Hello, all,

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 a
1/8 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!

Jon