Random arc signal lost

I have a hypertherm powermax 65. I'm using a 7i96 with two thcad boards. 1 for ohmic and the other for torch height control. I have a problem that randomly happens when I'm running a program. When it goes to pierce it won't even spark but it will immediately give me a "valid arc lost" error and pause the program. I can try to resume the program and it might work or it might do it 4 more times before it works. The strange this is that I can hit "pulse torch" and it will fire the torch just fine. I was just wondering if anyone has any idea why it might be doing this? Again, it doesn't even flash an arc, it just starts the airflow from the torch.

Are you using a machine Arc OK signal or a synthetic signal?

I’ve actually seen this same thing. I’m using an actual Arc-OK from the machine (mode 1). I attributed it to using Ohmic2 vs Ohmic3, but I know CBEAR is on Ohmic3.

Machine arc ok

thefabricator03 wrote: Are you using a machine Arc OK signal or a synthetic signal?

I helped CBEAR set up his table, he’s also using the arc-ok input (mode 1), and is on v.169. I posted his setup files (for a different issue that we solved)
Here

Hopefully they help, but being as I’ve seen this too, I wonder if there’s an underlying issue?

Are you using Auto Volts or using Cut Volts from the material. If the latter then you need to ensure that the Arc Voltage shown in the GUI is the measured arc voltage.

phillc54 wrote: Are you using Auto Volts or using Cut Volts from the material. If the latter then you need to ensure that the Arc Voltage shown in the GUI is the measured arc voltage.

I had him switch over to auto volts.

Edit: I should add that maybe this is what made it go away for me, not sure I’ve seen it since I used auto volts

So it is still an issue with Auto Volts?

Yeah, I've used both. It does it on both as well.

You may need to break out Halscope and plot the Arc Voltage And Arc Ok.
Normally if you get a lost arc error then it has seen the arc ok and then it has lost it. It may be a noise issue. Have you done some probe testing to confirm the Z axis is at the correct height.