welding aluminum

Mike · 2004-11-21T03:39:24+00:00

Hi all, I have a need to weld some frameworks in Aluminum 6061 & 6063 extrusions and plate, up to 1/4" and some extrusion to 1/2" plate. There's almost enough of it to consider getting the equipment to weld it myself. This is hobby stuff not commercial so part of the deal is to be able to do it myself. Here's the problem. Never done it before. Years ago did a reasonable amount of gas welding in steel, mostly tube work race car and bike chassis, and some general buzz box stick stuff. What's the best method to weld this stuff? Mig? I've been looking at a lincoln 135 or 175 with an AL mod. would an average welder get a good result with either of these machines? Would a mig machine of this scale give a decent structural weld? Is there something else I should look at? Is anything from ( big intake of breath) HF able to do the job? thanks...

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Old Nick 21 years ago

On Tue, 30 Nov 2004 21:05:34 GMT, Ted Edwards vaguely proposed a theory ......and in reply I say!:

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Well all I can say is that reading these posts, my radius of gyration is becoming increasingly small, but my speed is being maintained. In the end my brain will probably exceed Yield Stress!

I do have to say that you guys may be arguing at cross purposes. I _thought_ that Ed was saying that tube stiffness is not the only thing. Wall thickness is important as well, because that will prevent buckling under certain circumstances.

I am trying to learn here, from minds that scare my dilettante little brain!

AFAICS the argument revolves around the fact that you can keep the same wall thickness or even nincrease it, using aluminium, and use a larger diameter tube to achieve the stiffness. You in fact need to do this.

Having a smaller diameter tube would presumably make a given wall thickness less likely to buckle. That feels right to me.

But would a steel tube of small diameter, having the _same weight_ as a larger tube of aluminium, have as strong a _wall_ as the alum one?

If you thinned the walls of the steel pipe, in order to allow a larger diameter for the same weight, the walls would _not_ be as strong as an aluminium tube of the same weight as the thin-walled steel one, with wall thickness strengthening as a cube of the thickness (?) while weight is linear. Looking at the wall as a bar of steel, aluminium would be stiffer than the same _weight_ bar of steel. (?????)

Hope I am saying this in a way that can be understood. trying to avoid having to learn a whole dgree's worth of engineering terms and conditions, by using gut feeling and laymen's terms.

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Ed Huntress 21 years ago

Here's the lab demo: Take a soda straw. Push on both ends. Watch what happens and write a description of it in your lab notes.

Then take an aluminum beer can. Place it on end on the floor, or on your forehead, whichever you prefer. Stomp on it. Watch what happens and write a description of it in your lab notes.

You now have completed the course in Failure Modes of Tubes of Widely Varying Proportions in Compression, and you're ready to design the Lotus 8.

Actually, Chapman already designed the Lotus 8, and wished that he hadn't. The Lotus 9 was developed into the Budweiser beer can and has changed life as we know it.

Ed Huntress

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Old Nick 21 years ago

On Wed, 1 Dec 2004 01:20:10 -0500, "Ed Huntress" vaguely proposed a theory ......and in reply I say!:

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Peuh! Boring!

Used the straw to drink the beer. As I wanted to ensure that the test was repeatable I tried this severla tims. Now the strwa is alread bnet cause I staempd on it. I reul...re...know this nillu... nuli... makes the test not vrey god.

msorry. Faliuer mode of a diffrent sot altogether.

Sory. That's...... shoobee _differen_ sot.

no kid!??

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Gunner 21 years ago

My life is forever changed because of it.

Whats a Lotus 9?

Gunner

"I mean, when's the last time you heard of a college where the Young Republicans staged a "Sit In" to close down the Humanities building? On the flip side, how many sit in's were staged to close the ROTC building back in the '60's? Liberals stage protests, do civil disobedience, etc. Conservatives talk politely and try to work out a solution to problems through discourse until they believe that talking won't work... they they go home and open the gun cabinets. Pray things never get to the point where the conservatives decide that "civil disobedience" is the next step, because that's a very short route to "voting from the rooftops" Jeffrey Swartz, Misc.Survivalism

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Ted Edwards 21 years ago

AFAIK, it's a flower that grows in CHina and Japan.

Ted

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Ted Edwards 21 years ago

You might want to get it. It's put out by Lincolm (the welder people) and, like most of their books, is both good and cheap. As well as unusually readable theoretical stuff, there's a lot of charts, tables, worked problems and comparisons of designs.

Correct. As with most things, if you go to extremes, you get into trouble. Just where that point occurs requires working through a particular case. My point is that it is not clear that going to aluminum will improve stiffness - you need to do the calculations for a particular case.

BTW, similar considerations apply to torsion.

Ted

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Tim Williams 21 years ago

And a symbol of...erm... *cough* fun :)

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

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Ed Huntress 21 years ago

Would I kid you? The 9-1/2 was *really* brilliant. It didn't make much of a car, because, in his never-ending quest to add lightness, he left off the wheels and seats. But it had a great sound system. It became the iPod.

Ed Huntress

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Ed Huntress 21 years ago

I don't know. It probably never made it off the drawing board. Or maybe it was one of the small open-wheelers.

The 8 was a one-off, a design exercise toward the purest possible space frame. It turned out to be a backfire, construction-wise, because it required a lot of add-on assemblies to be a practical car. But it raced, and it was a good one.

The 10, IIRC, was a tiny front-engined car like the 11. The Lotus 11 was a major design, one of the last of the little front-engined racing sports cars made for the 1100 cc class. Somebody is building replicas. It's a wild little thing.

Ed Huntress

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Gunner 21 years ago

Cars? Cars????? Homebrew racing cars?????

Who the hell cares about them?????

This whole thing has been about freaking cars??????????????

Christos on a crutch...airplanes, firearms, even sail boats...but cars????????

Your kidding me...right?

S*it..they havent made a decent car since my Rambler.

Gunner

"I mean, when's the last time you heard of a college where the Young Republicans staged a "Sit In" to close down the Humanities building? On the flip side, how many sit in's were staged to close the ROTC building back in the '60's? Liberals stage protests, do civil disobedience, etc. Conservatives talk politely and try to work out a solution to problems through discourse until they believe that talking won't work... they they go home and open the gun cabinets. Pray things never get to the point where the conservatives decide that "civil disobedience" is the next step, because that's a very short route to "voting from the rooftops" Jeffrey Swartz, Misc.Survivalism

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