THC not working during cut

I’ve got a crossfire pro with THC and I’m not sure what’s going on.

The z axis drops to locate the material as usual and goes to pierce height. It pierces and drops to cut height but during the cut the torch is not moving up or down. I’m cutting thin aluminum and the tip of the torch keeps touching the material as it warps during the cut, which causes the cut to stop. Watching fire control during the cut the THC Control window shows no activity, it’s not controlling the torch during the cut.

Bout to take the plasma apart and check the wires inside. It’s a hard wired miller spectrum 625 x-treme.

Any ideas?

THC wont activate unless 1.) the program has THC H1 and H0 activation codes and 2.) The actual torch speed is within 85% of program speed. Consider checking these two conditions.

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Thanks. I haven’t changed any setting but did notice that will the most recent update to fusion360 the ‘G code’ window seemed to be different.

How do I check if the H1 and H0 codes are activated?

Alright. Got it working. Not exactly sure what the issue was but went back into fusion. Edited my tool and this field was blank and it’s a new field as far as I can tell in fusion. It now includes cut power and pierce power and psi. So I populated the field, which I believe I had already done before, and it ran fine.

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In FireControl, scroll through the program at the bottom and look for H1 and H0 codes. You should see them at the beginning and end of every cut loop.

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I’m pretty sure this has to do with something new in Fusion… It happened again.
I wasn’t looking close at the program this time because I caught it late and the cut was about done but I did see H1 popping up.

So it was doing it again. There are H1 and H0 codes throughout, at the beginning and end of every cut loop.
Not sure what is going on.

Is the THC connected in Firecontrol? The green light at the top of the screen for the THC connection, is that on? If its not getting voltage and the THC is active, it should be throwing an error and stopping the program.

To be clear, the IHS system that probes the metal and sets the pierce and cut heights is not connected to the THC. Those are separate systems and the IHS can work without the THC connected.

Yeah it’s connected. green light on. I got it working… same file same everything. HOWEVER, it seems like it might be the electrode. Seems to start working if I change the electrode… but if I do just a straight cut programed through fire control, no THC with the same electrode it works just fine. But I am just burning through these electrodes if I swap them out every time this happens.

there was a period where the THC live voltage was running really low, like 40v when it’s usually around 80-90. Maybe it was the ground but I can’t confirm. I cut and reattached the ground wire to the ground clamp recently. Unsure if it’s related but live voltage is back up to 80-90.

How many pierces and what cut time are you getting out of a set of consumables? There are some things that a necessary to get good life out of consumables.

When I was having intermittent low voltage readings it’s because my laptop was plugged in

Hard to say but yesterday I cut this and my electrode was done by the end. Had to swap it out this morning. .125 thick cold rolled running at 45amps and started at 75ipm but bumped it up to 120% of that during the cutting. Kept bugging out and I couldn’t get it to run the cut.

The THC was not working during these cuts. It would plunge but not adjust on the fly. So many issues that the last cut I had to program manually as an 8 inch straight cut through firecontrol. The torch fired right up and made the cut no problem. But with the same electrode it won’t run through the program. Plunges, fires for the pierce, drops down to the work piece and cuts out.

If that is all you cut there is something wrong with your setup… what kind of air dryer do you have. Enough moisture can destroy a electrode almost instantly.


Long story short, no dryer, just moisture filters. Main compressor crapped out last week so I’m running on a small one and have to pause the program between holes on long cuts like these to allow the compressor to refill. Very very very very annoying.

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Got ya. little air and moisture could be part of your problem. So thc has worked in the past?? Money you save on consumables will pay for a little air drying upgrade… I know money don’t grow on trees but you know.

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Yeah. The price of these electrodes is crazy. Been too busy to get moving on the compressor but I’ll make sure to get a dryer. I know I probably shouldn’t run my machine maxed out at 45amps if I want the consumables to last longer but I have it dialed to give near perfect cuts with very very little cleanup when it comes off the table.

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At least a bead dryer would help. Depending on where you live how hard you have to tackle the air thing. Friend a auto body shop in your area to see what they do… I would also tackle why thc isn’t working right. What else have you changed since it was working?

The miller spectrum 625 x-treme plasma cutter is only a 40 amp unit and has a 50% duty and takes clean dry moisture free air.

So low air, now air dryer, maxing it out on amps and ipm you are going to have trouble even if the THC works.

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A new plasma is in the future. This guys around 10 years old now but has been pretty good for what I do so far.

I’d like to add that I cut some parts this morning and THC was working. I can’t find a rhyme or reason as to why it works or doesn’t.