[TRC87]

Hello all,

I'm having a unique problem with my electrodes. I've searched forum after forum and I can't find anything. Before I describe the problem, I'll give you a rundown of the setup I am using:

Longevity LC-520D multifunction machine (TIG/Stick/Plasma cutter) hooked up to 220V
Adjustable pedal with max amperage set to 110 amps
3/32" electrode
#6 cup
Argon with regulator set to about 15 SCFH
DCEN

Now, the problem: when I try to start a puddle, the arc is fine for about 2-3 three seconds. Then there is a crackling sound and the arc becomes erratic. I'll let off the pedal and look at my electrode. The electrode will be glowing red hot and it will no longer have a sharp end. It'll be very round. At first, I thought the electrode just too close to the puddle and maybe I dipped it in. However, after sharpening the electrode 4-5 times and being VERY careful about my arc length, I am certain that the electrode was not dipped into the puddle. I'm getting very frustrated with this. I taught myself to MIG weld and I can lay down some gorgeous beads with great penetration, but I can't even begin to learn to TIG because of this.

After I got my machine, I did have to call the company and order a new pedal. The old pedal would only put out 2 or 90 amps, nothing in between. The new pedal seems to work fine, so I don't think that is the issue. I don't have a water trap attached to the Argon tank because the one I had kept leaking. Maybe the problem is moisture in the argon?

Hopefully, this isn't a machine issue. So far, Longevity has given me great customer service and I would hate to have to call them again because something else on my machine is broken. Also, I don't have another $500 or $1,000 to spend on a different machine... I've attached links to pictures of the electrode to give you guys an idea of what I am describing. Does anyone have any idea what I could be doing wrong or what could be wrong with my setup?

[Jay_M]

Might I ask what you have the A/C balance set to? I think you may find the culprit in that setting.

Sorry if O sound vague, I'm posting this from my phone.

Edit: After hitting submit, I realized "He never mentioned aluminum". Haha. I definitely had a brain fart. Anyway, might I now ask what material you're welding on?

[TRC87]

My machine is DC only, so no AC balance here. Today, I was trying to weld on some 1/8" flat stock that I was using to fabricate a motorcycle brake metal mount. After 45 minutes of ruining electrodes, I got fed up and just did it with my MIG.

[Jay_M]

Sorry about that. I don't know what I was thinking. Haha.

Do argon and air for the plasma come into the machine on seperate ports? Or the same port?

Have you leak tested all the hose connections, starting at the bottle?

I suspect gas, but there are people far more qualified than I around here and I'd be interested to hear what they have to say.

[blaz]

It looks as though you have the polarity reversed. I see no note of whether you are running electrode neg or electrode pos.

[rake]

Have you got the tig torch hooked to the negative or the positive terminal?

[blaz]

Also found this;

http://www.millerwelds.com/resources/te ... oting.html

Let us know what you find please.

[Mrkil]

There are 3
Times when I have seem this lately.
1 tig gun plugged in but machine was still set to stick
2 reverse polarity. Electrode +
3 someone in my both stood on my agron line.......

[AFSATCOM]

The only time I've seen an electrode turn black is when I forgot to turn on the gas. Not saying that's what you're doing but something may be screwing with gas flow, you got the wrong gas, bad gas or like I've done forgot to turn on the gas. When I forgot the gas it wasn't focused and quiet like it should be. The arc flared out alot and there was a hissing sound. Like gas flow hissing but louder.

I hook up my leads backwards the other day (been playing with stick too much). The only result was the electrode was balling up. I was trying to weld copper for the first time and thought there was something going on with the metal cause the arc was very erratic. For troubleshooting purposes I struck an arc on steal. I noticed cleaning action around the arc and that's when it dawned on me. The was no blackening of the tungsten when I did the steal I just saw it ball up and noticed the cleaning action.

Hope this helps

[TRC87]

Thanks for all the replies. I'll answer your questions in order.

Jay_M: The argon and air for plasma go into the same port. Unfortunately, it is a ribbed nipple, not a threaded port. I had to attach another ribbed nipple to my argon bottle just to be able to connect it. I haven't leak tested any connections yet. I didn't realize that weak argon flow could cause a burned electrode. I'll go through and leak test everything tomorrow.

blaz: Sorry about not listing the polarity. It is DCEN. On my machine, since it is DC only, this is the only way to hook it up. The connectors for the torch and ground clamp aren't reversible (at least, I don't THINK they are).

Mrkil: It looks like blaz's post with the Miller resource sheet and everyone else's response agree with yours. I'm guessing at this point that I have an argon leak somewhere.

I suppose I'll leak check all my connections and make sure there aren't any hose kinks tomorrow. I'll let everyone know what I find. In the mean time, if anyone can think of another cause, let me know! Thanks!

[AFSATCOM]

I forgot to mention that after a few times of forgetting the gas, I started hitting the switch on the torch then holding it up to my ear just to make sure I can hear the post flow and to purge the lines.

[KennethDante]

I don't know much about argon or shielding gas, but even if there is a leak, how bad can the leak possibly be in order to cause such a drastic breakdown of things. Doesn't sound reasonable unless its totally kinked line or it is disconnected. How's about checking your torch assembly/collet body deal. I've come across a few folks who have had them in backwards or wrong and messed up the flow of things. Just an idea!

[AFSATCOM]

I don't know much about argon or shielding gas, but even if there is a leak, how bad can the leak possibly be in order to cause such a drastic breakdown of things. Doesn't sound reasonable unless its totally kinked line or it is disconnected. How's about checking your torch assembly/collet body deal. I've come across a few folks who have had them in backwards or wrong and messed up the flow of things. Just an idea!

