THC Raising on cuts, pulling my hair out

Did a little digging but have not found anything that has worked so far.

Firecontrol 20.5 THC 1.09. Hypertherm 45xp new consumables. Dry air.

THC is raising during cuts. Even on generated 8" test cuts.

The cut pierces and I get around 108V live then dumps down to 85-95V live before the cut ends. The UP traffic light comes on as well the torch moves up. My nominal is set at 110V which has worked well for me the last 3 months.

I have checked for isolation from the enclosure to the table as well as pin 4 to the table via tech supports recommendation. I am isolated. I have also installed an adapter at my laptop plug to remove the ground prong as well as uplugged the computer all together for testing purposes. I have also moved the plasma machine as far away as I can and tried my best to separate all cords from on another.

This issue arose suddenly after removing my plasma cutter to cut some sheets in half by hand (I have done this many times).

Anyone have any recommendations?

Dumped my nominal voltage down to 70v, and the THC is working now. What would cause this? I have ran at 110v locked in for months.

Also, now when I pause my cut between rapids (end of cut moving to start of new cut) I get the “Cutting Voltage Not Detected By LS-THC” which never used to happen. I assume that is not normal. Is there some sort of short I should be looking for?

@langmuir-daniel @langmuir-mike

Are you seeing “live” (non-zero) voltage when the torch is not firing?

What you are seeing with those errors between Pauses may be an issue in FireControl 20.5. Had you updated recently?

I am seeing 0 voltage when the torch is not firing. Between “rapids” or while the torch moves down just before pierce.

My time line went as follows.

  1. torch started to move up on its own, (no pausing errors at this point, did lots of trouble shooting and would of noticed) so I updated firmware on THC and Firecontrol even though I believe I was on the latest versions. I do not believe I noticed a pausing error after this, but can’t recall for certain.

  2. Tried live voltage, it dictated my voltage should be around 65-75v for proper height (which is odd that now that is what it wants to see VS the 110 it has been happy with the last while, same thickness of plate)

  3. Resumed cutting my project, but had a tip up so paused to clear and got the “Cutting Voltage Not Detected By LS-THC” error message.

Still having my torch raise way up, even with smart voltage enabled. I have a USB isolater on the way but am wondering what my next move will be if that doesn’t solve the problem @langmuirsystems

have you done the L1 isolator mod? basically desoldering the l1 inductor from the board.

Also, i think there is a bug when you pause in 20.5. Same thing happens to me when i upgraded to 20.5. I’ve seem others post the same as well.

As far as I knew, my batch already had the mod done out of the factory. When I first started using the machine I was having grounding issues and I think I looked into that mod back then to confirm it was done. But I will certainly double check because at this point im willing to do anything to get it to work.

Working with the machine right now trying to get all my orders done for christmas and still fighting the thing. It will cut on smart voltage OK for 75% of the cuts, but 25% of the time it raises itself up to 3/8" or more.

I guess this is an improvement over it raising all the way up like it was doing when I was not using smart voltage as I can salvage half the cuts that it occurs on (where before when it raised it just completely fucked the cut since it raised all the way to the top.)

I am willing to run any tests or measure whatever I need to with a multi meter to determine where the problem is. My concern is that the isolator will get here and not fix the issue (since I have never needed an isolator before and it worked fine without one for 4 months.) and I will be shit out of luck because everyone will be on holidays. I am also located in Canada so getting replacement stuff is not just a few weeks away.

Issue still exists with the 20.6 update and new THC update. However I am now seeing .9v live when torch is not firing. @langmuirsystems

Also seeing 27-40v live with the VIM unplugged from the enclosure

@ktice Take an air hose and blow off the Z-axis screw and lead nut, clean with alcohol and blow it off again. I fought this same issue for months and the root cause seemed to be the grime bridging continuity from the IHS switch to the lead screw.

I will give that a try again, I just feel like the fact that the live voltage has changed so drastically indicates some sort of electrical issue.

Also double check that you are not using a laptop cord with a grounding plug. Those were the two things that caused me many bad days of cutting and a lot of headaches

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