THC not maintaing torch height

I have just recently installed a THC and an xl expansion kit for my crossfire. I have been trying to cut out a pretty intricate pattern and on the last part of the cut the torch just continuiously slowly increases in height till it is no longer cutting. It has really been frustrating. any ideas what is going on? I am using a hypertherm 45xp with machine torch and the plug and play langmuir systems cord.

Ok after a little more observation it is actually slowly raising up every time didnt notice on the smaller cuts.

Running smart voltage or writing in your own?

Have you run thc test?

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do you have enough slack in the torch cable so it’s not pulling up on the z axis on the far ends of the table?

I have run the thc test several times and am not using smart voltage as i t says it is for material 1/4in or larger. I am pretty sure it has all the slack it needs but will double check it when I get home.

its 14 gauge and over not 1/4 but I’ve using smart voltage on 16 gauge since I’ve had the pro for over 2 years now…

what gauge material are you cutting?

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16 gauge aluminium. If my voltage is set too low it would just keep raising to try and lower it correct. The THC test had the voltage at about 165v, while the voltage is set at 113v.

try using smart voltage then you’ll see what the average voltage your cutting at then you can set that on you’re own if you need to.

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If voltage was set to low it would hit the plate or cut closer.

What about electrical interference?

Is torch holder low enough so it isn’t tripping ihs.

I think the holder is flush with the bittom of the z axis carriage.

Probably not your problem. Is torch hitting material before green ihs light comes on?

How is your consumables?

Consumables are brand new, the torch touches the material before the torch ignites.

Is your USB cable touching the table legs?

Are you running a laptop?

How close is plasma cutter to the table?

Well I did attach the usb cable with a plastic c clamp I am using a laptop, the plasma cutter is right next to the table as the cable is not very long. Ugh i just need to take a pic.

I know I f my USB swings over and touches table. Crazy things can happen.

Is your laptop plugged into charger or running on battery?

Plugged in

Do you use a ground isolator?

Nope. It is an extison cord from across the room though.

Try running on a battery or get a plug adapter that doesn’t use the ground. It could be electrical interference.


If your table and your computer are running on an outlet serviced by the same breaker box they are sharing the same ground which seems to cause interference issues.

The alternative is to run on battery power, provide a separate ground rod for your table, break of your ground pin on your computer plug or use an adapter as @Phillipw suggested.

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