Welding Tips and Tricks

Power tig 250ex machine. I wanted to weld a 3/16 to 1/4 piece of aluminum plate to a piece of round tubing 3/16 thick wall. I set my machine back to ac with pulse at all the same settings I had when I was welding some 1/8 inch wall square tubing. I increased the amps of course. I grinded the metal and wiped with acetone. Ground my tungstons. Ground cable on. Fired off the Arc and it looked like the Arc was just sitting there cleaning. So I turned up the amps. Same thing. Turned up more amps. The metal melted and bubbled up from under the cleaning mess it was making. The melted aluminum looked like aluminum in color with black specs. Never formed an actual movable puddle / Shiney puddle. I don't get it. The only two things different are. I used my bench grinder stone to sharpen my mower blades and I use that for my tungstons. The other thing is the metal. Not from the same stock I got the 1/8 square tube from. Anyone have an idea why the puddle won't start? I adjusted the cleaning up and down which did not help.

your description sounds exactly like it's too cold, machine needs to be maxed at 250amps. Turn down your htz to 60. Higher equals colder weld. Floor the pedal. Should get a shiny puddle in a few seconds. If it's not new metal, then it's probably absorbed contaminants which you may be seeing as the black stuff coming out. Oh, also the grinding wheel or disk needs to be used only for tungsten. You probably introduced contamination to the tungsten during grinding
Also you can use a propane plumbers torch to preheat the plate to about 250°F. Get a IR non contact digital thermometer.

Thx. I'll give that a try and get a new tungsten wheel.

not enough amps
sounds like you are starting in the middle of the piece so
no benefit from an edge.
craig

Just dress your wheel and move on. Tungsten is harder than a womans head so you aren't really contaminating it bad enough to have the trouble you are having. Like motox said, more amps if you don't have the benefit of an edge. 250 amps for .250 material..at least.

Thx guys!

While you're turning your amps up, turn off pulse.

You don't want to limit heat input, you want a puddle in 3 seconds or less if possible.