TIG noob = Tungsten goob! take a look!

[hooda]

So last nite, I was about ready to pull my hair out. I was trying to put spot welds on my tailgate back in, and every time i got a puddle started, it would jump back up the tungsten and form a big goober on the end.Like this.

In order to accomplish 15 or so spot welds, I had to re-sharpen about 10 times. Lucky I had 4 pieces of tungsten available. After I turned the amps up to about 120, I was able to pedal a puddle into the center of the spot, and back off a little to get this result.

Any ideas why I was getting this problem? I can see that I need to resolve this issue or doing panels will be a pain forever. Thanks!

[dirtyfarmer]

The auto companies use a lot of "coated" steel for rust resistance. There could be zinc or something similar on your panel. It does that (jumps to the tungsten) when you try to weld. Welding on plated bolts will do this also.

[geezer]

Wrong polarity or pure tungsten or both.

[Wookie]

put torch over place to be spot welded set amps high stomp pedal quickly make sure you are cleaning the base metal well

[jsclark4500]

To me it looks like wrong polarity, torch to close to work, wrong tungsten, or not enough heat setting. If these are right you should be able to burn through any coatings without trouble. Also, start at the edge of the hole and work in to the center in a circular movement. This will concentrate the heat longer in the puddle and allow the bad stuff to come to the surface and burn off.

[hooda]

The latest 2 posts seem to make the most sense to me. The polarity WAS correct. But looking back, I think that my main problem was that I was really pussyfooting around on the amperage, trying NOT to burn thru. The result was the opposite I would park over the center of the spot, and the heat would actually burn the edges of the top layer and chase it away from the center. then I would have this big nasty looking messs to contend with, the only advantage being that I had burnt away some of the crap that was interfering with the weld from the start. THAT is when the tungsten would goob. I'd have a red spot getting brighter and bigger, then the center of that spot would just "jump" onto the tungsten. I grew up brazing on applications such as this, and even with the trial and error factor being what it was, it was far better than fighting the warpage and paint burnoff that oxyacetylene would have created. Thanks for the pointers.

[Wrenchtamer]

I'm not sure what the conditions are in your shop, but I have had occaision where I was doing some thin sheet metal and the wind would gust. When this happens, It will blow your shielding away and burn right through instantly with thin sheet. The stuff on the tungsten is definitely contamination from the base metal. Make sure you clean the base metal up good and wipe it down with sometihng like acetone. Make sure you WIPE the surface and dont spray it. If you like your eyebrows where they are that is.

[jakeru]

Any moisture on your work piece is bad news. If you have rust, you probably have some moisture in there unless you have pre-heated it well somehow. H2O will boil and if stuck in a cavity, cause a metal "eruption". Galvanized (zinc) coating (or anything other substance with low vaporizing temperature... tin? maybe lead, etc) is also bad, it boils and offgasses metal vapor (which at best consenses into oxidized soot particles). Possible eruption risk if it is stuck in a porous cavity of the metal as well, which can before pressurized and when released, "spits".

Basically, TIG works best and cleanly, only when starting with clean, bare metals, ideally also with clean backsides on full penetration joints. Thin sheetmetal is in the full penetration category so backside cleanliness can be significant.

Now you can TIG weld on dirty stuff, just don't be surprised if your tungsten gets "goobed". Have a few freshly ground ones on hand to swap out. Definitely don't use a gas lens when doing it, unless, you want that screen inside there sacrificed to the welding gods. (covered in spatter and ruined.) Grinding a little but off a $.80-$2.50 or so 7" long stick of tungsten isn't too expensive, but ruining a gas lens collet body at a replacement cost of $5-$10/ea, can get a little painful, especially welding on some cheap, dirty project. So if you are welding dirty, definitely consider setting the gas lens collet body (with the easily spatter damaged screen) aside and just use a regular collet body setup.

Pre-heating rusty stuff with a cheap-o air-propane torch to evaporate H2O and burn/evaporate oils out of the porous rusty spots, may help a great deal reducing "eruptive action" when TIG welding.

[worntorn]

I'm not sure what the conditions are in your shop, but I have had occaision where I was doing some thin sheet metal and the wind would gust. When this happens, It will blow your shielding away and burn right through instantly with thin sheet. The stuff on the tungsten is definitely contamination from the base metal. Make sure you clean the base metal up good and wipe it down with sometihng like acetone. Make sure you WIPE the surface and dont spray it. If you like your eyebrows where they are that is.

I overlooked a very simple problem when I started in tig welding. I just couldn't figure out why the shielding was so poor on my torch.
The cooling fan on the welding unit should not be directed at your workpiece! If the welding unit happens to be in close proximity to your work table and is at roughly the same height, either move it or put up some kind of shield (without obstructing machine cooling)to stop the breeze from blowing the argon away.

Glen

[hooda]

Well put, Jake (and others). I spend most of my time on the net researching welding lately, and you seem to have a knack for putting it into words better than most. I was on Jody's site watching the latest in TIG of magnesium and he said to hold a tight arc, and something to the effect of the mag nothaving the affinity to want to "jump" onto the tungsten, which leads me to believe that other metals will have that affinity. I couldn't do a preheat to burn out the contaminants because I was trying to preserve the paint on the tailgate, not deal with warpage. So it all makes sense now. Thanks!