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MIG? Yes, MIG!

Since I'm doing my own AF conversion, I do plan to do as much work as possible myself. What I would like is a cheap MIG that can be used to spot weld aluminum. That way I can get everything lined up, tack it all in place, and then take it to someone to TIG the whole thing up right. Any suggestions and/or experiences with a decent MIG unit that can do this?

Not on MIG for aluminum.
I have a Lincoln MIG unit I bought a couple of years ago. I tried a couple of times to set it up for aluminum and it did a crappy job. I needed to rent an argon bottle, change the liner, change the feed rolls, finally ended up buying a different torch with a short cable just so it would feed wire reliably. It did a crappy job. "tacks" were big 'ole globs or nothing at all.

Take a look at available TIG units these days. If I were going to do it again I'd not spend the $800 I did on the MIG unit and rolls and stuff and just spend the $1300 on a TIG unit.

You have a couple options but they are not going to be cheap unless you already have a mig machine that is spool gun compatible. Like KarlP said running the aluminum mig wire through a conventional mig sucks. the aluminum wire is so soft that it usually birds nests at the drive wheels at the machine unless it is a push/pull set up where there is a drive roller in the handle of the mig that pulls the wire while the drive rollers at the machine push the wire through the lead simultaniously. Again like KarlP said you'll have to change the liner so the aluminum wire does not get contaminated with the steel shavings from the original liner. i prefer to use a helium argon mix for aluminum mig and straight argon for tig. the best option is a spool gun that houses a small 1 lb. roll of aluminum mig wire with a self contained spool motor thus eliminating the need to run it through a conventional mig lead. the mig machine has to be spool gun compatible for this option. Depending on the size of the mig machine (115v or 220v) you'll want to preheat the frame with map gas or a torch because the the 115v won't have enough amperage to to give you a good strong tack. Aluminum requires much higher amperage to weld than steel. hope this helps and good luck!!
Horrnet

Thanks for the info gentlemen. Very informative.

A buddy of mine has a small portable MIG that I would call a spool gun. It carries the welding wire in the handle. It is very similar, if not the same, as this one: http://www.amazon.com/Mechines-Converte ... B004N51OR6 Would this work to tack everything in place?

It's worth a try.

If you can make a decent tack you can weld it out, though.

I have never welded aluminum plus it has been almost 15 years since I welded on a regular basis. Plus, I have heard that a MIG just won't do the job as well as a TIG as far a the structural integrity of the the pieces being joined. This is just what I have read as I have no experience with TIG machines at all.

TIG is by far the way to go for strength. The spool gun you showed should work ok for what you are looking to do but it might be worth spending some extra money and get a TIG to start out with. A TIG is not that hard to learn to use, Pretty will take practice but you can just go back over your ugly weld with the torch and smooth it back out. You will want to find a TIG with a pedal to adjust the amperage.

Also once you have the TIG you will find many uses for it. They will also do steel and stainless along with other things. Plus once you have the set up you will most likely make a bunch of new friends!

Good luck with the search.

If you have a AC/DC Arc (stick) welder you can get a tig adapter for around 200.00. My buddy just got this setup and it works quite well.

Does anyone have a recommendation for a good introduction to welding book? I've always wanted to learn, but I want to read up on it a bit before buying anything.

no book recommendation, but, for around $100 I took a 10 week class at a community college. Best money ever spent. Covered stick, mig and tig.

dfeckel wrote:Does anyone have a recommendation for a good introduction to welding book? I've always wanted to learn, but I want to read up on it a bit before buying anything.

Find someone with a welder and just try it. It's not that hard to learn. If you can get a stick welder to learn on it will be harder at first but you will probably have a quicker learning curve. Any one can mig but stick will give you a better idea of what you need to do to get a good weld.

Lots of good advice here, I took a course in college and it has served me well with my ac/dc Lincolin. Now if I just had a tig.....