Using the mig to tack weld the frame

[Roscoe]

Gday,I would like some input from more experienced heads than mine,can I to use the mig welder to to tack the frame together.I am a very experienced mig welder and was using the oxy to custom weld exhaust pipes as a lad but have never used 4130 before and it would seem that low amps from the mig to assembly the frame and then use the oxy to finish up would be a lot quicker than tacking up with oxy.I have purchased a 200 amp acdc tig machine but until I become proficient with the process I will use a flame as it is more controllable in the heat department in regards to the pool size. Merry Xmas to all, Cheers Ross

[M Lightsey]

I don't like to use different types of welding in the same weld. The tack from using MIG will be small and while it might not matter, you'd be mixing filler rod types when you finish welded it. Not sure if the fillers are compatible or not, or what the reaction of the MIG filler would be when you remelted it with gas.
I'd say pick a method and stick with it.
My $0.02
Mark

[Roscoe]

Gday, the mig wire I have is er70s6 so I can't see a problem with the oxy but if anyone could let me know if there is a problem with mixing the er70 with mild steel filler rod. Cheers Ross

[mtaylor]

I don't know mig welding so this may be a dumb question, but is there a mild steel wire available for the mig?