Could use some help with thc

I just got around to installing the thc upgrade to my original crossfire that I had purchased a while back when they were on sale. I am using the Hypertherm 45xp with fine consumables. I am set up using the raw voltage feed back option. I currently use sheetcam with the correct driver for LS-THC.

The first time I tried cutting a part the torch went to the proper position dropped and raised to proper height and pierced the metal and stopped with a reason that torch moved before voltage was sensed. I followed the guide it directed to and results are as follow.

  1. Resting voltage 0V, No voltage detected when dry fired.
  2. Measured voltage at banana plugs while cutting a line. 80+ Volts
  3. Measured voltage at end of PV out wire going to main box. appox 1.2V
  4. Measured voltage at white and grey wire on white board. 1.2V
  5. Measured voltage at A1 to GND on THC chip. No voltage detected.
    I am seeing where other people have had this issue and it was a faulty THC module.
    Not Sure what to try next? Thanks for any help!

what is the time for your pierce delay and your plunge rate?

.5 but tried all different settings in the override option.

plunge rate was factory setting.

are these both green in firecontrol? Also, how do you have the torch on/off cable and THC cables hooked up?


yes all green. I just removed control box from frame also. I will retest straight cut voltages at a1 and ground in a few.

That plunge rate should be changed to at least 50 IPM.

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At first i had the exact same problem except i have a Cut 45 instead of the hypertherm. Found that the connectors on the front of the machine were mislabeled in the manual so i had it connected to the wrong port. since you are not using the same plasma cutter but are having the exact same issue it would lead me to believe there is a wiring/connection issue as was the case for me.

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Interesting, How are you able to get your torch to fire when the ports were swapped?

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It had never fired. It was brand new with THC. It only fired manually when i squeezed the hand trigger. That’s when i knew i had 2 problems. It was a frustrating process getting it to fire for the first time compounded by my first cuts were on thin sheet aluminum, the machine not labeled and the manual labeled backward. I learned that using THC on thin aluminum is a recipe for disaster. I am hoping the fine cut nozzles will help reduce the heat affected area and stop the bowing but it so far it seems to be best practice to drag the tip to maintain critical dimensions.
If you have guidance, I’d love to hear how you do with Tin. Especially with smaller details like holes less than 0.31"dia, but maybe in a direct message so as not to clutter this thread with unrelated issues.
Maybe ill start a thread if they let me and we can discuss it there.

I can say that aluminum is probably one of the most fickle things to cut with plasma.

At least with hypertherm fine cuts have no cut charts because they don’t want you cutting aluminum with fine cuts.

Depending on how critical you need it as center Pierce and then drill is probably the best way to do if it needs to be perfect.

If it doesn’t need to be absolutely perfect depending on what cam software you’re using some proper lead and lead outs and approaches on the circle are going to help the geometry quite a bit.

If you start another thread and define the scenario you want to go over I’ll definitely take a look at it and I’m sure a bunch of the other guys can too, especially if it’s sheetcam.

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Like this…

Some of these ‘center punches’ are for M2 holes…


Update : I did a straight line cut no thc on an got approx 4.5 volts on grey and white wires. Took control box off frame, still not registering voltage. Not sure whats happening. I dont think i have a wiring issue with the voltages I am seeing.

how is the thc wired from cutter to control box?

Raw voltage from hypertherm into divider box with banana terminals. Then out to crossfire control box.

And you’re using the PV output on the VIM box, correct?

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Yes, PV port is being used.

Raw voltage installation manual hypertherm 45 XP

If you haven’t seen this manual I would thumb through it .

Red to work clamp (positive)

Back to torch (negative)

Is your polarity correct and are you using these terminals on your 45 XP?

Plasma machines are a
constant current electrode negative machine.

Yes, that is the directions I used to wire it up.

I would love to know how you did that center pierce. Im using fusion 360 to draw and to post.