250pi inconsistent cutting arc?

[moespeeds]

I've got a 250pi multifunction. Today I was cutting holes in some 3/8" plate, and was having some issues. The arc seems to cut on and off as I'm cutting. I tried 30-40 amps, 70 PSI air, and different distances from the metal. In open air the arc fires and holds just fine, so I'm thinking a setup problem? I checked the ground, and changed the consumables with no improvement. What else could cause it? It cut just fine on some 14 ga plate I had, just seemed to have problems with the thick stuff.

Thanks,

Moe

[Gadget]

Try lowering your air pressure to 50-55 PSI. If that doesn't help I think you have a CNC switch on that unit, try turning that on. That should maintain an arc that might normally go out. If that doesn't help try connecting the pilot arc wire directly to the ground. Let us know if any of these suggestions help.

[KHK]

Check the center electrode on the torch. It is spring loaded and must move freely.

[LONGEVITY]

The problem can also be with the Air Compressor not putting out enough consistent pressure. We had this problem with one of our compressors at the test station and we replaced it. The arc would sputter on the old one.

Try turning down the pressure, if that does not work, please check the compressor.

[moespeeds]

The center electrode moves freely, I did check that. For air, I have 2 5HP industrial IR compressors running inline with 200 gal tanks each. For my paper recycling operation we have a micropul that requires a steady 130psi of dry air to run, and I'm pulling air off that source. I will try turning the PSI down, but airflow is one thing we can count out. Like I said, the arc runs fine on it's own or on thin material, seems to be the the thick stuff that causes the issue.