Danl, I don't know what you are trying to weld or what it's doing, but I can help you out a little if you need it.
The first rule when welding aluminum is to have it clean clean clean. Grind down anything that needs it and if you have one, take a Tigerpaw disc and and smooth out the grind area very well. When that is done, take some acetone and cleans it up a little more.
Aluminum is very prone to falling out on you if it is thin material. Dont be afraid to start and stop to give the metal a chance to cool. It is very hard to tell if the metal is getting too hot until it falls out and completely screws everything up.
I am not a fan of Hobart, but they do make a few good machines. I would definitely stay away from the ones sold in the farm stores though. They used to be one of the better made machines and they still have one of the premier welding schools, but it is almost impossible to find any of their equipment being used in any type of industrial setting these days. If I remember right though, Miller bought them out.
Let me know if I can help you out in any way.
Tex
