Welding Tips and Tricks

I have picked back up on the Lincoln electric square wave tig 200 on some 1/8” 6061-T6 aluminum flat bar in a tee orientation. I am struggling to get the pool down into the root. I am following cleaning recommendations Jody put in his aluminum tig videos, holding a tight arc, 3/32 rod and 3/32 4043 filler, 150 amps, 67-70% balance, 120-150 hz frequency, blunt tip, torch angle 45 to the joint and 5 from “perpendicular”, and 13-15scfh. I start off at 1/2 ish pedal to get the cleaning action going for a few seconds then go to full pedal to start the puddle. When I do this, I notice the boomerang shape weld pool and trie as I might, I cannot fix it on the go. Any help is appreciated.

Make sure the material is cleaned with stainless steel wire brush and wiped with acetone or alcohol. I would turn down the freq to about 95/100 (giving a wider arc cone) and turn up the amps. Hold the torch so the tip is close and leaning so you are pushing the puddle, when it appears within a few seconds and motor along. You want the amps so you don't have to wait for the puddle to keep re-establishing, work with the pedal to maintain the puddle. Hope this gets you going.

By boomerang shaped weld pool are you talking about a convex or concave bead or are you saying your weld puddle itself is barely stable and wants to solidify on you?

Assuming you've done a cut and etch to verify you're not melting into the root I'd suggest dropping the frequency to 60-100hz. The higher the frequency the less heat you input, Jody has a couple videos showing just how drastic it can be and the first thing I do when I'm pushing a machine to its limits to weld thicker aluminum is drop the frequency when I can't turn the machine up higher. Assuming you've done the appropriate cleaning, lots of acetone and wire brushing with a stainless brush only used for aluminum I'd also raise the balance to 75%. When I actually have relatively fresh clean aluminum and go through all the effort of brushing or cleaning it with a flat disc I much prefer 75-80% DCEN for punching down into the root. When I have some old nasty aluminum that just won't come clean without wasting 8 paper towels and a quarter of a can of acetone. That's when I like 65-70% DCEN. I've tig welded aluminum that smoked and smelled like used motor oil by adjusting the balance accordingly.

Also I don't know how large your coupons are, but if they're decent size you might honestly need to set the machine to 160-170 amps for the extra heat to punch down in and simply back off the pedal towards the end. Generally I've found if you can go full pedal right up until the end and not need to slowly back off pedal as you approach the end you're probably running the first half of the weld way too cold. Aluminum is funny for lack of a better word, it melts at less than half the temperature of steel but is several times more thermally conductive, meaning you'll need more amps until the coupon starts getting heat saturated then you'll need far less and T joints require a lot more heat than other joints.

Generally I set my machine 15-20 amps higher at minimum than I think I'll ever need. And then I'll control heat using the foot pedal based on puddle characteristics. If you just max out the machine you won't have much puddle control but if you try to dial the amps in too precisely you'll either not have enough or be running way too hot towards the end if you're not controlling the heat with the puddle anyway.

By boomerang shaped weld pool are you talking about a convex or concave bead or are you saying your weld puddle itself is barely stable and wants to solidify on you?

Assuming you've done a cut and etch to verify you're not melting into the root I'd suggest dropping the frequency to 60-100hz. The higher the frequency the less heat you input, Jody has a couple videos showing just how drastic it can be and the first thing I do when I'm pushing a machine to its limits to weld thicker aluminum is drop the frequency when I can't turn the machine up higher. Assuming you've done the appropriate cleaning, lots of acetone and wire brushing with a stainless brush only used for aluminum I'd also raise the balance to 75%. When I actually have relatively fresh clean aluminum and go through all the effort of brushing or cleaning it with a flat disc I much prefer 75-80% DCEN for punching down into the root. When I have some old nasty aluminum that just won't come clean without wasting 8 paper towels and a quarter of a can of acetone. That's when I like 65-70% DCEN. I've tig welded aluminum that smoked and smelled like used motor oil by adjusting the balance accordingly.

Also I don't know how large your coupons are, but if they're decent size you might honestly need to set the machine to 160-170 amps for the extra heat to punch down in and simply back off the pedal towards the end. Generally I've found if you can go full pedal right up until the end and not need to slowly back off pedal as you approach the end you're probably running the first half of the weld way too cold. Aluminum is funny for lack of a better word, it melts at less than half the temperature of steel but is several times more thermally conductive, meaning you'll need more amps until the coupon starts getting heat saturated then you'll need far less and T joints require a lot more heat than other joints.

Generally I set my machine 15-20 amps higher at minimum than I think I'll ever need. And then I'll control heat using the foot pedal based on puddle characteristics. If you just max out the machine you won't have much puddle control but if you try to dial the amps in too precisely you'll either not have enough or be running way too hot towards the end if you're not controlling the heat with the puddle anyway.

Thanks for the quick responses. I will prep more coupons tomorrow and give the suggestions a try. I’ll keep y’all updated.

Bill Schaffley wrote: ↑Sun Oct 31, 2021 5:47 pm I have picked back up on the Lincoln electric square wave tig 200 on some 1/8” 6061-T6 aluminum flat bar in a tee orientation. I am struggling to get the pool down into the root. I am following cleaning recommendations Jody put in his aluminum tig videos, holding a tight arc, 3/32 rod and 3/32 4043 filler, 150 amps, 67-70% balance, 120-150 hz frequency, blunt tip, torch angle 45 to the joint and 5 from “perpendicular”, and 13-15scfh. I start off at 1/2 ish pedal to get the cleaning action going for a few seconds then go to full pedal to start the puddle. When I do this, I notice the boomerang shape weld pool and trie as I might, I cannot fix it on the go. Any help is appreciated.

simply to cold. not enough amps.
don't be afraid to set it max amps and use the pedal. stand on the pedal and drive it into the root. once its in you can back off and just keep the root flowing.

as mentioned lower frequency and less cleaning action (higher balance) means more heat available.
also consider what cup size you have, smaller cup size (eg 5) helps to.

On a 1/8 T joint I'd be setting the machine to 170-180 ish so the weld can be 'punched' into the root at the start then back off the pedal when things start running too hot.

Sounds like the issue your having is mainly not enough amps at the start to punch the weld down into the root.

Used to deal with that type of weld puddle often with my old 185 and the 1/4+ material the boss man wanted me to weld.

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Given you're complaining about the arc wandering, I'd look at clamping the parts down better to get a better ground. Make sure not to clamp the one part so as to heat-sink it to where it acts like it's 1/2" thick. You still need equal heat bleed in the parts, or at least not total cooling of one member and let the other melt. Especially don't overcool the top T portion and let the leg portion overheat. It's easy to melt away an edge.

There's a balance finding 'enough heat', to get a good solid root, but not too much so you melt the back side of the flat member.

While higher frequency does reduce total heat output, it does concentrate energy to a more focused point. Play with the balance of those two conditions also.

Also what kind of tungsten are you using?