Just bought used Lincoln precision Tig 185 with water cooler, this is my first attempt at welding 1/4" aluminum after endless hours of research on the internet mostly here and at weldingtipsandtricks.com. Im using a water cooled torch, #8 cup, 3/32 2% thoriated tungsten, gas lens, 3/32 4043 filler rod, 18 cfm argon gas. I have penetration turned all the way up, pulse off and post flow at about 20 and the amps are at max 185. I used stainless steel brush to clean joints,then sprayed with aluminum cleaner I also beveled all joints that I was able to. Its 1/4" C channel on 3/16 plate. I mig and Tig at work but only mild steel and stainless. This is my first Welder for my personal use, I really want to get good at aluminum. The inside corners are very hard to get to. I would really appreciate any suggestions