I've recently bought a Power Tig 200 DX to use specifically for aluminum. It's amazing how it seems like aluminum learning is 2 steps forward to one back. I spent 3 weeks training myself each night and finally became comfortable training on flat peices and now edge welding. Learned to tack every 6" to minimise distortion. Welded out a fairly large project then ran into a wall with filet welds. I read thru this forum learning the tricks to run a bead on the edge and now it's time to search for the filet. Ive welded tig, mig n stick on carbon steel and never imagined aluminum being so hard. But that's why I bought this machine. It's an impressive piece of equipment. Welding on edge seemed best at 100 Hz. What do you guys set frequency at for 1/8" aluminum filet welds....lower frequency to hit both sides or higher frequency to pinpoint the arc?