New to TIG, trying to weld aluminum with no success

[crmorse]

Hi, I'm new to TIG, I can stick and MIG pretty okay. But for this project I need to weld 2" aluminum angle stock. To get started I watched a few weld.com videos and read some stuff and then broke out some old aluminum stock to start running beads. I got this old stock from my Dad so don't know exactly what alloy it is. It files and saws like any other aluminum I've used so I don't think it's anything special.

The first night I got a whole bunch of mess and tried a whole range of settings with no luck so I came back in and rewatched the TIG videos (first watching was a while ago). Started over tonight per new learnings but still had issues. I'm asking here for help on what I doing wrong.

First is probably my welder (Lotos LTPDC2000D) which is DCEN only. I know AC is strongly preferred but from my reading, it's possible, particularly when dealing with thicker metal and my end project is 2"x2"x1/4" angle.

Setup:
I cleaned the metal pretty good with a steel wire hand brush. I snapped of the contaminated part of my 1/16" red tungsten and reground the tip. First test piece is 1/8" thick so I set my welder to 125A and 100% argon to 25 CFM.

Results:
The first piece (top) is 1"x1"x1/8" angle. I cleaned a stack of mild steel and clamped it all to my table so I would be working in flat orientation.
Weld #1 - I struck the arc and waited for the pool to form, I thought I saw it and I noticed the material was starting to form a depression so I started moving. I tried dabbing with 5% silicon aluminum rod. I think I got one dab in before the end balled (likely from me withdrawing it too far). The material started melting further, faster, and wider so I stopped.

Weld #2 - basically the same thing, I got a few successful dabs in before the rod starting "stringing" like hot mozzerella cheese when I withdrew it.

At this point I discussed with my brother (also a DIY welder but zero TIG experience) and we agreed it was possible that piece of metal might have been something weird. I rummaged around in my scrap pile and found a piece of 1-1/2"x1/2"x1/8" 'C' channel that we agreed seemed promising. Cut off a piece and cleaned it pretty good with the brush and started again.

Weld #3 - my auto helmet went dark at the first spark of the HFT spark and I stuck the tungsten to the metal. Snap, grind, reset.

Weld #4 - I think it was this point that I turned my amps down to 85. I reasoned that if AC should be at 70% penetration/30% cleaning and since I'm running DC I have no cleaning "amps" I should reduce the recommended 1A/thou by 30%. This time I also kept a shorter arc, probably less than 1/16" and I started moving sooner. I managed to get a few dabs in before the filler got stringy again. Also, the 3/32" filler is comically huge compared to the short arc and 1/16" tungsten, I probably need to get thinner filler and a thicker tungsten. Anyway, only made it another 1/4" before the dreaded gorge started opening up. Note: Since I wasn't sure if I had an actual weld bead I did take the wire brush across the first part of this afterwards which is why it looks so roughed up in the pic.

Weld #5 - I reasoned that I was moving too slowly (don't have a foot pedal yet, it's on the wishlist) and the heat was building up fast in such a thin piece of metal. I started moving sooner after the start. Too soon, I think since there's no shiny metal this time. I tried a few dabs with a smaller piece of wire I have (aluminum electrical feed wire--doesn't seem promising) and as soon as the gorge started opening I rapidly increased my feed speed. By the end of the metal I was moving comically fast and the only thing that happened was a bigger & deeper gorge.

So... am I on the right track with anything here? Or do I just need to give up without an AC machine? If that's the case, is there any possibility of using those special aluminum sticks for SMAW? I just need to build 4 standoffs to mount a dock ladder, this isn't for anything life threatening.

 

[bmaverick]

AL is funny. Come in various grades. Wonder if you have machine grade and not the weldable grade.

https://www.youtube.com/results?search_query=tig+weld+aluminum+tricks

 

[etpm]

With your setup you are not going to get good welds. First of all, to get good welds on aluminum with pure DC argon gas won't work. You need helium. Secondly, you are using 2% thoriated tungsten when you should be using pure tungsten. Thirdly, you should be using at least 3/32 tungsten for 1/4 aluminum.
I have done pure DC welding of aluminum with argon and the welds were pretty bad. And I am very good at TIG welding. Lots of hours at school to learn. Helium works so much better. But you need to use lots because it is so light it rises up away from the weld. With pure DC and helium and VERY CLEAN aluminum stock and filler metal you can weld very fast with large beads.
Without the cleaning action of AC you are not going to get good welds. You might stick stuff together but the welds will be bad welds, low strength, and not to be trusted.
Eric

 

[yomax4]

An inverter will run basically any tungsten. I recommend 2% Lanthanated but this setup might be better if you just use aluminum stick rod. Trying to do Aluminum with DC/Heluim will be frustrating for you to say the least. Aluminum stick has a couple secrets and tips to work well just as any process. Good Luck..

 

[ruffdog]

Should be using the green pure tungsten electrode and 100% argon gas. You say you are grinding the tungsten....to a point like welding steel? We would always melt a ball on the end for aluminum. As for the settings on the welder, they are also different for aluminum.

 

[LD1]

DC + 100% argon + red tungsten is a recipe for failure.

Old school as pure/green tungsten. But alot of the newer stuff also works....like blue or grey....but never the red.
Then you either need to get an AC welder (best results) or switch gas to helium blend for "ok" results.

I am assuming the basic equipment requirements weren't addressed in these videos you watched?

 

[crmorse]

So I called my local welding supply. They don't have any bottles to sell and even if I did find one somewhere else, it's $100 to fill with helium. This project isn't worth that hassle for what would likely be a poor outcome anyways.

An AC TIG is outside my budget right now and while I do have a Miller MIG machine getting a spool gun for it is about the same price as a new TIG.

Any other suggestions on how to build this? It's a vertical aluminum dock ladder anchored from the top so I only need to build four 11" horizontal stand-offs to space it away from the wall. I could built them out of steel but I'm not sure how to fasten it to the ladder without adding holes to the aluminum. It's decent thickness but I don't want to add a weak point and I'm concerned about rust or corrosion from exposure to elements and the dissimilar metals.

 

[crmorse]

@LD1, as a newbie to TIG I didn't realize the differences AC/DC would make at first. When I did I learned about that next and arrived a helium about the same time the responses came in here. I've yet to see anything that really explained the proper applications for each type of tungsten but that's moot now anyway given the helium situation above.

 

[Mark @ Everlast]

A proper sized bottle of helium is more than a 100 bucks. You need a lot of flow rate with Helium. One guy priced a bottle of helium and was going to use DC. He was quoted 500.00. He bought a new AC DC machine because someone misled him about DC. He figured after a couple of bottles of helium, he could have bought an AC/DC unit to begin with.

 

[crmorse]

@Mark @ Everlast I looked at your machines last night. I like your Lightning MTS 225, do you take trade-ins? lol.