I don't know if this is old info, but you can get some really nice Al beads out of a small mig machine with a few tweaks. No spool gun needed!

First, pure argon, no mix. Maybe someone knows why, or if a mix will work, but I couldn't get it to.

.035 wire. The .035 wire is stronger and will be less likely to bunch up in the machine. When setting the feeder tension, go as low as you can that the wire will still feed. It's better to let it spin on the wire when it gets stuck than make a little birds nest.

Tip drilled out to .0625 (1/16, the smallest drill I had). Aluminum expands more as it gets hot, and will clog up in a .035 tip. They didn't have any bigger that fit the machine at the welding store, so made my own.

Keep the line to the gun as straight as possible. Again, less likely to bunch. wound up zip tying the line to crates that were about the same height as the machine all the way to 4 or 5ft from the work.

CLEAN. Kind of duh, but aluminum likes to be cleaned. Sometimes even baking the part can help. Pre-heating can be helpful on thicker or stubborn pieces too.

That's about it, any more advice or info would be great, but it's already done everything I've wanted it to do. It's my friends machine, he welded up some holes in his intake manifold and made intercooler piping. I welded 3 IC's together. I'll try and get some pics if people want them. I prefer TIG, but this is cheap and works good enough.

 

Nylon liner helps too

 

No, it's not old for those who are just purchasing mig welding machines, I just purchased mine yesterday. I was looking for a different way then using a spool gun, thank's a lot for this! Cheers!