when he came up with this 3-axis CNC tube notcher.

If you haven’t worked with chrome-molly or other metal tubing, you may be forgiven for wondering what the big deal is, but it’s pretty simple: to get a solid weld, you need the tubes to meet. Round tubes don’t really want to do that, as a general rule. Imagine the simple case of a T-junction: the base of the T will only meet the crosspiece in a couple of discreet points. To get a solid joint, you have to cut the profile of the crosspiece from the end of the base. Easy enough for a single T, but for all the joins in all the angles of a space-frame? Yeah, some technological assistance would not go amiss.

Which is where [Jornt]’s project comes in. A cheap plasma cutter sits on one axis, to cut the tubes as they move under it. The second axis spins the tube, which is firmly gripped by urethane casters with a neat cam arrangement. The third axis slides the tube back and forth, allowing arbitarily long frame members to be cut, despite the very compact build of the actual machine. It also allows multiple frame members to be cut from a single long length of tubing, reducing setup time and speeding up the overall workflow. Continue reading “Standalone CNC Tube Cutter/Notcher Does It With Plasma” →

Skateboard Wheels Add Capabilities To Plasma Cutter

July 28, 2025 by Bryan Cockfield 4 Comments

Although firmly entrenched in the cultural zeitgeist now, the skateboard wasn’t always a staple of popular culture. It had a pretty rocky start as surfers jankily attached roller skating hardware to wooden planks searching for wave-riding experiences on land. From those rough beginnings it still took decades of innovation until Rodney Mullen adapted the ollie for flatground skating before the sport really took off. Skateboard hardware is quite elegant now too; the way leaning turns the board due to the shape of the trucks is immediately intuitive for even the most beginner riders, and bearing technology is so high-quality and inexpensive now that skateboard hardware is a go-to parts bin grab for plenty of other projects like this plasma cutter modification.

[The Fabrication Series]’s plasma cutter is mounted to a CNC machine, allowing for many complex cuts in much less time than it would take to do by hand. But cutting tubes is a more complicated endeavor for a machine like this. This is where the skateboard hardware comes in: by fabricating two custom pivoting arms each with two skateboard wheels that push down on a tube to hold it in place, the CNC machine can roll the tube along the table in a precise way as the plasma cutter works through it.

Of course, cutting a moving part is a little more complicated for the CNC machine than cutting a fixed piece of sheet metal, so [The Fabrication Series] walks us through a few ways of cutting pipe for various purposes, including miters and notches. The first step is to build a model of the pipes, in this case using Onshape, and then converting the 3D model of the pipes into a sheet metal model that the CNC machine can use. It does take a few cuts on the machine to fine-tune the cuts, but in no time the machine is effortlessly cutting complex shapes into the pipe. Don’t have a plasma cutter at all? You can always build your own from scratch.

Thanks to [JohnU] and [paulvdh] for the tip!

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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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