a little help here...

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a couple friends and i were arguing about the alloy of a beer can. anybody know?  next is iwas asked to weld a roll cage into a spec miata, and start getting my tig stuff out. he said that a tig or stick weld was not recommended, only mig welds. that doesnt make any sense, i thought a cage was to be strong enough to take a crash and keep the driver alive. if you tig a motorbike frame together for strength, why would'nt you tig a cage together. i told the man to wait, that i would ask around on that one. i dont want to mig weld a cage together for liability reasons. not that i don't trust my welds, but i trust a tig weld over any other. any help on this one pleasenothing fancy, just a few hot glue guns for metalwww.sicfabrications.com
Reply:He don't know welding very well...do he?City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:No roll cage at all is better than one that's been tigged  ..... Just joking.If you're using standard mild steel tubing, don't worry about it.
Reply:As long as you have adequate penetration, either mig or tig will be fine. It's the filler alloy and dilution from the base metal that will determine the strength of the weld. When calculating the necessary size and strength of a weld, the welding process is not even considered. Now keep in mind that each process has its strengths and weakness. Such as mig might be better for long runs of welds on thicker material, while TIG may be better for smaller diameter tubing or thin material. Trying to use mig where a tig should be used may produce poor welds due to defects, and vice versa.Trying to say that one process is always stronger than another is like saying that everything in the world should be welded with a Sub-Arc, just because it penetrates deep and is fast. Just don't make sense.Arguing with a Welding Engineer is like wrestling with a pig... after a while you realize the pig likes it
Reply:If he wants a cage in a Miata he must have some plan to race it. If that's the case it will be governed by somebodies rules, have him show you the rules. It wouldn't be uncommon for it to be a case where he doesn't have the rules but was told that by someone.With that said, I have the rules from the major drag racing santioning bodies and they state MIG is ok for MS but Moly gets TIG only, both can be TIG however. Surely he wants Moly, why would anyone want that big ugly MS ?Anything worth doing is worth doing RIGHT
Reply:olddad is correct-2007 NHRA rulebook states in Section 16, subsection 4:11All cage structures must be designed in an attempt to protect the driver from any angle, 360 degrees. All 4130 chromoly tube welding must be done by approved TIG heliarc process; mild steel tube welding must be approved MIG mire feed or TIG heliarc process.  Welding must be free of slag or porosity.  Any grinding of welds prohibited.Other useful info-Cars without frame must use 6" square 1/8" thick steel plates on top and bottom of floor, securely bolted together with at least (4) 3/8" bolts, or top plate welded to rocker sill.All materials must be 1-3/4" O.D. x .118" mild steel or .083" 4130 chromoly tubing except the rear legs of a 4-point, which may be 1-1/4" x .118" mild steel or 1-1/4" x .065" 4130 chromoly tubing.The NHRA rulebook also has some criteria for how the bars of the roll cage need to be spaced in relation to the driver, but I dont know if you would need that.  What is he putting the cage in for?  As in, what sanctioning body would it have to pass inspection for?
Reply:Just out of curiosity, why would NHRA say that welds need to be free from porosity and slag. I think we can all understand the porosity part, but if only MIG and TIG are allowed, then why would you have slag. Slag comes from solidfied flux, and since flux core and mig are two seperate processes as defined by the AWS then I would think that nobody would be using FCAW for welding roll cages.Arguing with a Welding Engineer is like wrestling with a pig... after a while you realize the pig likes it
Reply:Just a thought...but maybe the NHRA considers the silicon islands left on the weld from solid wire welding to be slag.
Reply:beer can alloy=3104-H19, although the top is different more Mg, less Mn. it needs to be strong and brittle
Reply:Originally Posted by reddoggooseJust out of curiosity, why would NHRA say that welds need to be free from porosity and slag. I think we can all understand the porosity part, but if only MIG and TIG are allowed, then why would you have slag. Slag comes from solidfied flux, and since flux core and mig are two seperate processes as defined by the AWS then I would think that nobody would be using FCAW for welding roll cages.
Reply:I dont know about at other tracks (as Orlando is the only track I have ever run at) but here a lot of people are getting away with these cheesy bolt-together junk cages....Our tech inspector is the oddest guy I have ever met....  He wouldnt allow us to run with the N02 brackets we had (which were store-bought NOS brand parts, no zip-tie crap) But he lets a lot of cars in missing wheel studs and without battery hold-downs and things like that...I dunno why the NHRA rulebook notes that stuff, I just copied it verbatim to try to help out...  And I have had lots of arguments (usually with circle track "chassis builders") about flux core not being MIG, as they need Inert Gas...
Reply:Originally Posted by FordBuilderFLI dunno why the NHRA rulebook notes that stuff, I just copied it verbatim to try to help out...  And I have had lots of arguments (usually with circle track "chassis builders") about flux core not being MIG, as they need Inert Gas...
Reply:What sanctioning body is this spec Miata running under? I've been away from racing for awhile but I've never heard of Tig not being allowed. Usually mild steel cages got MIG welded and 4130 gets TIG only.
Reply:Originally Posted by tresiWhat sanctioning body is this spec Miata running under? I've been away from racing for awhile but I've never heard of Tig not being allowed. Usually mild steel cages got MIG welded and 4130 gets TIG only.
Reply:Originally Posted by olddadCan't say for certain but you would think SFI would know the difference between the processes. I have seen (online) where folks have FCAW a cage for drag racing purposes. I have seen (online) in welding forums where someone talking about FCAW kept referring to it as MIG. There seems to be a lot of folks that think if it runs a wire spool it's automatically MIG welding ?? I personally wish NHRA/IHRA would go back to the system of requiring weld tests of some sort to receive a "Manufacturers Stamp" to keep all the yahoos from building/welding on cars. I have actully seen firsthand a cage that was "trigger" welded !! I know a guy that had never welded in his life but he was a "certified chassis inspector".