Which welder should i use to build a airplane frame?

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rv7charlie

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Companies like Maul use MIG on their 4130 fuselages, but those guys are highly experienced welders. You might want to do some reading about the pitfalls of using MIG if you're not an experienced welder. Or even if you are, in some cases. You should see the 'caulked' joints on the Bush Hog brand finish mower I bought. And welding aluminum *structure* can be done, but you do need to have a good understanding of welding's effect on strength/fatigue values.

Anyone heard of using MIG on aluminum aircraft structure?
 

trimtab

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I have gas, mig, tig, and stick in the shop. I use MIG for thicker plate, and find gas or Tig is about the same for thin wall tubing for speed. For tig, Ar gives the best welds, but a 2% CO2 bottle makes it easier to flow the puddle in hard to reach areas. C25 means blowouts and porosity.

Gas is fine, and I only prefer the tig for comfort. The skills are very similar. You'll need to stress relieve a tig welded frame with a torch anyway. The torch mostly self relieves.

Aluminum? TIG or a spooler MIG are the only way to go. The spooler makes it easy.
 

TFF

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Welding aluminum structure opens the biggest can of welding aircraft parts one can open. The general problem is once you weld aluminum, you pretty much turned it into aluminum foil until it can be heat treated back to strength. Not cheap. Not just around any corner. That’s why you see rivets and bolt on brackets. Welding structural aluminum has been done, but it it’s not for amateurs. It’s not for professionals in their garage with no other facilities.

While that welder might be great for welding A repair on a fence line, I think you will be surprised how maxed out it will be for welding stuff.
 

Fiberglassworker

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Companies like Maul use MIG on their 4130 fuselages, but those guys are highly experienced welders. You might want to do some reading about the pitfalls of using MIG if you're not an experienced welder. Or even if you are, in some cases. You should see the 'caulked' joints on the Bush Hog brand finish mower I bought. And welding aluminum *structure* can be done, but you do need to have a good understanding of welding's effect on strength/fatigue values.

Anyone heard of using MIG on aluminum aircraft structure?
I have never heard of MIG on aluminum aircraft structures, But I have used MIG with pulse on 6061 commercial structures, bear in mind that the heat affected zone HAZ takes the temper back to the AQ temper, so you go down to 17000lb and 7000lb yield at that point. If you can live with the loss of strength at those points, then that may be acceptable.
 

rv7charlie

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I'm not sure what the link to that Lincoln article was supposed to imply. But if you read the sections about 2000 series 6000 series & 7000 series (what we typically find in a/c), the article says what most of us have been saying; it's really 'iffy' to weld aluminum a/c structure, unless you know exactly what you're doing.

The only welded a/c structure I'm aware of was the Valley Engineering Backyard Flyer. While I love the overall concept of the plane, I'm not sure I'd want to fly one as built, without having the engineering calcs shown to a structures guy.
 

challenger_II

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The Howland H-1, and H-2, were welded aluminum structures. Is one reason most people shied away, and the aircraft weren't a commercial success.
Without some pretty serious test and heat-treating equipment, welded aluminum airframes are a guessing game.
 

J.L. Frusha

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The article shows that some Aluminum alloys are better suited for welding, even specific types of welding, as well as certain pitfalls. Most are not.
 

rv7charlie

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That's not *all* it says. Knowing that a material can be stuck to itself with heat is *waaaay* less info than what you need to know whether the process (or the material itself) is viable for aviation use. It can even be misleading info.
 

dog

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The thing I have learned about MIG is that a gap between the pieces bieng welded is a good thing
a few wire diameters,and keep pushing wire,and the puddle onto both sides,with a hard wire machine like my ln-25 running off a miller bobcat,its no problem getting flat,shiny,splatter free,welds.
The newer MIG guns have a ball joint at the heel,and
allow for a more natural movement,and can be made
up to match any MIG welder.
I am doing metal work full time,and there is a 100% write off for up to $5000,per year for tools,I will get a full set of torches for all my welders,MIG,TIG,Stick,and Gas,propane and acytelene and a bigger selection of inert gases,I use them all and it pays to have gear that works nice,faster,better.
 

J.L. Frusha

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Technically speaking, rod welding is MIG welding, as the flux coating the rod also forms the gas shield around the weld.
 

Pops

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Coldlap (lack of fusion) at edge of filler metal, gas inclusisons in both filler and base metals, carbide precipitation throughout (hardspots & cracking).

Before going to Babcock and Wilcox's welding school to weld tubes for their coal fired boiler power plants. I worked at a high rigger building the boilers for several different large contractors. Installing a large steel beam truss about 120' long and 8' wide at about 300' from the ground floor. Had a wire rope choker attached to a steel plate on one end. The large steel plate that weighed about 300 to500 lbs was welded on 3 sides with a large fillet weld. The large mig weld looked very good and was painted where it was made in a shop. The weld was a Mig coldlap weld and I ended up dropping the steel plate about 300' down in the building to the floor. Could have easily killed many people. It hit and damaged a large steel duct and ricocheted to a place that missed everyone. There was weld penetration one place about the size of an aspirin.
I do not have a mig and never will. If I can't weld the part with the tig, I will stick weld it.
 
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