Not sure what you mean by bubble? Things to check: tungsten contamination, correct color code, check shielding gas, correct polarity?, oil or something on the metal/filler rod? Using correct filler rod? Also this sounds dumb but make sure it is steel...one time I was trying to weld a piece of stainless to some aluminum (no it doesnt work good
If there are sparks coming off the tungsten then the tungsten needs to be sharpened. If it looks like you are trying to arc weld then maybe the shielding gas needs to be increased. I think mine is at 10CFH usually. Try both and see if that helps.
Gas is on and it is set to a 10 sec post flow. Tungsten is sharp. Polarity is correct. I am pretty sure it is contamination but I am a novice at welding so I will let him chime in with more detailed info.
Sounds like not enough gas from what I understand. I recall the same thing happening to me whenever I would run out of gas, or have it too low of a setting. Turn it up and keep welding. It could be contamination of the weld surface or the tungsten. Check all those things everyone else has suggested too because TIG is real touchy in some situations.
Metal is durty, clean it off, dirty as in dirt or slag or anything other then bare metal. Also If your filler rod is not new it could have moisture or other contaminents in it and it wont stabalize the pool, what rod type are you using. Also I have found that if you get a weld that is really dirt or you have no choice but to weld on a dirty surface, use some 308 stainless rod.
Muriatic Acid (pool acid from Home Depot, it's hydrochloric acid - DON'T BREATHE THE FUMES) will remove the plating. Grinding it will not. Grinding removes enough to look like it has, but smears enough of the plating into the 'bare' metal to still screw you up. If your mouth tastes metallic, STOP !! You are welding plated metal.
BE DAMN CAREFUL with the acid. It will hurt you if you are not careful. Safety glasses are an exceptionally good idea, a face shield is even better.
Know that steel freshly rinsed off with H2O from an acid bath will rust amazingly fast. I use compressed air to dry it. Waiting for it to air dry will incur some surface rust. It's that fast.
Make sure your gas is good. Last 2 bottles of argon were bad. Both had contaminent's. They have to send it out to be analyzed, and are reluctant to admit it's contaminated. What have you changed, since the last time you used the machine? You know, when it welded OK.
Which welder are you using? Is this a liftarc or a High Freq Start Welder? If the High Freq isnt working that could be a cause, if you arent getting enough current that can do it, too. Has this welder worked well in the past?
It may be the high frequency setting. I can't tell which one is start and which one is continuous. Let me go get some pictures. There was some cutting oil when I notched it but usually wiping it off takes care of it and I don't have any problems. I'll go get some pictures and post them and maybe you guys can tell me what the heck all these darn switches are.
Oh yeah, it was the 70s2 fill rod or something like that.
Also, how do you turn off the pedal? I tried to change the output to the middle and to ON and it would start an arc (barely) and it just wouldn't go. It would barely stick the tungsten to the metal if I just left it on the metal.
Maybe you should take a class on welding. Some Community colleges have pretty good intro class. Or finding someone who could sit down and teach you. there is a lot more to TIG welding than mashing the pedal down.