[Alex Blair (RIP)]

Stu..
Aircraft are welded aluminum skins using butt welds all the time..using a heli-arc (Helium) arc welder with a foot pedal power control.(Better stability)

Heliarc® welding is a form of welding introduced and perfected in the 1940s. The reason the welding process is referred to as Heliarc® welding is because the welding process requires the presence of two substances. These substances are helium, an inert gas that is used for the shielding of the weld, and an arc that is generated through the implementation of a tungsten electrode. The electrode receives a constant power signal from the welding machine.

The process by which gas was used along with an electrical current to create an arc across two materials was first introduced in the 1930s. Though primitive, gas welding proved to be an effective means of fusing two metal items together. It created a much stronger bond than most fastening or connecting methods of the time.

The process of Heliarc® welding is also widely referred to as TIG welding, for tungsten inert gas, or as GTAW, for gas tungsten arc welding. The original process had its problems, but over the course of time became perfected as the primary means of joining metals. Today, Heliarc® welding is the most common method of welding used when the materials being fused together are hardened ones, such as stainless steel.

The use of helium gas in Heliarc® welding is done to shield the weld area. This is necessary to keep both the electrode and the arc compressed into one direct point of contact. This creates an intense heat.

In some cases, a filler material is used to fill open spaces between the materials being welded together. Heliarc® welding equipment has, however, come a long way since its inception and because of the advancements that have been made it doesn’t often require any form of filler. As a result, the process in which TIG welding is carried out is a more slow and precise process than most other forms of welding. The technique behind the process takes much longer for some welders to learn.

The versatility of the Heliarc® welding process is one of the biggest contributors in the popularity of that specific welding process. The quality and durability of the weld compared to others is another. Since Heliarc® welding fuses two materials together without the use of a filler material in most cases, the bond between the two materials joined through this welding method is stronger than the bond that most other welds can produce.

Once you have learned to Heli arc..you won't go back..
I started welding that way back in the early '60's, on scrap aluminum in the metal shop in the RCAF on the hanger line when I had a few hours off I would go play with the aircraft welding machines..
You could butt weld two pieces of aircraft aluminum skin butt welded and it looked like one piece..
Strong like Bull..