Lots of problems in all these photos, but in general the amps are too low for the cold aluminum. I'd have set peak amps to about 130 amps on those 1/8" pieces. Black sooty contamination in earlier photos looks like poor/no gas coverage. 1st weld photo shows insufficient cleaning setting. Any chance those first coupons were anodized aluminum? Are you running that machine on 120 or 240? You'll probably need 240 for any decent results on aluminum.
I'm no expert, in fact I'm a total noob at TIG and welding aluminum. But I was making decent aluminum welds within the first couple inches of my first try at both. I don't get why everyone thinks this is so difficult. I did have a fair amount of experience with an OA torch on steels before that though. To me, TIG technique seems almost just like welding with a gas torch. The right settings, preparation, and material are key. A foot pedal is mandatory, I think, for a beginner.
The last photo is best but still a ****** weld (no offense). Way too cold at the start. No penetration and little fusion with the base. Rod technique looks promising though once you get the heat figured out. Cleaning setting looks a bit too much but not that far off.
It didn't start working till near the end once the metal got warmed up. Aluminum ***** a lot of heat when it's cold. Gotta pump up the amps and get it hot much quicker, then ease off on the pedal / move faster as it progresses. No point continuing with the bead if you don't get a good puddle going at the start.
One other point--vision. You've really got to have a good sharp view of the puddle area. Maintaining the correct puddle in aluminum requires constant adjustment and if you can't see it clearly you can't adjust. You need a helmet with adjustable shade to get the best contrast. Since I'm an old fart with poor vision, I had to put a cheater lens in my helmet to get a sharp view. And I've got to get my face right down in there close to the work.
^^^^^Read what Gerald posted^^^^^
TIG was not that hard for me, maybe because for 3 years
(about 30 years ago) I worked in a factory O/A brazing copper and brass connections on A/C, Heating and drink machine coils.
Watch the puddle and use the pedal, like Gerald said, until you get better at it.
I don't think it has so much to do with the type of aluminum that you are using. I have TIG welded everything from new 6061, 6063, 6351, cast aluminum crankcases, timing chain covers, aluminum screen door frames and even aluminum cook pots with decent results. The aluminum that you get at the "big box" stores is not some "alien" type of aluminum as some have noted. I have used aluminum angle and sheet aluminum from the "big box" stores with good success.
Aluminum must be clean, don't use the same wire brush for your aluminum as you do for steel..get a dedicated stainless wire brush for cleaning the aluminum and use it only for that purpose.
I am by no means a pro welder but I do a little bit of aluminum TIG, 2-3 times a month..... some of my aluminum welding projects....
