Looking at fabricating up a manifold and exhaust system. My welding skills are non existant and I have no equipment. I have someone at work who will tig weld for beer - a useful bloke to know.
My question is if I borrow a cheap nasty stick welder with a suitable stick material could I tack all the bits together to test and adjust and have everything lined up ready for a final tig welding. Would it contaminate the weld area using two different processes?

I find mig easier and you can get stainless mig wire and the correct gas shield

yes i can get mig done also although there is no SS wire at work so I would have to supply it (don't know how easy it is to change). But my main issue is whether I can tack weld with an cheapy arc in the garage at home then bring it in to get it finished

Stainless needs shielding or it crystallises, you can get arc rods however you need a decent machine and its not suitable for thin metal so unless you are skilled and practiced it will end in tears and wasted metal.

I suggest you cut the tubes and wrap each join in masking tape, one wrap will be enough to hold it together then take to you mate, he can then peel back and spot weld before finishing off.

You cannot do this for the whole thing as you have to weld in order or you end up with inaccessible areas, for instance inside the collectors so you may find it cheaper to source something that is already made unless you have access to lots of free bends.

Of course the balance of money between making your own and buying could be put towards a nice little DC TIG set, in which case you stand a much better chance at DIY, although TIG also requires skill and back gassing.

Good luck.

Regards Mark

I've used Armoid rods to tack stainless exhausts and then over welded with TIG. Just make sure there is no slag around the tacks before you TIG over them.

lots of info in here:

http://www.euro-inox.org/pdf/map/BrochureWeldability_EN.pdf

you can tack it together with normal mild steel mig, make sure the tacks are not huge, just grind the welds back a bit before tig'in

I just finished a welding course to up my skills and learn to tig, I'm with clanger!!


Thanks

Aaron

Seconded on the mild steel mig option. Stick welding/tacking for the uninitiated is tricky and will all end in swearing and throwing one's toys out of the pram.

[Edited on 12/5/13 by Litemoth]

If you tack it with stick it will leave big blobs inside the tube, and you are likely to blow through a time or two due to the thin wall.

I would go with the tape idea and make sure your tig man back gasses the pipes, which will leave a nice smooth weld inside as well as outside.

Al.

I welded bit of my SS exhaust last night with a stick.
Worked spot on, more than happy with it, not as pretty as tig but it'll do its job.
So Id say yeah, tack it.

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Originally posted by Aaron_n_Sim
I just finished a welding course to up my skills and learn to tig, I'm with clanger!!


Thanks

Aaron

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You can tack/weld stainless material with mild steel filler rods quite successfully, i.e it wont fall apart, but it will contaminate
the stainless and go rusty.....kind of begs the question why bother using stainless tube in the first place.

You will also get a nasty blobby back weld inside the tube, which upsets gas flow, hence the reason for back gassing with TIG.

I will get some rods and experiment. Something like this be suitable?
10 x 1.6mm stainless steel arc welding rods grade 316 | eBay

Its not exactly going to break the bank if I try and fail

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Originally posted by luke2152

quote:

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Originally posted by Aaron_n_Sim
I just finished a welding course to up my skills and learn to tig, I'm with clanger!!


Thanks

Aaron

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So the mild steel tack won't cause problems with different metals? I had heard something about dissimilar metals causing issues

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