MIG welding aluminium.

with mig it is not easy at all to get anything acceptable with portable units, especially in thin stuff. Try it for fun, but don't expect much, don't forget you will also need a bottle of pure argon to run it with, possibly different tip size and sometimes a different liner for the gun.

If you want to weld aluminium at home with any real degree of success then get an ac tig welder. (which will also do dc and give you lovely welds in steel.

+AD4- Any tips?

Don't bother Dave is my tip :)

I'm not bad with a mig, but when I tried ally welding it was all just far too quick for me. The wire speed has to be set to warp factor 9, and I just ended up with big black blobs, when I wasn't left with a hole that is....

There's some more constructive info here

+ADs-)

I recently posted about TIG vs MIG welding on stainless steel in Pistonheads.

The comments still apply but with aluminium there are even more factors in TIG's favour. AC current TIG welding automatically removes the oxide layer from aluminium as the arc is created which removes the need to clean it thoroughly immediately before welding. The wire speed needs to be so fast with MIG it's often a struggle to get a clean weld with good penetration rather than just depositing huge lumps of weld in the wrong places or blowing right through if it's thin material. It's especially problematical if the metal thickness is not constant everywhere such as when you're trying to weld odd shaped objects together where the joint geometry keeps changing. With TIG you can always see the penetration and adjust the current with the foot pedal as you traverse the work. With MIG you have to keep stopping and starting to adjust the welder and every new start means more soot and crap in the weld as the arc strikes up.

With TIG the arc is created separately from the addition of filler material which you can add as and when you need it so it's much easier to get the proper penetration and also the right amount of filler material in the joint.

I can, of a fashion, stick two bits of steel together with my MIG but it ain't pretty and I do it as infrequently as possible. Having a small gasless MIG rather than a big one with proper gas bottles and no autodarkening helmet turns it into a pretty hit and miss one handed affair while I struggle vainly to see what the hell's going on through the cheap plastic mask that came with the welder which I'm holding in the other hand. I wouldn't even entertain trying aluminium which is many times harder to do and requires all the gear to be changed from a steel setup. Having watched my mate effortlessly TIG up corroded or damaged aluminium cylinder heads for me it's a no brainer which system to use, especially as he doesn't charge me for fixing anything cos I help him with other stuff.

There are some things in life which give you great satisfaction to master yourself so you don't have to rely on other people and some which a sensible man realises are a waste of bloody time just to prove a point. Using a MIG on aluminium is a bit like reverting to flint cutting tools for doing your DIY with when you could be using hardened steel ones and carbide tipped saws. No matter how much you spend on the right wire, a decent helmet, plastic sheathed cable, expensive bottles of argon you're still trying to do a job which is better suited to another process. Why reinvent the wheel?

Anyway I've already said I'll get anything you want welded done FOC if you drop it off and I'll shape the base of that boss properly for you on the mill with a flycutter so it sits nicely on the radius of the tube you want to stick it to. All the machinery's sat doing nowt since I retired so I'd actually welcome something to play with on it. You don't have to do anything in return. A mate was chucking out a perfectly good widescreen tv so I don't even need my old one repaired anymore. I'll just ditch it.

This site has some info

The set-up page seems to indicate that it's a nightmare to get the wire to feed without tangling.

-- Rich

Remove socks and trousers before replying

Brilliant post. I feel quite a bit better about my pigeon-shit gasless migging skills knowing I'm not the only one who finds it difficult to get a good finish.

Useful for getting a rusty shed through a MOT, making simple structures out of mild steel tubing, or bodging exhaust repairs (that also involve gun gum). But then I'd go and look at the welds on my bike and think why can't I do that.

Didn't realize you used AC with TIG. Never tried it but the problem always seemed that you would need at least 3 hands. An autodarkening helmet sounds like the business-- what's that something like those photoreactive glasses that used-car salesmen wear only on a larger scale?

The one I have has just two settings - normal and dark. I think it is LCD

- it works instantly. They're essential for an amateur. But still don't give me the skills I want. ;-)

>

Tig can be ac or dc, you need ac for aluminium because the refractive oxide melts at a higher temp than the aluminium (IIRC)

A self darkening helmet is virtually a must have for diy type welding, the screen darkens in a split second as the arc strikes and lightens again when it goes out, so you can see exactly what you are doing. Nowadays they are not too dear, my first one was 200 quid 25 years ago, now they start at about 60 quid.

Domestic migs can give very nice welds when set and used correctly, I don't like cored wire gasless types though and it is easier to get good results with a gas unit. Primarily the gas free cored wire types were developed to give reasonable welds in windier conditions. Better to weld indoors with gas shielding, using a good quality reactive gas like argoshield is much better than using CO2 which is what usually comes with the little units. Cleanliness is always a good start to any welding job, people tend to think that since it will be red hot a bit of paint or rust will make no odds, but of course it does. The welds on your bike are probably tigged by machine or by someone whose sole job that is and under perfect conditions.

[...]

It also means for MIG you could use both hands on the gun which could be quite a bit steadier.

Yes, I had heard that. Gasless is also quite convenient for the occasional DIYer though.

I remember reading somewhere that it's different gases for different metals.

Yes, I noticed that quite early on. Best to use an angle grinder to get everything properly shiny first. Then start with a couple of spots and if possible look around the other side to see if you're getting the right amount of penetration. The angle at which you hold the gun is extremely important-- it's easy to put bubbles of weld on things without actually joining them together.

Yes, I should think it's a machine.

Anything produced in quantities of more than a few hundred will be done robotically.

I once attended an industrial robot training course in Sweden; they demonstrated a setup with a pressed steel lightweight motorcycle frame and petrol tank. One robot moved the pressing, another a pointer representing the welding head.

The speed and accuracy left me amazed, even after 40 years of working with industrial production machines!

Chris

The biggest improvement is normally getting something (ie not sold by SIP for under £400 & takes a Eurotorch) with a decent wirefeed. I really must take my old Migmate to the tip.

I took a gamble a few years ago and bought the cheapest one I could see on eBay. Cost 27 quid plus a tenner postage from California, IIRC. It's ruddy brilliant and still working perfectly. Settings go from 1-9 on a continuous scale. I use about 8 in dull weather and 3 in bright sunlight.

Sorry, I absolutely disagree. I always to try to do my welding outdoors these days and no longer suffer the fits of sneezing and headaches that welding used to bring on. And unless it's really windy, my welds don't look any more crap than normal.

That leads to all sorts of intriguing mental images!

:-)

I did ponder over how to phrase that!

Chris

Well let's say 'weld out of a draft' then, because the wind blowing away the gas shield is one of the causes of rough looking welding.