Hello, I'm trying to MIG weld some 1.5mm thick square tubing using argon/co2 mix, 0.8mm wire and a clarke 151TE welder. At power setting 4/6 it seems to make a nice weld and penetration seems ok when I weld on a flat bit of metal. When I try to join two pieces of the tube at right angles though there doesnt seem to be enough penetration. I've been trying to weld on setting 5/6 to get more penetration, but when I finish welding (on a flat bit or joining two piece at right angles), a big bubble sometimes rises up from the weld at the end where I stop welding. It seems to happen more when I move along slowly. I'm worried that there might be gas of some sort trapped in the weld even when it doesn't blow a bubble. What do you think is causing the bubbles? Thanks for any help! Dave.