Aluminum Welding Help

[Scubachef]

I'm fairly new to TIG so I have run into an issue that might have a simple answer...but I'm stumped and I know there are some great welders here... so here goes. I am building a sheet metal brake for another project I thought I would make out of Aluminium I had laying around. I am attempting to attach the legs I made to the main base. I can't seem to join the two and was hoping someone could explain what is going on.

So here is the backstory The main base is 1/4in 6061 and the "legs" are 1/16in aluminum scrap(so I do not know exactly what it is). I thought if I could focus the arc on the thick metal , heat it knowing I am not going to get fantastic penetration, and just melt the thinner metal into the base I could join the two without blowing out the thinner metal. When I strike the arc the tungsten immediately eats away like it would if you struck it without and gas. I tried two different tungstens and both did the same thing. I cleaned the first time with non-chlorinated brake cleaner. I thought it might be something to do with surface prep so I scrubbed with a wire brush and then wiped it down again but no change. I then ran a bead on a scrap piece of aluminium I practiced on previously to check to see if the welder was malfunctioning and that bead was fine. Here is the list of specs and settings I am using:

Eastwood TIG 200 set to AC
3/32 grey tungsten
100% Argon is set at 20
foot pedal at 140amp
Clearance Effect set at -1 and then +1, no difference
#5 alumina cup
pre flow is .5 sec

Here is a shot of the tungsten that is thrashed. This happened immediately as the arc was struck. At least a few mm were lost as the tungsten just kind of dissolved before my eyes.


Here is the work Piece. On the left I got a little bead happening the first try but the tungsten was trashed and I was just trying to glue the pieces together.. I was forcing it. The right is the last attempt where you see the buildup of filler. As soon as the tungsten went the arc looked like a giant cone and immediately melted the thinner aluminium so I tried to get filler in to plug the hole. Ugly and wrong..I know.


I pulled out a practice piece and ran a bead that you will see circled in red. No settings were changed, same type tungsten but a different one since the original two were beyond use, didn't even adjust the pedal just feathered it. Tungsten was fine.


I have accidentally struck an arc without the gas on before and what happened to the tungsten then was exactly what I saw here but the gas was on. I know it has something to do with the work-piece since the welder was fine on the scrap.

Is this somehow because of the thick base plate I was working with? Also, I am a definite newbie to TIG so any comments on the bead on the scrap is welcome, my travel speed was all over the place I know