[OliverR]

Hello,

I want to weld some 0.025” 6061-T6 aluminum, on a homebuilt aircraft I am working on.

To practice, I ran beads on some scrap pieces, without a problem. Not pro level, but I felt that I was in control of what I was doing.

However, when I laid a second piece on top of it and tried to weld them together, this was virtually impossible. No matter what settings, how I held the torch or on which area I tried to focus the arc, the upper piece would melt away before the lower piece would form a puddle.
When I tried to melt some filler on the lower piece first, hoping that it would flow into the joint, this also didn’t work.

I spend quite some time practicing, watched tons of videos, read through the forums, but no success. I am now wondering, if I do something wrong with the preparation of the two pieces or if my setup is not suitable for this job.

This is what I have:
Eastwood TIG200 AC/DC welder
Blue, 2% lathaniated 1/16” electrode, ground to a sharp point, but I also tried to ball it
1/16” 4043 filler
100% argon gas
#7 gas lens

Settings:
15 cfm gas flow
25 amp (I also tried more and less)
-2 clearance effect (I also tried much more and less)
0.5 second pre-flow, 5 seconds post-flow

Parts preparation:
Wipe with laquer thinner
Clean with Scotch Brite wheel or stainless steel brush
Wipe with laquer thinner again

Some of the test beads on the 0.025” sheet metal:



After the parts had cooled down, I cleaned them, turned them around and positioned them for welding:


How would you go about welding these two parts together? Do I need to change something in my equipment / process?


The other topic is, that want to add two more fittings to the fuel tank, which is also only made of 0.025” 6061-T6 aluminum.
This is what the factory installed fitting looks like:


This is the type of fitting I want to install:


A friend suggested that I should heat the fitting up with a torch and then start to weld at the tip of the red arrow, letting the filler run down to the sheet metal. What are your thought on this?
I will order a few extra fitting and practice first, at over $3 / piece, I however want to keep scrap at a minimum.

Finally, note the fine weld in the edge of the tank. It goes along the edge of the tank’s side wall and the bottom. How would you go about making such a weld?

Thanks for your help in advance!

Oliver

[weldyM]

The only picture I'm seeing is of the fitting. An image of the specific joint you're welding would be helpful.

I wouldn't use lacquer thinner, I'd use acetone. Search 'acetone vs lacquer thinner'.

If that welder doesn't go down to somewhere around 5 amps on AC you'll have a really hard time welding something that thin.

I would also purge it.

Here is some .025" I've welded. All of it purged

[tungstendipper]

Oliver,
The only picture I can see is the last one.

[OliverR]

@tungstendipper

Thanks for letting me know.
I uploaded the pictures to my Google Photos account. I'll check the settings, if your reading the forum from work, access to Google Photos might however also be restricted.


@weldyM

Your welds look beautiful!
I don't want to take any chances and will therefore simply get Acetone, just to be on the safe side. I will also try to grind the tungsten at a wider angle, to get a more focused arc.
The weird thing is, that I can start a puddle just fine, add filler even to a point at which I have a good sized bubble on one piece, but am not able to make it flow to the second piece with which I want to join it. It is as if the second piece would immediately be covered in the white stuff, surrounding the original puddle and repel the added filler. When I apply more heat to the second piece, it would melt away, before forming a clear puddle.

A friend of a friend is a very experienced, semi-retired welder, who now instructs a two local colleges. He will come to our house next week, to look at what I'm doing but to also give it a try himself, with my machine. If it turns out that my machine is not suitable for this thin aluminum, I can also try his fancy $4,000 Miller TIG welder.

Welding the thin aluminium was originally only a ‘nice to have’ but now it has become a skill I want to master.