THC turned off, cuts great

been having trouble with the voltage on the THC. Turned it off in fire control. Cuts great. What the hell?

Did you read and try the suggestions in your OTHER post on THC???

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I was in the same boat. I had no idea what I was doing wrong with all of the wiring. I did the same thing just to see what would happen, and low and behold, the TCH works perfect. There went about 9 months of lost production. But it’s working now so I guess there’s that.

Lets clarify that the THC is not what probes the metal and sets the pierce and cut heights. Those functions are part of the IHS(initial height sensing) system and they work with any table that has a powered Z axis.

The THC only has one job. That is to take a voltage reading at the start of a cut loop and move the Z axis up and down to keep that voltage within the specified range. It needs to get good voltage readings in order to function properly.

If you turn off the THC in Firecontrol, it is no longer looking for those voltage readings, so you don’t get the associated errors. The table will work fine with just the IHS system, as long as your steel is relatively flat and you don’t have any long cut loops.


i wonder if people are not dropping the torch holder down far enough and thc is getting a high reading to start with making bad cuts.

then if not low enough the ihs switch can keep lifting torch to a cut height.

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Having the same issue. Added the THC to the Pro and runs through all the Tests and Shows good to go.
I Run it in program, and it does the THC test, fires the torch, cuts for a bit and then stops. I can hit reset or continue, and it will do the same thing and cut for a bit and then stop. Pops up the Error page for Voltage. As soon as I stop using the THC control and shut it off, the Torch cuts Perfectly fine and I Just have to have my height spacer just right.

In the Error box, it mentioned Ground. I have it mounted to a solid Stell Undershelf that I added to the stand and Ground is good.

I do have a lap top swing side to side stand from Langmuir mounted to the table. I run a laptop. So, in the Error Box it said to UN-PLUG power to the laptop and or run some sort of a USB adapter for Filtering if I understood correctly. I have owned this unit since August of 2022. I am totally new to this CNC Plasma table stuff and the Software has been my struggle to this point to be able to use more often. I also had an unheated shop and didn’t want my water table to freeze. So, everything has been on Hold till yesterday. I finally decided to work through the issues. So yesterday was the First time using the Unit with the upgrade for THC. Runs the Test Flawless, but as soon as it gets part way into the actual cut is just stops and says Reset cut. I know it has to be something simple but makes me scratch my head. Love to get this table working so that I have some more confidence in use. Open to Suggestions or options.

What plasma cutter do you have?

Are you using Smart voltage or nominal voltage ?

can you post the first chuck of code from your program?

can you post a picture of how your torch in mounted?

Is the work clamp on the material?

what was the voltage on your passed test?

The sequence at the start of each cut loop is not a THC test. It is the IHS (initial height sensing) loop and it is not related to the THC. It will still probe the Torch down and set the Z height with the THC turned off. There should never be a need to use a spacer to set the torch height with a powered Z axis, even without a THC.

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I was able to figure it out.
I removed my Laptop off the Swivel Stand to the Unit that I bought as optional Acc. I put it on a Poly Saw Horse 2’ away and then Boom it worked. I must be getting interference some how in the electronics. THC works great and did a beautiful 1st go Cut out that looked perfectly matched for Cut Pressure, Heat Setting and Spead rate.

Can you add a picture of your setup and tell what type cutter and laptop you are using?

Others may benefit from your info when they have similar issues with similar equipment.