[welddoc88]

Hobbyist welder. I need to tig 20 gauge sheet metal to schedule 40 pipe (1 1/4 inch OD, approx 1/8 inch thick wall). Not having much luck. Need advice please!

[tweake]

a couple of things, one is the standard thick to thin focus on the thick and wash puddle up onto the thin.
you can also use your filler to cool it, if your using thick filler (eg 1/16") then you can do it like your brazing and weld onto the filler.
don't forget chill bars. a chunk of aluminum backing fitted tightly, and i do mean tight, will help keep the thin sheet cool.

[welddoc88]

Tweake
Do you mean use silicone bronze filler wire to braze or do you mean some other technique I should use because of the large thickness mismatch?
Thanks

[tweake]

Tweake
Do you mean use silicone bronze filler wire to braze or do you mean some other technique I should use because of the large thickness mismatch?
Thanks

its not brazing, its a technique. using an oversized filler to absorb some of the heat.

i'm not a pro so i often do not have the right size filler for doing small material. but i found that by melting the big filler, like you do when brazing, it can help manage the heat. its kinda like melting the filler onto the weld, then welding it. that way your arc is on the bead which is thicker than the thin material, and being its connected to the thick material it helps wick some of the heat away. its like the old trick of starting the arc on the filler.

that also helps when your fit up is not perfect. i forgot them mention that perfect fits up make it a lot easier to weld thin stuff.

also as a lot of cheaper machines, like what i have, do not do low amps very well, running pulse at a high freq helps cool the arc.