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Outside corners in aluminium, technique question

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Outside corners in aluminium, technique question

Postby clavius » Mon Jul 03, 2017 3:18 pm

A big part of why I got a TIG machine (Lincoln SW200) for use in support of other hobbies and stuff that I do. One of those things would be the ability to build small custom sheetmetal enclosures for electronics and the like. I know a shear and brake are the best ways to manipulate sheetmetal stuff, but I don't have much access to those nor do I really want to get them to add to my shop for the fairly infrequent use I would have for them. I am a marginally experienced TIG welder at best, so this is also a way to get some practice on non-critical stuff. Besides that, welding stuff is just fun.

Anyhow, I am in the process of laying out a little rectangular aluminum box for a project. The material is 0.060" aluminum (6061, I think, don't recall but it is a known weldable flavor anyhow) I have seen videos of guys doing similar welds on outside corners with the parts clamped to an aluminum block. So I tried this on some scraps with pretty OK results. They were overlapped and fusion welded. Not perfect, but not utterly embarrassing either.

My question is this: Should the backer piece be a block that comes right to the inside corner of the two parts I'm trying to weld? Or would it be better if the block had say, a chamfer on the edge such that the two work pieces were not touching it at the joint? Or does it matter very much?
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Re: Outside corners in aluminium, technique question

Postby Arclight Ironworks » Mon Jul 03, 2017 6:05 pm

clavius wrote:.... I have seen videos of guys doing similar welds on outside corners with the parts clamped to an aluminum block. So I tried this on some scraps with pretty OK results. They were overlapped and fusion welded.....


Several ways to attack the OCJs (outside corner joints). Since your Aluminum is thin, recommended you envelope one edge against the other. And yes, install blocking flush to the ICJs (inside corner joints) of your assembly prior to arclight.

Images below for work earlier this year show .040" 5953-H32 Aluminum. Fused with 1/16" 5356 filler. Recall running these at ~ 60A, 68-70 Balance, 110Hz, with 1/16in 2% Lanthanated Tungsten on a CK Worldwide Series-18 FlexHead torch. Notice the black flecks in the weld line. Surface contamination. Did not wipe down the filler prior to use.

The 2in x 2in x 12in 2024-T3 blocks provide the "internal backing" discussed above. You do not/not have to use Aluminum for the backing, but we prefer to use Aluminum/Copper for chill blocks. Especially for stainless steel.

Fitup for these welds is critical and needs to be tight. The root of the welds......no images, sorry.....were approximately three-quarters penetrated, IIRC. Going for CJP (completed joint penetration) for our application was not in the cards.

Also, recommend you use filler for these applications. We did however tacked, without filler, in four locations prior to weldout.
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Re: Outside corners in aluminium, technique question

Postby clavius » Mon Jul 03, 2017 8:46 pm

First, thanks very much for the very informative and detailed post. Very helpful, gave me a great starting point for settings and such.

I tried using pretty much exactly the settings you outline, the only difference being that I was using 4043 filler as that's what I have in 1/16" on hand. I was just doing a bunch of practice runs using scraps of the same metal I'll be making this from. They were clamped to a 1x1 aluminum bar as a backer and i was doing more of a "lay wire" rather than dipping as my coordination is still not great.

As you can see from my bit of modern art in the photos, not 100% awful, not all that great either, but somewhat heading in the vague direction of good enough. For what this will be, anyhow.

I need a lot more practice.

In any event, I need only in this case to get the pieces to stick. Pretty sure I can always flap-disk them into workable shape with some additional practice.

Thank you again for taking the time to reply. Most appreciated and helpful!

-Al

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Re: Outside corners in aluminium, technique question

Postby cj737 » Tue Jul 04, 2017 9:45 pm

Aluminum filler doesn't "lay wire" very well. The ambient heat from the cup and welding tends to melt back the filler unless you are constantly jamming it back into the puddle. Better to focus on holding the rod at an angle to your puddle, dipping the filler into the puddle, withdraw it, then move the arc forward. Keep your amps low to allow you time to get the rhythm right.
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Re: Outside corners in aluminium, technique question

Postby motox » Wed Jul 05, 2017 6:40 am

those angles look difficult to prop for, you might want to set up a simple
corner you can move the torch along smoothy.
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Re: Outside corners in aluminium, technique question

Postby clavius » Wed Jul 05, 2017 9:44 pm

Thanks for the replies.

Motox, when I did those they were set up such that the joint was horizontal, so that I could easily support my torch hand along the edge of the table and sort of slide along. The odd angles you see are just the result of the oddly shaped scraps I was using as these were just practice pieces.

