I've got some heatsinks that are .050" thick. The heatsink fins are about .200" long and .050 thick, but the flat oppsite sides are where I'm welding on.
I can lay down decent beads on a single piece. The arc is nice and stable, and as long as I don't dwell to long, I don't get too much sag or any burn through.
However, when I try to do a T joint with two of them, the arc tends to wander between the flat portions of the horizontal and vertical pieces. I can't seem to get the arc to focus on the joint.
The two pieces have been cleaned with a virgin stainless steel brush and wiped down with acetone. I've even tried it without the acetone with no real observable difference.
I'm running at about 80Hz, 30% DCEP, and 70A max current with a 3/32" pure tungsten electrode and a #5 cup.
Any advice would be appreciated.