what amperage to tig 0.25" aluminum?

That sounds about right. You're going to need between 240 and 300 amps to get something acceptable but might be able to get that down a bit with a good pre-heat. You're right that your breaker/cord situation is the problem, that 50A breaker will cause you no end of frustruation when trying to TIG aluminum.

Also, what kind of electrode are you using? 1/16" pure tungsten is much too small to be using with 1/4" aluminum. It isn't the root of your current problem but it will be once you get enough power to do the job.

If you have some thinner aluminum, you might do a little practise on it. Or cut off about 3 inches of your tubing and try that. Or preheat the aluminum. Your problem is that the heat is being sucked away by the aluminum.

If you are wanting to weld sections together, I would go to a larger electrode and a breaker that will let you use all the current your welder will supply.

Dan

Thanks for the fast replies. I'm using a 2% zirconiated tungsten size

1/16", because that's what I've been using for the steel. What size electrode would you suggest for 1/4" aluminum? I bought the welder years ago from a guy who was welding aluminum t-tops for boats, and he used a 1/8", but that was for lighter gauge tubing.

The guy who owns the shop where I keep the welder is ready to put in a new electric panel. What size breaker do I need to use the full 300 amps of the machine?

thanks, Dave

Check your manual.

For Miller XMT 300CC, they recommend max breaker size of 80 amps at

230V single phase. Just a data point for you. If your welder is not inverter type, your breaker requirements may be greater. i

You can probably get away with a 3/32" zirconiated but I'd go with

1/8". IIRC a 100A breaker and more importantly the wiring to handle it are needed. When I moved up to my Syncrowave 250 (310 Amps max) that's what my electrician reccomended and it's served me well.

Dave,

1/4" Aluminum and thicker is a good application for DC electrode negative TIG with Helium. You can probably get by with no preheat, a 3/32" electrode, and about 200 amps. Of course preweld cleaning of the aluminum is very important since it is the reverse polarity portion of the AC cycle that helps break down and remove aluminum oxides.

1/8" tungsten

I had a couple of those machines back when they were still being sold. I don't recall ever tripping a 100A breaker welding up to 1/2" AL - same for my present non-inverter square wave machine. As you've seen, a 50A or 60A circuit is a problem at higher current settings.

Ned Simmons

100A according to the manual. You can get your own copy at if you choose.

I have the same welder and have never run it up that far, but I have never tried to weld aluminum.

JW