250EX and TIG aluminum

[baldysm]

I am fairly new to welding and got a 250ex awhile ago. I tried welding aluminum yesterday and it was a disaster.

There are 2 big problems. It looks like I am getting cleaning action, but it's pretty hard to get a puddle started. I don't have a problem getting a puddle in steel. I am using extruded 6061, no finish on it. I tried welding on a machined surface and there wasn't really a difference between that and the unmachined mill surface.

The other problem is that I release the trigger, and the arc never stops. I've sat there for 10 seconds and the arc keeps going and going, never sloping down. It's not broken until I pull the torch too far away from the piece. If I don't pull the torch away fast enough, it blows a hole in the edge of the piece.

I've used both blunt and pointed tungsten. The pointed becomes blunt pretty quickly.

Here are my settings:
100% argon gas at 20 lpm
AC with 120 amps
4T
pulse off
AC force 0 (it was 5, but I read it should be off for TIG. Might be acting a bit better after I made it 0, but hard to tell)
AC frequency 100
AC balance 50
pre flow 2
post flow 5
up slope 2
down slope 0
start amps 120
end amps 0
spot time 0
spot off


I'd say for sure that I had some settings wrong, or that I'm doing something wrong technique wise, except for the arc never stopping. Maybe it's a machine problem.

With steel, everything works fine. The problems I have, I am comfortable that they are caused by lack of skill on my part.

Any suggestions as to how to proceed?

Thanks

[performance]

I've used both blunt and pointed tungsten. Pointed
100% argon gas at 20 lpm: Way wrong. Need only 5-7 lpm for any TIG process in ordinary conditions
AC with 120 amps: Ok to marginal for 1/8"
4T: No foot pedal? Torch switch only? If torch switch are you releasing the switch to up slope or trying to stop the arc?
pulse off: Good.
AC force 0 (it was 5, but I read it should be off for TIG. Might be acting a bit better after I made it 0, but hard to tell) Does not matter
AC frequency 100: Might try 120, but 100 should be fine.
AC balance 50: Wrong. Need to try about 30%. At 50% you will burn tungsten.
pre flow 2: Probably too much. Just need .5-1 second for most welds.
post flow 5: OK, but you could use up to 10 seconds.
up slope 2: Again, depends upon foot pedal or torch switch.
down slope 0: Fine for foot pedal, need more to prevent cracking on aluminum if using torch switch to fill crater.
start amps 120: Why? Too high...makes hard starts.
end amps 0: Again, Why? If using foot pedal ok. But if not then it should be 20 or 30 amps.
spot time 0: Irrelevant if spot is off.
spot off: Yes. ok.

I think that you should probably review the manual on the 2T/4T/Foot pedal operation. When you use 4T, releasing the trigger upslopes and increases the arc. You have to press again and let it down slope. Be a good idea for the other settings too.

What tungsten are you using? What thickness are you using? Foot pedal? I assume you aren't using it by context, but your settings on some things don't make sense and would suggest that you were or at least had tried to and forgot to change your settings back.

[Blaster]

I don't see where you say the thickness of the 6061. But, yea, 120A could be low for a start (Alum takes like twice as many amps as the steel you're used to)

Crank 'er UP! (and see if the puddle appears, you're looking for a "shiny" spot more than what the steels color difference would be)

[baldysm]

Ok, I made a buncha changes... and nothing really changed.

My current set up:

pointed 2% thoriated tungsten, grind marks are length wise, pointing towards the end.
100% argon gas at 7 lpm
AC with 100 and 150 amps, see picture description below.
4T: No foot pedal. My foot pedal has not worked since day one. I get no gas when I use it.
pulse off: Good.
AC force 0
AC frequency 100:
AC balance 30
pre flow .8 or so
post flow 8
up slope 2: Again, depends upon foot pedal or torch switch.
down slope 4:
start amps 80
end amps 25
spot time 0: Irrelevant if spot is off.
spot off: Yes. ok.

Picture notes:
All I tried to do was start a puddle. The top spot was at 100 amps for about 10 seconds. The bottom is 150 amps for about 10 seconds as well. I don't have a picture, but I also tried 200 amps and never got a puddle.

I tried to feed weld rod, and aluminum just balled up on the end of the rod.

I am trying to butt weld 3/8" square aluminum.

I don't claim to be an expert in the least. I'm still learning and have a long way to go.

[performance]

1st, if the foot pedal isn't working, we would have replaced it. 2), I am not sure if you are using the 4t setting correctly. Please detail how you are starting arc, and pressing button etc to weld. 3) You AIN'T going to even begin to butt weld 3/8" aluminum at anything less than 250 amps or so...that's a fools errand that you're on there. No wonder. 4), You're going to need no smaller than 1/8" tungsten. 5) If the aluminum filler is balling, it's not the machine's fault, it's the operators. You are either holding too much torch angle in the direction of the filler, or you are holding it too close to the puddle. If it is balling when you are adding it, then it is either too small for the heat you are using, or you are adding it in the wrong place. 6) You've done no prep work to the metal, or at least not enough. If you can still see the writing on the metal, it isn't clean enough.

I'd suggest you go and watch a few videos on aluminum first. They are out there, and start with something thinner, way thinner, 1/8" or less.

[Steve]

What you need to do is take a course at a local community college or other place that offers tig welding classes. Vocational schools often have welding courses so check there too.

I went to the Lincoln Electric school to learn to tig and it was worth every penny.