I used a TIG welder on aluminum for the first time today to repair some deep curb rash gouges on the wheels of the RX-8. I have TIG welded steel before, but I was a little hesitant to do aluminum since it has a reputation for being significantly more difficult. I found this series of how-to videos on YouTube by Miller Electric. They did a good job prepping me for what to expect and a lot of it is good habits for TIG welding in general. The only advice I have to offer from my whole hour of experience is that the besides using AC instead of DC, different tungsten and different filler, the concept works the same as TIG welding steel. The only difference is that aluminum has significantly different heat transfer characteristics. Aluminum is able to suck heat away from your torch location a lot faster than steel does, especially on something big like a wheel. It may take a lot longer to start the initial puddle and it will be a lot trickier to maintain it. That’s why these videos emphasize puddle control so much. Just think of it as driving a car with no traction control besides your throttle pedal inputs. You have to be very ginger and precise with the throttle adapt it the situation you see with your eyes, just like the TIG pedal. It takes almost the same kind of hand-eye-foot coordination, so most car guys should have a leg up on a random beginner off the street.
Part 1: Setting up your welding position.
Part 2: Calibrating your torch and filler rod movement with a mock weld.
Part 3: Puddle control practice using only the torch without any filler rod.
Part 4: Moving the puddle and adding filler rod.
Source: Miller Welders on YouTube