Tried my hand at MIG welding aluminum today. Got some 0.035 5356 wire, a clean new tip and borrowed a small tank of argon from a friend. I had no feed problems at all - guess I don't need the spool gun. But it's really tricky. Started trying to run some beads on a piece of 1/8" 6011 plate - won't be posting any pics of that! It's really hard to control the heat, and aluminum conducts heat so well that you can have a cold wel at the start of your pass and blow a hole through the end of the pass all while moving the same speed. Anyway, I finally decided to try on some actual joints, and found that having more material in the vicinity made it much easier - more thermal mass.