Is Synchrowave 250 able to weld 3/8 aluminum?

I spent a frustrating afternoon trying to weld two pieces of 3/8 aluminum 6061 plate perpendicular to each other in a "T" configuration. I have a Miller
Synchrowave 250 and have done a fair amount of welding on thinner aluminum, but this was the first time I had tried anything thicker than 1/8. Machine was set for maximum amps, AC, continuous high frequency, metal was clean and gas was argon, but I just couldn't get a puddle to form that included both pieces of the aluminum. I tried using a 1/8 tungsten electrode, in case a smaller size was limiting power, but that didn't help. Just as it seemed close to forming a puddle, the metal seemed to sag a bit, the buzzing got ungodly loud, and the 50 amp breaker would trip. By then the entire weldment was very hot, but no weld. I was able to get a few short beads welding 1/8 inch-wall thickness aluminum pipe to the edge of the 3/8 plate, but it was pretty ugly. Was I simply exceeding the capacity of the machine? I had assumed that doing so would result in a lack of good penetration, but since this was just a bracket to hold a TV antenna, I was willing to live with that. Maybe, at least with Tig and aluminum, poor penetration, or insufficient amps, means no weld at all? Any ideas? Gary Hastings
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Now just for reference purposes. 3/8" = 0.375" = 375 amps for a flat butt weld. adding 30% (125 amps) for the inside fillet gets you to......500 amps.
Now even I know that that is a little high, so lets say more like 450 amps. Still since a Syncrowave 250 has a max output of 310 amps, you would seem to be sh@t out of luck.
Now....all is not lost. First, too small of a tungsten. Get yourself a 350 - 400 amp water cooled torch, that would be a #3 series torch. Get a 5/32" Zirconium tungsten, 5/32" collet and collet body, and a #10 cup for your #3 series torch.
Slide that tungsten about 5/8" past the edge of the cup. Yes I know that that is more than 3 times the tungsten diameter, but with inside fillet welds you can slide the tungsten out a little further since the gas with be naturally concentrated by the walls of the fillet.
Replace your 50 amp breaker with the 80 amp breaker specified by the back of the machine, so you can get full power from the machine You did read that pesky little plate didn't you?
Set your Syncrowave 250 on 310 amps. Polarity set for AC. Set the AC wave balance on 10. Continuous high freq. Use a Helium rich shielding gas mix.
Clean the metal completely with a flapper wheel or a stainless steel cup brush on a grinder. Bevel the bottom edge of the vertical piece to a 45 Deg angle. Use a propane torch, OA torch, ovenm or stove burner to bring the piece up to about 500 - 600 degF or when a drop of oil starts to smoke.
Now, wearing heavy gloves, use a 1/8" filler rod, and blast your arc into the weld joint . First tack the ends and then weld the rest.
I have a simpler solution for you. Buy a ready welder spoolgun and run it from your Syncrowave 250. Using 3/64" wire you can easily weld 3/8" aluminum. I have done it many times.
You are pushing your machine to it's limit in TIG mode. MIG welding aluminum doesn't require as high an amperage, and it is much faster.
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Oh just for reference I have welded 1/2" aluminum with my Syncrowave 250, but then I used all those tricks from my first post.
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Ernie: Any luck with the TIG reference material you were going to work on putting on a CD?
Lane
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Working on it. I will see what I can accomplish tonight.
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Have you tried preheating the aluminium pieces before welding? This may make enough difference. Use a big propane torch.
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Aluminum dissapates the heat too quickly to use TIG on that heavy material. I have used up to 400 amps trying to weld aluminum flanges to heavy aluminum tubing and could only get a very small puddle on the flange, not nearly enough to make a decent weld with. Use MIG

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jerzyjer wrote:

I've done this with my Thermal Dynamics 250 GTSW but I use 70/30 A/He. I understand that the He tends to give a hotter arc.
Ted
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try heating plate with a map gas bottle first
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Gee, I've always wanted a Synchrowave. I'm surprised that it is having trouble welding 3/8" stock. I just have a Lincoln Idealarc Tig 250 and I've welded half inch with no problem. I do use an 80 amp breaker, and I have power supply correction capacitors in the Tig 250.
Chuck
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