This was done with a Millermatic 140 + Spoolmate and it's the exception to what I can usually produce- still practicing as much as my pocketbook will tolerate. Aluminum is quite expensive to "play" with but I'd rather ruin a practice piece than a project.

The pieces joined are 3/4" square (1/16"wall) and a piece of flat bar of the same thickness. I am defnitely always pushing the gun, turned the argon down, and experimenting with pre-heating the thicker materials. The thin stuff is still a pain in the a$$