Tig question from a rookie

I'm new (as in never ever tigged) and after I replace the fan that I broke on my 250ex I want to tig the seams on an aluminum Battery box I will be bending up while waiting for the fan to arrive. The material will be .040 3000 series sheet what settings should I start with?
I will most likely use 2t or 4t on the torch sw.as it seems a bit less complicated then a foot pedal right now Can I fuse it or do I have to use filler rod? The good news is I have plenty of extra material to play with. I also intend to practice on sheet metal before commiting to aluminum. and pointers and ideas would be helpful
Ray

Ray,
I would always keep some filler close at hand for this, especially if you burn through, you will need some assistance.
Here's what I would do:

Set the AC freq about 100 or so. Set the Balance around 30%.
Set preflow for about 2 seconds for the smoothest start. Start amps about 10, upslope 2 seconds, Welding amps about 30. Down slope about 3, end amps about 15. Post flow for about 5 seconds.

3003 is supposed to be pretty hot crack resistant, so you might find luck in welding it autogenously (without filler rod.) If you wanted to try that, a very good joint configuration for autogenous welding is as pictured. Bend the ends of the weld seam together to give you some material that can melt back and fuse together. A joint configuration like I have pictured (shown for welding thin (.020") copper sheet) would work well, I'll bet. Travel speeds on a joint like this can also be very high.

If you do a more traditional joint using filler rod, 4043 would be a good choice. .040" is some pretty thin (challenging) material to learn on. I welded some .020" aluminum recently and although I can do it, it was pretty challenging, need a stable arc start and low-amp operation, which seems to be a lot about grounding, tungsten grind and cleanliness. To me .065" seems like a walk in the park. .040" is just a matter of practice. As the material gets thinner, finer hand manipulations of the torch and filler rod are necessary.

Taking the time to make a tight weld joint fit-up and getting it properly tack welded is also important; expect to spend time learning that as well. Hope this helps and best of luck!

Why not use your mig on that project, after all mig welders were invented to weld aluminum and 040 wall should be no problem for your mig.

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Originally Posted by geezer

Why not use your mig on that project, after all mig welders were invented to weld aluminum and 040 wall should be no problem for your mig.

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Geezer I was under the impression that Mig for aluminum was only for the thicker material. But then again I admit I don't know a damn thing. I'm sure someone will come on to either confirm or deny what you said.
I do have a spool gun for my mig and some .023 or.030 wire so I could play around with that also.

Quote:

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Originally Posted by Ram48

Geezer I was under the impression that Mig for aluminum was only for the thicker material. But then again I admit I don't know a damn thing. I'm sure someone will come on to either confirm or deny what you said.
I do have a spool gun for my mig and some .023 or.030 wire so I could play around with that also.

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YES you are correct .040 is way too thin, my mistake. I was thinking something around .125

Quote:

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Originally Posted by geezer

YES you are correct .040 is way too thin, my mistake. I was thinking something around .125

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Thanks "G" you saved me some time a aggravation by letting me know mig could not be uses on.040

Quote:

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Originally Posted by Ram48

I'm new (as in never ever tigged) and after I replace the fan that I broke on my 250ex I want to tig the seams on an aluminum Battery box I will be bending up while waiting for the fan to arrive. The material will be .040 3000 series sheet what settings should I start with?
I will most likely use 2t or 4t on the torch sw.as it seems a bit less complicated then a foot pedal right now Can I fuse it or do I have to use filler rod? The good news is I have plenty of extra material to play with. I also intend to practice on sheet metal before commiting to aluminum. and pointers and ideas would be helpful
Ray

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I would use some filler autogenious welding with alum tends to crack out