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Thread: MIG welding Aluminium
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13th April 2010, 07:15 PM #1
MIG welding Aluminium
Hi all, it has been a while.
I have been busy at the river house. Managed to build my second last gate from security fencing materials, burned off the powdercoating, got the lot sandblasted and powdercoated again. Turned out commercial quality. Welding the hinges to the frame and getting them powdercoated too was a nice touch.
In between welding and banging and grinding and being a pain in general, I managed to go up and down the river in my tinnie enough times to discover that my long leg engine tends to dig into the sandbanks more often then I would like simply because the boat has a short leg transom. So the prop is hanging 5" below what it should be.
As it is a busy time of the year for me, I decided to take the boat to a workshop that builds stairs and handrails and other stuff in aluminium and SS, and got the guy to weld a plate and lift the transom leveled with the gunwale so now I have 20 inch transom. Easy peesy.
However, I now got the bug to want to modify my poor tinnie into something more to my liking and for that I will need to learn to weld aluminium with my MIG. I have to say that the workshop that welded the transom shut, uses TIG and I asked him about MIG only to hear that MIG is schaise...well, his opinion but he was UNABLE to weld a hole in the transom left by previous screw because he said the aluminium was too old and contaminated and the more he tried the more it opened up.
I found that hard to believe, but solved the problem with a few rivets and a lot of Silicone and covered the lot with a new sleek transom reinforcement board, bolted with SS 5/16 bolts, covered by a checkered plate for good measure. Suck on that one!
So to the point...if I have one. Can I weld aluminium with a MIG? The boat is probably 2mm thick bottom and sides, gunwales are probably 3mm.
I want to make a structure for a steering wheel, and mount a single seat at the front and get rid of the first bench seat.
Perhaps fabricate a petrol tank.
Hooroo
Marc“We often contradict an opinion for no other reason
than that we do not like the tone in which it is expressed.”
Friedrich Nietzsche
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13th April 2010, 08:50 PM #2Senior Member
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Hi Marc,
Well the simple answer is yes you can mig weld aluminium.
I have attached some photos of some 2.5mm to 2.5mm ally welded with 1.2mm 5356 aluminum wire.
But....This was not an ordinary machine that a home handyman would purchase but rather a industrial pulse welding mig welder.
But none the less yes you can weld ally.
I have a list of top 10 (now it's 11, seems to be growing).
Tips for mig welding aluminium.
Which can be found here:Mig welding aluminum
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14th April 2010, 08:08 PM #3
Hi there and thank you for your reply...
Good tips, seems it is not too hard.
I have a CIG Transmig 250. Should I change the liner and rollers and tips or should I buy a spool gun?“We often contradict an opinion for no other reason
than that we do not like the tone in which it is expressed.”
Friedrich Nietzsche
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14th April 2010, 08:51 PM #4Senior Member
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Well what is the cost of a spool gun, vs the new liner and rollers etc.
I would for the peace of mind (wire feeding) get a spool gun. Downside is that they only hold those 4" diameter type spools. And it is always cheaper to buy a larger full sized spool. They are about $85-$90 bucks for 1.2mm 5356+gst at the moment I think.
But will you ever use up all that ally wire?
The spool gun will be the best option for small jobs, but for more workloads it's probably best to set the machine up for ally wire. I was speaking to a guy the other day and he was just in the process of shortening his tweco no4 mig guns from about 3.6meters(I think thats how long they are) down to about 2.5meters.
Peter
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14th April 2010, 09:05 PM #5
Well, I mainly weld steel. I am - was a blacksmith stickwelded all my life and am re-learning to weld MIG. Aluminium welding will probably be only a small part of my activities. If I ever get serious like building an allo boat, I suppose Ill buy a shorter gun lined in teflon and keep it separated only for allo.
A spool gun is about 300 to 500 dollars though. Not cheap. Perhaps it is cheaper to buy a new gun for alloy. Is it value for money to have disposable gas canisters or not?
http://www.nationalwelding.com.au/mi...pare_parts.htm
It seems that buying a dedicated gun for alloy will be cheaper than a spool gun. Rollers and tips are cheap. THe only thing left is gas. I don't want to pay rent for something I will use very little. Perhaps I can rent a smaller gas thing.“We often contradict an opinion for no other reason
than that we do not like the tone in which it is expressed.”
Friedrich Nietzsche
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14th April 2010, 09:10 PM #6Senior Member
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Is it value for money to have disposable gas canisters or not?
Being smart here, but you don't see any workshops using those disposable canisters.
And I don't know how much weld you could get out of one of those canisters? It might not be enough to get all your boat modifications done? Probably good for a few bits though.
Off the top of my head. you can rent a gas bottle for about $12 ish a month then + the cost of the gas. You would only need a small bottle, about 1 meter high. Not sure what the cost of the Argon gas would be.
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14th April 2010, 09:14 PM #7
Yes, perhaps just hire a small bottle.
I posted a link above, it seems I can buy a gun for 100 to200 dollars way cheaper than a spool gun.
PS
I read on you tube a guy that teaches how to weld alloy and he talks about heat sink using thick bars or plates of brass to make things easier and not having to rush too much?“We often contradict an opinion for no other reason
than that we do not like the tone in which it is expressed.”
Friedrich Nietzsche
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14th April 2010, 09:30 PM #8Senior Member
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Yep that would probably make sense as ally is something like 6 times more affected by heat (could not think of the right word).
Well when you do a single pass, if you go back over it again as I found out when setting up a machine, there is so much residual heat left there that you really have to let it cool down fully before you go again. Otherwise, plop. And this extra heat reall has an effect on the weld bead profile etc.
See the ally does not glow red hot.
Make sure to take plastic protective film off too.
Just get some scrap aluminium and practice and you will be able to get it no problems.
And the torch must point the way you want to move/weld. And you can try with the angles that you need to have the gas flowing in front of the weld puddle. Then it will be clean with no soot. If it is perpendicular or the other way you will get lots of black soot.
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14th April 2010, 10:35 PM #9
Hi Marc
Using a shortened cable and new gun assembly is the way to go.Shortening the gun cable reduces liner friction which in return reduces wire feed speed/amps.
2.5 metres is probably as short as you would want to go.I have done it on a single phase transmig.
2mm is getting light for Mig on aluminium.I would be go vertical down like the clappers.You might to to find this out before committing to some fairly big outlays.
Contacts tip need enlarging and the use of a Teflon liner is mandatory.I used 1.2mm and enlarged to 1.3 with a drill.
When welding wire diameter at the contact expands in its diameter so bigger tip is necessary or wire snarls will occur.
Keep the cable straight and .I can't remember but i thing you said you had a travelling wire feeder.
If so consider suspending it and that will help keep cabling straight.
That all I can think of at the moment.
cheers
Grahame
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14th April 2010, 11:24 PM #10Senior Member
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If you can get them use proper contact tips that are for aluminium welding.
Binzel have them, OTC have them, Tweco I think do. Bernard do not. For them use the 1.4mm tips with 1.2mm wire.
Drill only if you really have to. I don't recommend it at all. I know one fabshop who will buy all 0.8mm tips and when they wear out he puts a 0.9mm drill through it and uses them that way. He is welding with self shielding gasless wire though. Hey , works for him.
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