I found a Lincoln Square Wave 175 on Craigs for a great price, I know 175 amps isn't much when it comes to tigging aluminum but Jody's talked about a 50/50 argon helium mix to be able to puddle and weld pretty thick stuff. and I've some 3/4 in channel base plates with some 1/4 wall pipe sticking straight up, so its pipe to plate flat t-joint and a bunch of coped joints. I've got a jug of helium and wouldn't be to much trouble to hook up two bottles. All this stuff has been pre-welded with mig 4043 wire on 6061 t-6 and every weld is cracked or broken not me,somebody else.
So am I gonna need 50/50 to weld this stuff? because has to be strong ,any input remotely related would be great , thanks , John
Just a couple welders and a couple of big hammers and torches.
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Otto says preheat. With steel I break out either my rosebud tip, or if it's a loader bucket a big propane torch that throws a 4" diameter 2'long flame. I have a I.R. gun gives me a temperature reading. How do you heat aluminum? Isn't it hard to keep it clean enough?
I preheated my last bit of 1/2" work with an oxy/acet cutting torch. Put the heat adjacent to the weld on both sides (or in the O.P.s case, on the heavy section), but not directly on the weld zone. Then, wire-wheel or brush just before welding.
but Jody's talked about a 50/50 argon helium mix to be able to puddle and weld pretty thick stuff. and I've some 3/4 in channel base plates with some 1/4 wall pipe sticking straight up, so its pipe to plate flat t-joint and a bunch of coped joints. I've got a jug of helium and wouldn't be to much trouble to hook up two bottles. All this stuff has been pre-welded with mig 4043 wire on 6061 t-6 and every weld is cracked or broken 
not me,somebody else. 
