Starting the arc on aluminum (TIG)

[LBHgti]

So I've had my TA185 for some time now, and it hasn't got a lot of use simply because I haven't needed to do much with aluminum, and MIG has been more practical for most of my steel projects. I have cut up about a million coupons out of aluminum to practice on, and I'm having some problems. Butt welds are no problem, arc starts nicely, wets out nicely and evenly on both pieces...and then I continue on with my bead.

Here's the problem....every time I try to make a lap joint or TEE joint, I always end up burning away the edge on the top piece of my lap joint, or the upright piece of my TEE joint (horizontal welds). If I focus the arc on the lower piece...nothing much happens...but as soon as I get near the top piece, it just burns away. Thickness of workpiece doesn't seem to make much difference, Although I haven't tried anything thicker than 3/16". I'm doing work on my makeshift welding table....a 3' x 2' piece of 1/4" steel set on top of my workbench. What am I missing here?

BTW...none of these welds are structural, and the only injury possible in the case of a failure is one on my foot from kicking the workpiece across the garage in frustration.

[Joe H]

Believe it or not, you are running a little cold. Turn up the amps a little, start arc on horizontal piece, get horizontal piece to puddle quickly right at the joint, quickly move the arc to the vertical piece and dab some filler in to join the two puddles. Once you get that far it's a cakewalk. You also may want to adjust your flowmeter for just a tiny bit more flow for a fillet weld.

[Pangea]

^ What he said. Also, that 1/4" table might be sucking the heat out of your part as fast as you apply it. Lay the coupon on some GTAW wire that is bent into a 'U', wide enough to support it.

eta, either that or leave it on the table and put a chunk of angle on the back side to even things out.

[LBHgti]

thanks, I'll give it a shot.