I've been watching youtube vids of people gas welding aluminium and it looks bloody difficult...but how hard would it be to just tack joints. I have a friend who can tig me a fuel tank at work but he is too busy/lazy to do it unless its all ready to weld.

Most would TIG ally
My experience of gas welding steel was that it is a lot more difficult than Mig, get gas wrong and you have a liquid work piece
Ally is so soft that a gas torch would probably just blow holes in it

Don't be tempted to use one of the low melting point aluminium "brazes" such as Lumiweld or Technoweld for tacking as it won't mix with TIG welding and your welder will hate you for it
My welder calls it the Devil's spawn and will never let me forget the time I used it.

HTH

Neil

I tried years ago, molten blobs dropped out using a standard sized gas torch.

I watched someone making exhausts, he had a tiny gas torch and did a beautiful job with ease.

TIG is very localised heat, much hotter with more control which is why it's much easier, I can TIG Ali to a reasonable standard.

Hi.

I see 3 issues.


1.
With a gas flame it's difficult to get the two joint edges to "jump" and fuse together.
OK if your Trev D and have 20 years experience, but for us mere mortals the degree of difficulty is high.


2.
Gas welding uses a flux.
TIG welding over a fluxed joint makes the joint appear to "flare" making it difficult to see.


3.
I wouldn't advise tacking a tank together completely, then welding in one go.
I would weld in inlets and outlets, baffles, and longitudinal seams before putting the ends on.
At each stage distortion can be dressed out before moving on to the next stage.




I hope this helps.

Paul G

(professional welder)

Hmm more complicated then I thought. Oh well it was a nice idea...

I am thinking, after watching Mega Factorys on Discovery (Tesla) of getting the bits to convert my Mig to weld ali.

Anyone done any ali mig welding?

Yes lots and lots
You will need a big amp welder pure argon a nylon liner change the drive wheels to smooth wheels
Jacko

quote:

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Originally posted by jacko
Yes lots and lots
You will need a big amp welder pure argon a nylon liner change the drive wheels to smooth wheels
Jacko

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all i can say is practice practice and more
what thickness alloy are you thinking of welding ?
Its not as hard as some people think the welder needs to be turned up more then you would think so dose the wire speed
The alloy needs to be VERY VERY clean use a stainless steel wire brush
I would not go below 14g alloy under that you want to use TIG