So most of the irregularity in the welds is simply a result of my poor welding skills more than the odd shapes. Sad but true... :)

Thanks again for the input, all. Much appreciate you taking the time to respond.
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Re: Outside corners in aluminium, technique question

Postby bowleggid » Thu Jul 13, 2017 8:06 pm

Hello Clavius,
I didn't notice anyone mention settings in the responses I read. I also have a SW200 and am practicing OCJs on aluminum, using only a piece of steel square tubing & some clamps to line up the aluminum sides. So I don't have backing all the way into the inside corner, but there is a bit of a heat sink - just not nearly as good as Al or Cu backing.
I've noticed that I don't need a highly focused arc (= higher freq. setting) on these, but it probably depends on the thickness of the base metal. I use lower freq. -- like 80 - 90 hz -- for 1/16" or thicker Al, but with a 3/32" electrode, & just use the pedal to regulate the amps -- & I try to set the max amps where it'll give me enough heat to make tacks at the ends, but not blow thru.
Finally, from what I've observed in Jody's videos of Roy Crumrine welding OCJs, -- & same for KaneKid on Instagram -- when you see the puddle, it's time to GO! You move as fast as the puddle will allow, & dab, dab, dab -- keeping the puddle width consistent, end to end. I know, easier said than done.
Good luck,
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Re: Outside corners in aluminium, technique question

Postby 5th Street Fab » Sat Jul 15, 2017 11:44 am

clavius wrote:A big part of why I got a TIG machine (Lincoln SW200) for use in support of other hobbies and stuff that I do. One of those things would be the ability to build small custom sheetmetal enclosures for electronics and the like. I know a shear and brake are the best ways to manipulate sheetmetal stuff, but I don't have much access to those nor do I really want to get them to add to my shop for the fairly infrequent use I would have for them. I am a marginally experienced TIG welder at best, so this is also a way to get some practice on non-critical stuff. Besides that, welding stuff is just fun.

Anyhow, I am in the process of laying out a little rectangular aluminum box for a project. The material is 0.060" aluminum (6061, I think, don't recall but it is a known weldable flavor anyhow) I have seen videos of guys doing similar welds on outside corners with the parts clamped to an aluminum block. So I tried this on some scraps with pretty OK results. They were overlapped and fusion welded. Not perfect, but not utterly embarrassing either.

My question is this: Should the backer piece be a block that comes right to the inside corner of the two parts I'm trying to weld? Or would it be better if the block had say, a chamfer on the edge such that the two work pieces were not touching it at the joint? Or does it matter very much?

Hey so I know this post is a week or 2 old but thought I'd give some tips!

To answer the main question it depends what you need. If you don't want burn through then a nice squared edge will help keeping from burning through. If you want burn through then you'd want a chamfered edge.

Second with aluminum and especially 6000 series aluminum you need to add filler or it will Crack. If you can get some 1/8" 5052 aluminum just to practice on that would be good to practice on I like 3/32 filler on anything 1/8" or larger. 5356 looks nicer when used but it doesn't flow as nice as 4043 or 4943.

Third for your fit up flush would probably be fine but I still like to go corner to corner. It gives you a nice little Valley to fill and it's much stronger in the end.
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Fourth you can use lay wire but it's a little tricky. You need to move your torch in a back and forth motion while inching forward. Basically get a puddle started then add your filler and while your still pushing it in move the torch back a 1/8". And while still putting pressure on the filler move the torch forward 1/4" and let it take some filler, then move it back an 1/8" and repeat. It's hard for learning welders though. And hard to tell if your washing into the root.

Hope this helps.

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Re: Outside corners in aluminium, technique question

Postby clavius » Sun Jul 16, 2017 10:02 pm

Thank you both very much for taking the time to reply. This is some very helpful info and photos.

For what I am doing at the moment, strength is not super critical as this will be just a small instrument enclosure that will be sitting on a bench. It mostly has to only hold itself together if that makes any sense. Not having burn through is probably better in this case so I guess I'll keep the square corners.

I have 4043 filler in 1/16" and 1/8" on hand so I'll try with that. I think the corner to corner fit up you show is worth a try, I can imagine having the little valley to fill might make it somewhat easier to do. While I have my doubts that my welds will come out looking anything like what you show here, I'll certainly give that a try.

I'm not sure "lay wire" is the correct term for what I had done, but it was pretty close to what you described. Worked OK, but not great but again that is likely my lack of practice as much as anything else.

bowleggid, if this exercise has taught me anything, it's "KEEP MOVING!" I do still have to get used to the fact that when welding thin stuff like this things happen pretty fast and if I dawdle, well, that's a mistake. I am getting to where I don't need quite so much conscious thought in working the pedal, it seems the less I think about it the better it goes. Once I start thinking too much about it, I mess something else up!

Anyhow, this is quite a learning experience for me. It is humbling and slightly frustrating. I have no particular expectation that I'd ever earn a living doing this sort of stuff but is a very cool skill to be working on. I have not been back to it for a bit but hope to get some time in over the next day or so. Working for a living sure gets in the way sometimes.

Thanks again for the tips, this is great info and I very much appreciate that you guys take the time to share your experience.
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