Plasma Problems

[performance]

The one thing we can't see is if the arc is transferring. Check your readout on the unit when you start your cut. See if amps drop in the display when you squeeze the trigger for the pilot arc, then see if it ramps up when you start to cut. Also you should notice a brighter flash in the arc when the arc transfers. It is possible you are trying to cut with the pilot arc only.

[Slartybartfa]

Mark, that's sort of the problem now. I can get a nice blue-white flame in mid-air. As I bring it into the work, very slowly, the moment the side of the flame contacts the metal, it goes out. No time to see if it's cutting. It isn't behaving the way it was earlier. It's no longer cutting weakly, it's simply going out. And though I haven't ever used a plasma torch myself, I've watched Jody and others' videos and I know what it should look like. The plasma flame is hotter than the surface of the sun and should go through 1/8" steel like a knife through warm butter. And it should make a clean cut, not a slaggy one, and the arc shouldn't go out.

[acourtjester]

Lets look at something different you say the PP256 is new have you done anythig with the unit then try plasma.
Will it stick weld, Tig AC/DC weld.

[Slartybartfa]

First thing I checked out was TIG (DCEN only). It did fine. Made a nice arc and I was able to draw a bead on mild steel. Then I tried the plasma torch and ran into difficulties, so haven't tried stick yet.
But what's bothering me is that, first I got some cutting action. Very weak and would barely go through 1/8" steel, and made a mess of the cut and the tip. Now it's not even doing that. Something has changed.

[performance]

Adjust your air pressure down bit by bit and see if it will resolve the going out. Also when it does go out keep your trigger held and touch the metal and lift up quickly. Do you see a spark or an arc establish?

[Slartybartfa]

Do you mean actually touch the tip to the work? I thought there should be a HF arc that should jump that gap. When you talk of the pilot arc, is that the blue flame I'm seeing when I squeeze the trigger in mid air? If so, then when I bring it in to the metal, it's evidently not transferring to the work.

I'll do as you request this afternoon.

[performance]

yes touch it to the metal. Yes, that is the pilot arc, which on your torch is Hf generated.

[SeanMurphy265]

One thing I have noticed; if I run too much air pressure all the air leaks out the dryer, and very little air comes out of the torch. When I have the proper air pressure more air comes out of the torch. I would adjust the air pressure coming out of your air compressor, and not the adjustment on the plasma cutter. The other day I ran into the exact same problem, and it was because my air pressure was too high and going out of the water valve on the dryer. It would not arc properly because there was not enough air coming through the machine. If you hook your air line up the plasma cutter and it sounds like all your air is leaking out the pressure is too high.

[zoama]

One thing I have noticed; if I run too much air pressure all the air leaks out the dryer, and very little air comes out of the torch. When I have the proper air pressure more air comes out of the torch. I would adjust the air pressure coming out of your air compressor, and not the adjustment on the plasma cutter. The other day I ran into the exact same problem, and it was because my air pressure was too high and going out of the water valve on the dryer. It would not arc properly because there was not enough air coming through the machine. If you hook your air line up the plasma cutter and it sounds like all your air is leaking out the pressure is too high.

Sounds like you've got a bad seal on the check valve. I've used 60psi for everything so far (pp256 and pp60) I just set the amperage and go.
That's 60psi running... about 68psi static.

[Rambozo]

Something isn't right for sure, unless you have some crazy high pressure air system. Those standard regulator/dryer units are rated for up to 250psi input. Nothing should be leaking out.

[Slartybartfa]

Just got home from my day job. Reassembled everything, didn't change the settings at all, except for dialing the Amperage to max (65 indicated) and Success!



Set the pressure to 60 and 80 but didn't notice any difference in the way it cut.
Held the standoff on the edge of the work, angled the torch out away from the side and squeezed the trigger. A very small, bright white flame shot forth and went through the metal like it wasn't even there. No splashback, nothing like before.
Don't know what changed, but that confirms that the cutter really does work. Now I need to make some guides so I can cut against a straight edge.

Thanks for everyone's input. Sure wish I could say exactly what the cause of my problems was. Could it be the new welding cart fixed it?

[SeanMurphy265]

It looks like your running too hot. You want to cut the metal and not melt it away. You probably could cut that material around 30 amps. I think 50psi is what I run.

[Slartybartfa]

Thanks, I think you're right. Went through a piece of 3/8" angle at the same setting and realized I probably could have dialed it back a lot. Having no frame of reference yet, I need to experiment and see what gives the best cut.

And re: your earlier comment about pressure, first thing I did when I put the parts together was to chase down all the air/argon leaks. Got all the connections sealed with teflon tape now and no air leaks. The water purge valve on the bottom of the water separator bowl was troublesome, so I took off the spring and now it seals perfectly. The spring was too stiff and was holding it open. And one thing about argon: once it's gone, it are gone!

[performance]

It could have simply been the work clamp cable is loose in the dinse connector or there is some oxidation on the metal that was preventing a good connection of the work clamp.

[Slartybartfa]

Something simple, anyway. I was afraid it was the HF circuit not transferring the pilot to the work. That doesn't seem to be the case. However, I tried dialing back the power to see how low I could go. And lighting the arc just off the edge of the work, I can' go below 50A or the arc blows out just as it did yesterday. But when I squeeze the trigger with the tip over metal, even just the bare edge of the work, with the amperage set to 50, 40 and 30A the arc lights and I can cut. But below 30A and it just "pops" and the arc blows out. I'm wondering if the "points" gap inside might be set wrong. I understand about 0.030" is about right for this machine.

So I think part of my problem earlier was that I didn't have the amperage dialed up high enough to light the arc reliably.

And sure 'nuff, dialing the power back resulted in a much cleaner cut, less slag, etc.