I don't always use a gas lens on aluminum.
In fact there are many situations where a standard #5 cup and collet body work just fine. Sometimes even better than a gas lens,
But for the particular weld in this video, I was using an air cooled 17 style torch.
Its a good all around torch for me and can handle 200 amps for brief weld but, it can get pretty hot at 175-200 amps if you weld very long at all.
So I decided to use a gas lens setup because the extra mass you get with a large diameter gas lens collet body helps keep the torch cooler...at least a little bit.
A 17 style air cooled torch is typically rated at 150 amps but I often go higher than that for short periods without a problem.
If I were to get an order for 100 of these parts, I would definitely go with a water cooled torch.
The weld is a solid aluminum plug welded on the inside diameter of piece of 1/4” wall thickness 2” diameter tube to form a corner joint.
I used 4043 3/32" filler rod. (FYI here is a great resource for selecting aluminum filler rod from Alcotec)
On a corner joint like this sometimes the main objective is to wrap the corners with the edge of the bead in a single pass.
That is why I rounded the tip of the tungsten and set my amperage to 200 and used a foot pedal to control my amperage.
I used all 200 amps at first but quickly let off to 175-185 amps once the part heated up.
I used a rounded 2% lanthanated tungsten electrode because it has a very high amperage limit.
When I am in the upper limit amperage for a 3/32" tungsten, rounding the tip seems to help maintain the same shape from start to finish and also helps to fan out the arc cone to wrap the corners on the joint.d
An outside corner on 1/8” aluminum does not require a super wide bead so I only slightly rounded the tip of the electrode for better arc starts and a bit more control.
A tee joint is a different story. Getting penetration all the way into the root of the joint can be a challenge.
So for the tee joint filet weld, I just left the tip tapered and allowed it to round off on its own.
Hope this helps,