Crappy Bead w/ Miller Spoolmatic 30A

I tried tacking some ears onto a Muncie transmission with my Spoolmatic 30A after meticulous cleaning of both the tranmission and also the
6061-T6 ears. I have had the gun for a year and just decided to hook it up. Gun is positive as per the directions and ground is negative. 20cfh on the argon and a roll of 4043 in .035". Tip is correct and ground was good and I gave a substantial preflow of argon before striking the arc. Gun at about 10 degees from veritcal and pushing.
Lots of smoke and a bead that looked like Mount St. Helens. Zero penetration and a black soot on each side of the weld bead. The gun was set as per the specs for 1/4" aluminum. The transmission is 365 aluminum and is quite weldable. The gas is good because it is the same bottle I run off of my TIG machine.
I then tried it on an old scrap transmission after cleaning it also. I got the same results.
Anybody have any idea what is going on here?
Any help or tips greatly appreciated.
Thanks, Steve
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My experience with trying to weld automotive aluminum is that there is too much oil/dirt/stuff in the metal. You can clean and clean, but you need the power of a TIG to really create a molten crucible where it can boil out. And then there's the contamination that's coming in from the back of the piece being welded. I never had much luck with my Miller Spoolmatic except for welding 1/4" or thicker flat aluminum in a flat position. Then the welding characteristics would change as the base metal got heated up.
I hear of guys all the time who can weld aluminum with MIG. I never had much luck with it.
Steve
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says...

And it's not going to be pretty, though you can usually get it stuck and even leaktight. Crucible is a good description. The black crud rises to the top, and if you're lucky you can quickly sweep some of it away with the rod at the same time you're trying to replace it with good (better?) metal.
But greasy engine parts are a joy compared to welding on an aluminum bodied bait truck. I had my first shop near a ferry landing for the offshore islands. The lobster bait dealer from one of the islands would stop in for repairs if he had time to kill while waiting for the boat. Nothing like heating up fish gurry that's been festering inside the tailgate for who-knows-how-long.
Ned Simmons
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Ned Simmons wrote:

Three words - Supplied air respirator
Pete C.
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If fewest number of words is the criteria for the best solution then you beat my eventual answer to the problem of unwanted jobs. Remote location, no sign, unlisted phone. <g>
Ned Simmons
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On 28 Aug 2006 21:46:16 -0700, " snipped-for-privacy@aol.com"

Did you check polarity?
Gunner
"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."
"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion). -Buddy Jordan 2001
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Hmmm, me thinks i've welded Al with my old spoolmatic electrode negative.

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I'm not familiar with your welder model, but sounds like a polarity issue, contamination of the area, or (likely) just plain sinking all the heat out of the weld due to the mass of the casting. JR Dweller in the cellar
snipped-for-privacy@aol.com wrote:

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