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Mig, Tig or Gas


Grumpy
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Got to fabricate a couple of roll cages in the near future, one for a 90 that we are going to have a go at some challenge events with and a 404 Unimog that are playing around with.

Long time ago I gas welded everything, mainly seam welding Mk 2 Escort & Mantra body shells for the rally boys but also roll cage mounts, live axles etc. Then I discovered Mig and never looked back. Now I only ever use the gas bottles for removing stubborn bolts and the occasional mad gas axe moments. To cut a long story short the bloke that owns the farm where our unit is has given me full access to a full blown Tig set (AC / DC and lots of knobs) as he has never used it. Had a bit of a play and found it gives a real nice neat weld with very little heat transfer compared with gas.

What’s the main advantage with Tig over Mig other than neatness? Its seams to take me longer with Tig but I presume I will get quicker with practise.

On another note, I have never fabricated a cage from scratch. When you weld the various joints do you usually do a full root, fill and cap joint or just blast round?

Sorry if this post has turned into a war and peace epic.

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OK

My 2p worth, in simple terms, but I'm sure others who maybe do it for a living will add extra.

All forms desvribed will do the job, there are some pros and cons.

Cons.

Ability !

But it seems you are OK here, ie you can TIG MIG oe GAS weld, many (inc myself) cannot weld as well say with gas as with MIG, if this were the case then I would say use what your best at.

PROs.

Mig can be quick, simple and TIG GAS can get yoiu into areas that the MIG torch can't, a Good Gas or TIG weld IMHO alays (if done well) looks "Nicer" than a MIG Weld, but Gas does have a habit of setting everything on fire around it :lol: well, it often does when I do any of it :blink:

If your Using CDS then the annealling pre welding may mean GAS is a better route.

As for how to weld up a cage DO NOT just "Buzz around" the gap, it will distort horribliy, do a number of small tack welds, then work around the cage welding up small amounts on various tubes rather than one tube completely, this does make a huge difference to the distortion that will always occur, but can be moderated a lot

HTH

Now make way for the pros who will prob shoot me down

Nige

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I only ever use gas (at present anyway). It's slow, and heat generation is enormous, as will be distortion if you don't clamp efficiently. The plus side is that you can work a weld, and reduce the size of it without loss of strength. A good gas weld looks good too, although this is rarely a consideration. You would need a No5 nozzle for tubing that thick and gas consuption would be quite high.

I might make a cage in the future, and for that I will probably go and buy a Mig. I would suggest you use the weld method that you are best at.

Les. :)

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Thanks guys, will be having a bit more practice with Tig and see how it goes. Know exactly what you mean about twisting, it’s always amassed me how much a weld can pull. Going to get quite a bit of practice and there should be plenty of scrap at the end of it, it’s been a while since I have bent any tube. Still not decided if the cage for the Mog will be made out of Tube or box yet. In the old days everyone seamed to just use 2” Blue Band tube for their cages and if you wanted one a bit stronger you just upgraded to Red Band, what’s the norm (if there is one) for a challenge motor? I think the ARC green book still specifies Blue Band but I can’t find my copy I’ll have to look at their website.

You would need a No5 nozzle for tubing that thick and gas consuption would be quite high.

Les. :)

Only got No7's left now and they a quite a bit worn, think I need to pay a visit to BOC

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practice practice practice, having said that without doing a stint of training even mega practice will leave you with some grey areas in terms of techniques, prep and metalurgy - I personally think the best money and time you can ever spend is in training, doing a hit at college in the evenings will pay massive dividends, does entail devloping radical political thoughts and rebelling against your parents though :o

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