Tig welding tips, questions, equipment, applications, instructions, techniques, tig welding machines, troubleshooting tig welding process
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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.
Nick
KennethDante
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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!
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KennethDante wrote: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.
Nick
Jay_M
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TRC87 wrote: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
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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.
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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
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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?
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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
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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
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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!
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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
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I get a similar effect if I get the filler rod too close to the tungsten
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