TIG welding corners

I am assuming once again that you are welding aluminum.

The trick to starting a Aluminum fillet weld is to slowly bring up the amperage on the end of the filler rod until you melt off a little ball of filler that is resting in the corner, touching both pieces of metal. Now increase the amperage of the arc directly on the ball until it flows out to both sides, then proceed with your weld.

Actually, no, it is steel (I do not have an ac/dc machine yet). I can try this filler ball trick anayway, however.

Help me out here...you are using DC- ?

What thickness of base metal, diameter of filler rod, diameter of tungsten. How many amps are you running?

Patrick MTS

It works for DC and AC.

Yes.

This is one example where altering the angle of the tungsten point can help direct the arc in a more focused manner. The longer the point, the wider the arc and greater the chance it will dance around. The shorter the point, the more focused the arc will be. This helps keep things directed where you want it. Its a simple thing to grind an electrode and see if it works.

BTW, this is a real pain when welding aluminum in corners. Typically a pure tungsten with a ball on the end provides little influence on where the arc is directed. When in corners, the arc can dance all over the place. Using an inverter with the AC frequency cranked up and a lanthanated tungstens, arc dancing is no more. Tungsten stays sharp and the higher frequency keeps the arc more focused.

Indeed it is simple and I will try it.

I knew I needed one of those expensive inverters with adjustable frequency ;-) What frequency do you use?

My lanthanated tungstens don't seem to stay sharp even with the freq dialed up to 200 Hz and the bias set towards penetration. I'm using a 1/8 tungsten and welding 1/8 aluminum at around 125 amps ( a little less once the metal heats up)

What am I doing wrong?

I actually use the lowest frequency that I can get by with. The lower frequency, say around 100 hz and less provides a nice wet puddle. One thing the higher AC frequency does is decrease the amount of heat put into the work. So higher the frequency, higher the amperage needed to weld. The balance needs to be adjusted a bit as it appears you lose some cleaning action with higher frequency as well. I read an explanasion of this somewhere but can't recall off the top of my head all the details.

Using high AC frequency, 150 - 200 hz, has helped me on several occasions. I repaired a manual transmission housing where the tapered fill plug was overtorqued. This cracked the aluminum casting at the fill hole. There was some ribbing in a very tight area. Very tricky job to do. A balled tungsten and 60 hz AC would have the arc dancing around like it was at a rave party. Higher AC frequency and a pointed tungsten and it was still challenging but I was able to put the heat where I wanted it.

One last thing. Running an AC arc at 200 hz really screams. I have to wear ear protection or else that buzz will penetrate deep into my skull and induce a headache with an epicenter at the centroid of my brain.

It's been a while since I did a lot of aluminum. I don't recall how frequency impacts the heat at the tungsten.

With the current you are using, I would expect you to lose the very tip of the point. A small ball will form from the very sharp point. The dia of the ball will be much smaller than say the full 1/8 tungsten being balled. This will result in much improved control over the arc direction than a full balled tungsten.

Now I understand why some modern inverters come with a feature that reduces the noise of the arc!