The best place to ask would be on a stock car racing forum where they are discussing how to make roll cages.

That would be one of those "bet your life" welds. I hope you are an experienced welder, because that is one of those applications where a failed weld or poor fitup or design can mean death. I weld OK, but I would turn down that job in a split second. That is just my humble opinion, your mileage may vary.

Kurt

I second that.
the little mig won't penetrate like a buzz box/stick will.
I wouldn't compromise in that case where your neck is on the line.

I have both a little mig and a buzz box...use the mig for tacking during fabrication and decorative stuff, but when it comes to serious hold, you want penetration, not build-up...it's important.

I would not trust the weld. It may look OK but the penetration is not deep enough as mentioned by modre. You could run some samples for bend tests. I would not use it.

My mig is a medium sized 175A 220V model. I would trust this weldER with this job, just not me the weldOR! In the right hands I think it would be no problem. I only have one right hand though :).

I've made several medium duty hitches and stuff for my small tractors, and never had a weld break. But, I dont really know how good they are since I havent done enough destructive testing to prove that my welds are as strong as the base metal. People on some other forums think I'm kind of unsafe with some of my projects and things, but I'm really kind of a safety nut in reality :).

Kurt

Thanks for the info. Where would I find a stock car racing forum. I have known of fellow racers that have used a mig for welding. Racing is not professional or anything more for sport.

Do a Google search under "I don't believe you and I'll do it my way as soon as I find someone who agrees with me"

you may have to refine your search with "experience means little"

then right click on "Goober"

Mig welding for critical case welds is something that requires a bit of experience. All edges should be chamfered and if this is a heavy wall tubing the joints should be preheated. Wire brush after the part is hot and be sure your machine has enough amperage to make a full penetration weld. Practice on some scrap tubing (cut apart the welds to inspect for full penetration) If your welding machine does not acheive full penetration do not use it for this application. Also check with your local welding supply to see what welding wire is recommended for Moly Tubing (You are using Moly Tubing for the roll cage tubing right?) A lot of racing folks will only use TIG for safety cage welding, that way they know their lives are protected by 100% penetration welds. Good Luck

Wow. That's an ambitious project for someone new to welding.

If it were me, I'd take a welding class at a local community college, and follow that up with a special projects class. The instructors should be able to guide you through all the pitfalls.

I took about 72 hours of welding class this past summer; we did flat and fillet welds with stick, mig, flux, tig. Welding tubing/pipe is a whole nother level, it seems, and I'd want someone to teach me that rather than learn the expensive way. Especially for something like a roll cage that you might have to weld in very awkward positions.

There's also the matter of cutting and bending the tubing properly, making the right joints, selecting the right welding method and filler... pre-heat and post-weld heat treatment to minimize heat affected zone weakness... a lot more to welding than just laying down a bead... After I took the summer course, I have a lot of respect for those who weld for a living.

Oh boy! finially somewhere I got alot of experience under my belt! Do NOT use the 110 volt box for your cage! as others above me have said you must get pentrention. No 2 ways about it. I found which 220 buzzbox I use to build my demolition derby cars made a difference whether the welds broke or not, I find if I use my dad's old centry buzzer and I mean buzzer built in 1937, the welds do not break, if I used a newer aluminum wound welder the welds would break maybe 25 % of the time . you gotta just gotta weld not lay beads. of course I use 6011 rod 1/8 diam and build it up if needed thicker rod tends to blow holes in the frame and that is a no no . all promotors are different some glance in not knowing what to look for some really drill and check welds You wouldnt bungee jump with truck tiedown straps would ya? a bar breaking and going the wrong direction can hurt maim and kill at 20 mph. I've hit at up to 50 mph and been hit too .... I might tackweld a cage in using the 110 then weld it in with the 220 stick I've seen welds that were beautiful in some cars but ripped at the weld itself not beside the weld..believe me ripped welds are sharp..