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Welding aluminium. Tack with the mig, Weld up with tig?


Steve 90

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Any alloy welding experts.

Does anyone know if I will have problems welding some 2mm wall alloy tube with the Tig after tacking it in place with the MIG. Its one of those trial and error fit type jobs and it will be easiest (as it needs to be done on the Landrover) to tack it all together with the alloy wire in the mig before Tig'n it all together. My concern is I have done simillar with mild steel in the past only tacking together with MIG then Gas welding. Everytime Ive tried to gas weld over the Mig Tack its caused problems. I dont know why, It just has.

So will it be OK to Tig over what has been tacked with the MIG?

Thanks.

Steve.

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When I was a sheet metal worker eons ago, we used to use soap to stop ally sticking to soft pads (many tears). Is soap still used? If so does that affect the weld. Our welder used to gas weld and I think cleaned the ally with wire wool.

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in case there is carp from the mig (soot or whatever).

In case?! there'll be loads, in my experience.

It's called 'smut' believe it or not :ph34r: . 5356 is particularly bad for it, but easier to weld with. 4043 produces less smut but you need to run it in at a rate of knots - around twice the m/s wire speed, I've found. In either case, increasing the gas flow (pure Ar) helps a lot.

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4043 leaves a weld that wont annodise because of the silicone content.........

(but its a nice easy grade to work with for the same reason)

easier to use flap sanders Alan - no cloggy, my fave cleaner for ally is a scotchpad material buffing wheel on a battery drill, quick and leaves a nice finish :)

I need to get out more :ph34r:

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Why not tack it with TIG to begin with?

Its surprising how much the smallest amount of dirt (or even marker pen ink) will effect the weild. One of my favorites is when you finnish the run lift the mask to see the charred half of a moth in the weild after having seen that irrisistable bright shiny light. :glare:

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