Alum. welding info wanted

[wagspe208]

OK, I used to be a welding sob. 20 years ago. Mostly chromoly. I can lay a bead on steel, and fair alum bead, but not great. I am working on great alum beads...
I believe I have a setup issue causing my troubles.

I am butt welding .125 alum
I have a dynasty, 100% argon.
3/32 2% thiorated (first problem?)
Balance at 70 ish.
150 ish max amps
Freq set to 90 ish.

I can get a clean weld, proper balance, etc but the tip keeps blowing off. Splitting.
I use a gas lens mostly, but sometimes a #7 cup.

So:
1) Do I need different tungsten?
2) Is a gas lens better? (if room) and what size?
3) Is there a rule of thumb for cup size vs tungsten diameter?

I am pretty sure my first issue is setup. Laying a bead should be pretty easy.

I'm just practicing for future projects. Need to get back in shape for alum.
Thanks
Wags

[TJS]

Turn up the balance to about 74 or 75. You will keep a better point as well as more heat into the work and not the electrode. I use zirctungs on my dyn 300 and they hold up pretty good on alum and steel. Also try a higher frequency like 130hz or so.
T.J.

[acwd1950]

At the top of the page click on resources and then click on improving your skills and then click on tig resources. Then find tig handbook and download it. It is a pdf file and you can download it by chapters. It has came in very handy at times for me. Its well worth the time to read.

Steve

[wronghand]

Ya I would use a 1/8" electrode. 140 to 150 amps sounds right for a butt weld. I use either 2%thor. or 2% ceriated for everything. The Thoriatedtip will break down faster than the ceriated but you should still get many many arc starts before it starts to split.

The reason for going up to 1/8" instead of 3/32" is to prolong the life of your tungsten. The TIG calculator will tell you 3/32" is good but they're assuming you are using pure tung. with a balled tip. The diameter of the ball will end up being about 1/8" anyway within the first few inches of your weld. If your sharpening you electrodes for ALU typically you can go up one size from what the calculator suggests and it will work out just fine

[wagspe208]

I will step up on the tungsten diameter. I will also try the ceriated.
I thought 3/32 may be small. The tig calculator said that was ok. Makes sense it is rated for the balled end.
I was at a lower balance as the alum was slightly dirty. Really, this is a band aid on a problem. I should have cleaned it properly. I'll try that too.
Argon flow seems to be about right.
I'll try a few beads tonight.
Thanks
Wags

[wagspe208]

1) Tried ceriated tungsten. WOW. Big difference. LWS only had 3/32, but the 3/32 vs 3/32 was much better. Will order some 1/8" too.
2) Cleaned alum. This allowed me to turn up the balance.
3) Increased frequency. Uh... worked somewhat, still need to work with this.
4) Thought about what I was doing. I was actually welding 2 pieces of rectangle stock back to back, so while .100 ish thick, it was thicker at the corner. Duh.

Beads look nice.
Thanks
Wags