Don't let your aluminum get too hot!
I was welding up a little aluminum project with my Powertig 250EX. My amps were at 110 and I was using pulse. It had several welds in a small area and so the aluminum got pretty hot. Pretty soon the aluminum started to collapse. Too much heat!
So if you are welding aluminum, stop and allow the whole thing to cool down a little bit before going on otherwise you will find yourself with a blob of aluminum!
Powertig 250EX
Powerplasma 50
Hobart Handler 210 with spoolgun
Cobra 2000 / Henrob O/A torch
Drill press / metal brake / 36 ton air hydraulic press
Franzinated modified Craftsman 33 compressor
Lots of other metal working tools