I'm still learning the fine art of TIG welding, but making progress. I'm doing the first real project, a table for a 24 x 36" surface plate. I'm using 2.5" OD steel pipe, "electric resistance welded, drawn over mandrel" and steel angle. The pipe looks almost like it was chromed, but did have a hint of rust on it, but I have no clue as to alloy. The angle I'm using is hot rolled, but other than that, no clue to alloy, either. I'm having a HELL of a time keeping the electrode clean. It gets something, I assume steel contamination all over it, heavy up to the cup, and light all the way up to the collet, in just a few minutes of welding.
Once it is contaminated, it starts popping sometimes almost like an oxy-acetylene flame, really loud popping about 4 times a second. This popping, if I allow it to continue, causes my Lincoln Square Wave 300 welder to shut down. At first I thought the popping was a problem in the welder, and it was shutting down due to some fault in the current control. But, after studying the manual and what was happening, I'm coming to the conclusion that the popping is driving the current control nuts, and it causes the excessive open-circuit protection interlock to trip. Another nasty thing it does is the arc starts climbing up the electrode until the arc is flowing from somewhere way up inside the cup, instead of off the tip of the electrode!
I can only keep the electrode clean for 15 seconds or so, then stuff starts spattering onto the electrode, I think. Sometimes I touch the electrode to the metal, but that contamination burns off after a few seconds, it seems.
Has anyone had this sort of trouble before? I'm using DC Electrode negative, HF on start, and about 250 A max on a1/8 inch EWP electrode. (I have a box of Thorium electrodes around here, but I can't find them right now.) I'm running about 15 CFH or pure Argon, and have tried both size 8 and size 5 cups.
I thought my torch had gas lenses in it, but I now have discovered that is does not have them. I'll have to get some next time I'm at the welding store.
And, that may be soon, as I seem to be going through Argon at a frightening rate! I had no idea the Argon was going to be the most expensive consumable in this TIG welding stuff! I got half off for my first fill, but they tell me it will be about $40 for the next fill of an 80 Cu Ft tank!
Thanks much in advance for any comments!