I could be wrong here but from what I've seen and heard, a leak in the line will pull O2 into the lines by a venturi effect. I haven't seen or heard of this doing something that bad but I could see the possibility especially if he's trying to keep the arc going even if it's not right. I did see picks of a torch where the guy managed to get the collet in backwards though. Dunno how he pulled it off but he did.

[Jay_M]

Thanks for all the replies. I'll answer your questions in order.

Jay_M: The argon and air for plasma go into the same port. Unfortunately, it is a ribbed nipple, not a threaded port. I had to attach another ribbed nipple to my argon bottle just to be able to connect it. I haven't leak tested any connections yet. I didn't realize that weak argon flow could cause a burned electrode. I'll go through and leak test everything tomorrow.

Are you running the proper drier and filter on the compressed air line when the plasma is hooked up? You may have a case of oil or moisture in the internal gas lines.

You mentioned a nipple connection, is this secured with a pipe clamp or similar?

Hope we can get you straightened out soon, I'd hate to be without my machine.

[TRC87]

Jay_M: I have actually never even played with the plasma cutter. I know, shame on me for only using the stick and TIG functions of the machine... Usually I'm good at finding reasons to use new tools, but I just haven't found anything good that needs plasma cutting yet. I do have a worm drive clamp securing the hose at the Argon bottle as well as the machine.

KennethDante and AFSATCOM: I just triple checked my torch. The whole assembly is in there properly.


I think maybe this weekend I need to get a new length of hose to connect the bottle to the machine. While I do that, I'll make sure I don't have the nipple on the bottle cross-threaded or otherwise improperly installed causing a leak. What kind of hose would you guys recommend for connecting the bottle to the nipple on the back of the machine? Right now I'm using some 1/4" ID fuel line. It's pretty hefty stuff and it can hold gas pressure upwards of 60 PSI, but maybe it isn't the best choice for this application.

[Otto Nobedder]

It sounds like an obstruction in the line, very close to (or in) the flowmeter.

The regulator before the flowmeter is set anywhere from 45-75 PSI, and allows pressure to build in the line, despite obstructions. This is why it welds fine for a few seconds... When the gas solenoid opens, it's releasing the pressure in the line to the torch at a good rate. Then the flow drops off.

What style flowmeter are you using? Is it the type with a dial, that looks like a small version of a pressure regulator? It will mislead you, because it IS a pressure regulator, and will always read 15, if you set it for 15, regardless of actual flow. It will give you a line full of gas at the set pressure, for a couple seconds of welding, then die off if there is a problem.

If you have the floating-ball style flowmeter, you should be able to activate the torch and watch the ball for several seconds, even if you have to arc to something behind your back, and look for a change in actual flow.

When we replace supply lines from flowmeter to welder at work, we use 3/8" nylon air-brake tubing and compression fittings. These hold up very well and don't "weep" argon like less rigid lines.

The description in your original post really suggests to me the problem is between the flowmeter and machine, close to the flowmeter, or in the flowmeter itself. That tungsten in the picture is exactly what happens if you weld for a second or two without gas.

I always recommend the floating-ball flowmeter, because it does read actual flow, regardless of conditions.

Steve S

[TRC87]

I do use a floating ball meter. I had a dial meter before on my MIG, but it was a piece of junk. Now I have identical flowmeters on my MIG and TIG. The one on the MIG works fantastic. Maybe there is something wrong with the one I have hooked up to the TIG. I'll take it off this weekend while I replace the line and rebuild it with a parts kit. Below is a link to the flowmeters I have:

http://www.usaweld.com/Welding-Flowmeter-p/12020-f.htm

Otto Nobedder, do you know where I can get a short length of the air-brake tubing you were talking about? Would AutoZone have it, or do I need to go to a specialty automotive shop?

[Otto Nobedder]

That's a good question... I've never bought any myself... What I use at home is always "salvage". I use it as water line in my camper (even hot water). If autozone doesn't have it (they probably do), find a truck shop nearby. A mechanic might just give you a six-foot length of drop from a roll-end.

Steve S

[Otto Nobedder]

Also, since you have this type flowmeter, I'd suggest you try my idea... Arc to some junk behind you and watch the ball... Does it fall after several seconds, despite the arc in progress? This will help diagnose.

Steve S

[TRC87]

Alright guys! The problem has been fixed. I basically took everyone's advice and assumed it was a problem with my shielding gas flow. I diagnosed it by starting at the bottle and working my way toward the torch. After inspecting the flowmeter and it's connection to the hose, everything was fine. I looked at every inch of the hose and found a large slit about a foot from my machine. It looks like someone may have dropped something heavy or sharp on it at some point... Since I'm the only person who works in my garage, I have to assume it was me. In any case, I replaced the whole hose and fired it up. I was laying down horrible beads in no time... Now I just need to practice until I can't see straight and maybe I'll be able to make a decent weld. Thanks for all the help!

[Otto Nobedder]

Good to hear you've sorted it out!

I'll have to file that one away for future reference... Perhaps the high-pressure flow that occurs when the solenoid opens was able to overcome the leak-rate for a second or two, then most of the gas at the set flow was leaving through the slit...

With it working right, time to turn and burn! Share some pics, when you're comfortable!

Steve S

[fisher]

I get a similar effect if I get the filler rod too close to the tungsten