Yesterday your plasma cutter was cutting sweet. Today it cuts like absolute shit. It hasn't fallen off the bench, nobody's been inside it, and as far as you know nothing's changed. So what the bloody hell happened?
I don't start by blaming the plasma cutter. I start by blaming myself. What did I change? Because nine times out of ten I've buggered with something since the last time I used it. Changed the consumables. Moved to a different power point. Knocked the torch off the bench. Done something without even thinking about it. That's where I'd start looking first.
Over the years I've learnt that plasma cutters don't usually just wake up one morning and decide to stop working. Most of the time there's a reason, and if you think back through what you've changed since the last job, you'll normally find it a lot quicker than you will by pulling the machine to bits.
The next thing I'd be asking myself is, did I knock the torch? Not drop it off the bench or run over it with the ute. Just knock it. Put it down a bit hard on the steel bench or bang it against the job while you're working.
I've done that plenty of times myself. Especially when the torch is still hot. You only have to tap it a bit harder than you meant to and you can crack the ceramic. Sometimes they break clean in half and that's obvious. Other times they'll crack internally and you can't see a bloody thing from the outside.
If you think you've knocked the torch, pull the ceramic cup off and actually have a good look at it. Don't just glance at it and say, "Yeah, she'll be right." Hold it up under a decent workshop light and have a proper look around the inside. Hairline cracks can be bloody hard to see, especially if they're on the inside.
If you still can't see anything but you've got a suspicion that's what's happened, I'd probably replace it anyway. They're cheap as chips, and it's a lot easier than chasing your tail for the next couple of hours trying to work out why the plasma cutter suddenly started cutting like rubbish.
Just remember that not all plasma torches are built the same. On some torches the ceramic cup simply directs the airflow, while others have an internal ceramic insulator hidden inside the torch body. If you've got one of those, pull the consumables out and shine a light down inside the torch. If that internal ceramic has cracked, it'll cause exactly the same sort of problems.
If you're not sure which torch you've actually got, have a look at my Torch Identification Guide before ordering any parts. It'll save you buying the wrong ceramics or consumables.
The next thing I'd be thinking is, did I have the torch apart yesterday? Because it's amazing how many problems start after you've been buggering around with the consumables.
I've caught myself out with this more than once. I thought I'd done everything up properly, but I obviously hadn't. A few cuts later the electrode had vibrated loose and the plasma cutter started cutting like absolute crap. Straight away you're thinking something's wrong with the machine, but it wasn't. It was my fault.
While you've got the torch apart, don't just whip the old consumables out and throw the new ones in. Actually have a look at everything. Is there a bit of slag stuck in there? Has something not seated properly? Is the electrode actually done up tight? Half the time the fault's sitting right there in front of you if you slow down for a minute instead of rushing to get back to cutting.
One thing I've learnt over the years is that plasma cutters don't usually break all at once. They normally give you little hints first. The cut gets a bit rougher. It starts a bit harder. You notice a bit more dross than normal. Most of the time the machine's trying to tell you something. You've just got to stop and listen before you start spending money.
The next thing I'd be thinking is, did I move the earth lead? It sounds stupid, but how many times do you move it because it's in the bloody way? I know I do. You're halfway through a job, shift it to get another cut in, then five minutes later you're wondering why the plasma cutter's turned to shit.
Don't assume that because the clamp's still hanging onto the steel it's doing its job. I've had them clipped onto rusty steel, painted steel and all sorts of rubbish over the years. The clamp hasn't fallen off, so you don't even think about it. Meanwhile the plasma cutter's trying to push all that current back through a lousy connection.
Before I'd start pulling the plasma cutter apart, I'd unclip the earth lead, find a nice clean bit of steel as close to the cut as I could get it and have another go. If it suddenly starts cutting properly again, you've probably just found the culprit.
If that doesn't change anything, then I'd start looking a bit closer at the earth clamp itself. They have a pretty hard life. They get thrown on the floor, dragged around the workshop and slammed onto steel all day long. Every now and then you'll find the cable's half broken where it bolts onto the clamp, or the copper strap inside has had enough. It still looks like an earth clamp, but it isn't doing much of a job anymore.
Then I'd be looking at the compressor. Not because compressors suddenly wear out overnight, but because they do something overnight that catches a lot of people out. They cool down. When they cool down they create condensation, and all that water ends up sitting in the bottom of the tank.
If you haven't cracked the drain valve for a while, don't be surprised if there's a fair bit of water sitting in there. Then you fire the compressor up the next morning, it stirs all that moisture up and starts pushing it down the airline. Next thing you know the plasma cutter's cutting like rubbish and you're wondering what changed since yesterday.
It only takes a few seconds to drain a compressor. I do it every now and then without even thinking about it. It's just one of those little workshop jobs that saves a whole lot of head scratching later on.
While you're there, have a listen to the compressor as well. Is it running flat out the whole time? Is it struggling to keep up? If the plasma cutter was working fine yesterday and today the compressor never seems to stop running, you've probably found another clue.
The next thing I'd be looking at is the plasma cutter itself. Not pulling it to bits, just having a decent look at it. Has one of the knobs been knocked? Has the amperage somehow been wound back? It sounds stupid, but I've seen it happen. You throw the plasma cutter in the back of the ute, drag it out at the next job, and somewhere along the line one of the controls has been bumped.
Then have a look at the vents. Plasma cutters are like vacuum cleaners. They suck air through the machine to keep everything cool, but they don't just suck in air. They suck in grinding dust, steel filings and all the other crap that's floating around a workshop as well.
Every now and then I blow mine out with the airline. You'd be amazed how much rubbish comes flying out of it. Leave it long enough and all that conductive metal dust starts building up around the electronics. Electricity and steel dust aren't exactly good mates. Best case, the machine starts playing up. Worst case, you end up shorting something out that didn't need to be shorted.
It's only a five-minute job, and it's a lot cheaper than buying a new plasma cutter.
By this stage, I'd be resisting the temptation to start buying parts. It's easy to convince yourself the plasma cutter's half-rooted, but most of the time it isn't. Work through the simple stuff first. That's nearly always where the problem is.
Having said that, consumables are different. They're designed to wear out. If yours are looking pretty second-hand, or you've had them in there for months, there's nothing wrong with fitting a fresh set while you're fault-finding. At least then you know you're working with good consumables instead of wondering if they're part of the problem.
If you do need a new set, I've got PT31, SG51, AG60 and P80 consumables here on the site. Just make sure you're buying the ones that suit your torch.
One thing I've learnt over the years is that plasma cutters don't normally fail all at once. They usually give you little hints first. The cut gets a bit rougher. It starts a bit harder. You notice a bit more dross than normal. Most of the time the machine's trying to tell you something. You've just got to stop, think about what changed, and work through it one step at a time.
If you've worked through everything in this article and the plasma cutter is still cutting like rubbish, don't panic. The next step depends on exactly what it's doing.
Hopefully you've found the problem before you've spent any money. One thing I've learnt over the years is that plasma cutters don't just wake up one morning and decide to cut like shit. Something changed. The trick is working out what it was before you start throwing money at the problem.
