Help please

[Freebird01JM]

Hello everyone I used to be on the plasma pig list I didn't post much. I have since given up my business and just use my table for personal stuff now.

I have a DHC circa 2006 I believe with a HT1250 G3 series plasma cutter.

This thing used to cut really well and all of a sudden now I can get it to cut to save it's life.

I have all genuine HT consumables...yes I have dry air. I just replumbed my shop with steel lines and a 3/4 copper cooling manifold right after the compressor.

I'm trying to do some since cutting in 12ga but no matter what I do I am getting nozzle blow outs or it will cut fine for a bit then all of a sudden crap. I'm trying to use 40a fine cut unshielded consumables. Even with a new nozzle and electrode it's still doing it.

The height control has been not working well either. But even with it turned off I get terrible results. My ground clamp for the PC is on the plate itself and not attached to the grating...

I've tried running slow....Ive tried running fast...I've played with air pressure...cut height...and nothing is working...

[Freebird01JM]

Here are some pics of what I'm talking about

[weldguy]

I would more than 40 amps for 12g. Have you tried 65 amp consumables? Are you sure your air is clean and dry? I know you have new lines and a copper cooler but that doesn't mean your air is clean and dry. How do your consumables look? Is the hole in the nozzle still round? Any black staining inside the nozzle and around the electrode?

[Freebird01JM]

I've run this combo many times... Yes my air is dry. There is no black staining inside the nozzle... I'm thinking it may have been arcing when it was stalling when setting pierce height. I reset that stall height to .01 instead of .06 and that seemed to help ...I was down to 55ipm

[adbuch]

I've run this combo many times... Yes my air is dry. There is no black staining inside the nozzle... I'm thinking it may have been arcing when it was stalling when setting pierce height. I reset that stall height to .01 instead of .06 and that seemed to help ...I was down to 55ipm

From your photos, it looks like you're cut height is too high, and perhaps insufficient air pressure. For 12ga. mild steel using FineCut consumables, Hypertherm recommends 40 amps, 70 ipm, cut height = 0.080" for your HT1250. Hypertherm recommends 90 psi minimum air pressure at the entrance to the machine while air is flowing to the torch. If you have not already done so, I would recommend installation of an air pressure gauge directly at the entrance to the machine, and making sure your pressure is 90-100 psi while air is flowing (i.e. - the machine is cutting). I run 100psi to my Powermax 85 measured as just described.

Are you using 3.11 or have you upgraded to Design Edge? It may be helpful if you could post some screen shots from your Settings pages for Height Control and Machine Control so we can see what your actual settings are.

It is important to have a sufficient supply of clean, dry air. I personally use a refrigerated dryer just ahead of the plasma cutter to eliminate any residual moisture.

You say "I'm thinking it may have been arcing when it was stalling when setting pierce height." This indicates to me that for your Pierce Height Reference you have checked the box for "Stall on material to zero". There should not be any arcing between the shield and material, and the torch should not fire until it has retracted to the pierce height. What setting are you using for pierce height? My settings for my Powermax 85 are normally pierce height= 0.150" and cut height= 0.060". I cut 12 ga. per Hypertherm mechanized cut charts at 45 amps, 120 ipm using FineCut shielded consumables.

David

[adbuch]

The height control has been not working well either.

Please elaborate. Are you using 3.11 or Design Edge? If Design Edge, have you upgraded to Advanced Height Control?
Thanks,
David