I get asked this one quite a bit. Blokes buy a plasma cutter, use it for a while, then they start looking at YouTube videos of CNC plasma tables and think, “I wonder if I can bolt my plasma cutter onto one of those?”
The answer is... maybe.
Some machines are pretty close already. Others will have you stuffing around for weeks trying to make them work, and by the time you've finished, you could've nearly bought a plasma cutter that was built for CNC in the first place.
The first mistake most people make is thinking that because their plasma cutter cuts really well by hand, it'll automatically work well on a CNC table. It doesn't work like that.
A plasma cutter that cuts nicely while you're standing there holding the torch can be a complete pain in the arse once a computer takes over. That's where you find out there's a lot more to it than just bolting a straight torch onto the front of the machine and hoping for the best.
I've owned plenty of Chinese plasma cutters over the years, and most of them have been bloody good machines for the money. But there's a big difference between a good hand-held plasma cutter and a good CNC plasma cutter. That's what this article's about.
Before you even start thinking about CNC tables, work out what torch is on the machine now.
A lot of the bigger Chinese plasma cutters run a P80 torch or something very close to it. Some of the smaller machines run PT31-style torches. Some run other torch types again.
That matters because the torch affects what consumables you use, what sort of straight CNC torch might fit, and whether you're even starting with the right sort of setup.
If you're not sure what torch you've got, don't guess off the amp rating on the front of the machine. Start with the plasma torch identification guide first.
And if your machine already runs a P80-style setup, the hand torch and straight CNC torch will often use the same front-end consumables. If you need them, the P80 tips, electrodes and cups are here.
This is where people get caught.
You might be able to swap the handheld torch for a straight CNC-style torch and lead. On a lot of these Chinese machines, especially the ones running a P80-style torch, that part can be fairly straightforward if the connections match.
But that doesn't automatically mean the plasma cutter is now a proper CNC machine.
Changing the torch is only one part of the job. The machine still has to be able to fire from the CNC table, stop when the table tells it to stop, and behave itself while a computer is trying to control the whole lot.
If you're specifically looking at swapping a hand torch for a straight torch, I covered that in more detail here: can you swap a handheld plasma torch for a CNC torch.
This post is more about the bigger question: will your actual plasma cutter work properly on a CNC table?
One thing a lot of blokes don't even think about is that once you bolt your plasma cutter onto a CNC table, you've now got a computer trying to run the whole bloody thing.
Now you've got two bits of gear that have got to get along with each other. Sometimes they do. Sometimes they fight like cat and dog.
I've seen blokes spend hours chasing their tail because the CNC table keeps doing weird shit. It'll miss cuts, stop halfway through, or the computer starts playing up. They reckon the CNC table's got a fault, when half the time it's the plasma cutter chucking out electrical interference every time it fires.
I've even had it happen filming YouTube videos. I used to film with my phone, and if I put the phone within about a foot of the plasma torch it'd just go bloody loopy. The screen would start flashing, it'd do all sorts of weird crap, and sometimes it'd just shut itself down. Move the phone away and it was sweet again. That's electrical interference.
That's why you'll hear people talking about HF start and blowback pilot arc machines.
HF machines use a high-frequency spark to start the arc. They cut steel just fine, but they can also throw out enough electrical rubbish to upset the computer that's trying to run your CNC table. Can you make them work? Yep. Plenty of blokes have. But there's usually a fair bit more stuffing around before everything starts behaving itself.
Personally, if I was buying a plasma cutter with CNC in the back of my mind, I'd buy a blowback pilot arc machine every time. They generally create a lot less electrical interference, and that's one less headache you've got to deal with.
The other thing is the price. Years ago, buying a CNC-compatible plasma cutter meant spending a fair bit more money. That's not really the case anymore.
I've actually got two almost identical plasma cutters sitting here. One's a normal hand-cutting machine, and the other one is the CNC-compatible version. They're basically the same bloody machine. The only real difference is one already has the CNC connections built into it.
From memory there was only about a hundred bucks difference between them.
So if you're buying a new plasma cutter today and you reckon there's even a small chance you'll build a CNC table one day, I'd spend the extra hundred bucks now and buy the CNC-compatible version. It'll save you a bloody lot of stuffing around later, and you'll probably end up with the machine you wanted in the first place instead of trying to convert the wrong one.
This is another thing a lot of blokes don't think about until it's too late.
A proper CNC-compatible plasma cutter doesn't just have less electrical interference. It also comes with the CNC control plugs already built into the back of the machine.
That means the CNC table can tell the plasma cutter when to fire, when to stop, and do everything it's supposed to do without you having to start pulling the machine apart.
Can you make a normal hand-cutting machine do it? Yep. Plenty of blokes have.
But now you're into extra wiring, relays, trigger circuits and a whole lot of mucking around trying to make everything talk to each other. If that's your thing, knock yourself out. I'd rather spend my time cutting steel than chasing electrical gremlins around the workshop.
For the small difference in price between a standard machine and a CNC-compatible one these days, I'd buy the CNC-ready version every single time.
Even if you don't build a CNC table for another year or two, at least when you finally decide to do it, the machine's already set up and waiting instead of becoming another project before you can even start your project.
This is another one that catches a lot of blokes out.
When you're cutting by hand, you naturally stop every now and then. You move the steel around, have a look at the cut, grab another bit of steel or have a quick drink. Your compressor gets a chance to catch up.
A CNC table doesn't do any of that.
If you've told it to cut a two-metre shape, it'll keep going until it's finished. If your compressor starts running out of air halfway through, the CNC table doesn't know or care. It just keeps moving while the cut slowly turns to shit.
That's why a compressor that's fine for hand cutting isn't always good enough for CNC work. The longer the cuts get, the more obvious it becomes if your compressor can't keep up with the airflow the plasma cutter needs.
I've talked about this in my other articles as well. Most of the time it isn't actually the plasma cutter causing the problem. It's air pressure, airflow, worn consumables or simply expecting the machine to do something it was never designed to do.
If you're already fighting rough cuts or going through consumables too quickly, have a read of Plasma Cutter Cutting Like Shit? Here's What I'd Check First and Plasma Cutter Turns to Shit on Thick Steel? Here's Why before blaming the plasma cutter itself.
If you're thinking about building or buying a CNC plasma table, this is what I'd be looking at first.
If you're not sure what torch is on your machine, start with the Torch Identification Guide. It'll save you a lot of guessing.
And if you're thinking about swapping to a straight CNC torch, read Can You Swap a Handheld Plasma Torch for a CNC Torch? first. It'll explain what actually has to match before you spend your money.
If you're buying a new plasma cutter today and you've even got half an idea that one day you might build a CNC table, I'd spend the extra money and buy the CNC-compatible version right from the start.
They really aren't that much dearer anymore, and by the time you've mucked around trying to modify a standard hand-cutting machine, you'll probably wish you'd bought the CNC-ready one in the first place.
Can you convert a standard plasma cutter? Yep. Plenty of blokes have done it.
But if you can avoid all the extra wiring, relays, trigger circuits and general stuffing around, why wouldn't you?
Sometimes spending another hundred bucks at the start saves you weeks of mucking around later.
That's probably the biggest bit of advice I can give you after owning a heap of these Chinese plasma cutters over the years.
Buy the machine that suits where you want to end up, not just what you're doing today.
You'll thank yourself later.
And if you're already chewing through tips or wondering why your plasma cutter isn't performing like it should, start with Burning Through Tips on a 70–110 Amp Plasma Cutter. It'll answer a lot of the questions I get asked every week.
