I am a self taught welder. I have tig welded for over 10 years, mainly steel stainless and silicon bronze. I would consider myself a very good welder. I have recently started working a lot with aluminum and am getting frustrated with what I feel are non satisfactory welds (mainly the presents of porosity).

The thing is that since I am self taught I don't know exactly what you should be able to achieve.

I weld mainly 1/4" 6061/6063 with 4043 filler rod. I have a brand new Dynasty 350.

An example of difficulty I am having is the following:

I am making a frame out of 2.5" 6063 square tubing with .25" wall. I miter the tube and bevel the ends to receive weld so I can grind flush. I use walter grinding discs made for aluminum. After I grind I sand off any burrs, clean with lacquer thinner and then wire brush with dedicated stainless brush. I clamp the frame down to my table and begin to weld. When I first puddle the joint and add a bit of filler rod, if I continue to hold the arc over the puddle it just bubbles. In fact any time I strike an arc and form a weld puddle on Aluminum it will just sit there and bubble. Is this normal? I don't see how it is possible to get a porosity free weld if my puddle is bubbling. I am running straight argon at about 20-25. I am welding at about 250 amps with 1/8" zirconiated tungsten with a gas lens. I have messed with all the setting to no avail.

The other 'is this normal' question I have is: with the afore mentioned settings, how long should my tungsten tip last? I grind them to a truncated point with the flat spot being at least 1/16" in diameter and I only get about 6" of weld before the tip start to deform (starts melting and splitting at tip).

Please help.

Thank you.