Aluminum bead width?

I have a question regarding what dictates the width of a aluminum bead. I ve been trying jodys tig aluminum drill on 1/8" 3003 the best i can do is 3/8".
I know i can (weld) aluminum but i cant get the bead width that wide with out burn in through ill get some pics up tomorrow.but its a good shiny puddle ive tried pointed tungsten and balled havent tried flat tip yet. 4046 filler, 2% thoriated 3/32, gas lens plenty of coverage 10-15 cfh,amps about 150, freq about 12 0clock and i also tried various other settings, balance 30-60%,
this is a brand new piece of aluminum . Givfe me some pointers if you got em
thanx in advance

for one, balance is too high. It's a clean piece of aluminum....doesn't require a lot of cleaning action. I try to leave mine as low as possible for what I'm working on so more of my heat is going into the work, not the tungsten. Temperature and amount of filler are going to be the big things to determine bead size. You will notice if you keep the same amps on a row of dimes that the bead starts off a little high and cold, as the piece heats up the bead flattens out and washes further out from the center and will get wider as you go along. Looking for consistency which is why you use the pedal to decrease amps as the piece heats up and you can keep the bead width consistent. Sharpen to a point then put a small land on the end for aluminum. Otherwise tungsten does funny things with AC and a sharp point at any appreciable amount of amperage

yeah i got yah there except the flat spot part, i cut some off the same piece of aluminum for a outside corner weld its alot easier to weld with a sharp tungsten than a dull (flat spot) one same thing on a inside corner. i will play with the balance tomorrow. the thing i dont get is when jody starts welding it looks like he gets a wide bead as soon as he starts right out of the gate and his tungsten was all split up. i was tryin 3/32 filler and 1/8.maybe i need to take my time i was tryin to hurry up ill try it tomorrow.

floor it when you start out and you can get that wide bead....I just don't see why your wanting something so wide. Just mash the pedal and heat it up at the start then start feeding. You don't have to rush it. Grinding a flat spot can make it harder to direct the arc at low amperages but again if you mash it and put it where you want it, it will go where you point the end after that. Give it a whirl and post up some pics if ya get a chance

Things that will make your arc spread out wider in A/C mode (and give you a wider, less penetrating bead):
* more EP% (more "cleaning") AC Balance setting
* rounder tungsten shape (think more "balled", not as "sharp")
* longer arc length
* lower AC frequency

Usually, the only applications where I will sometimes purposely want the arc to be spread out wide is for some build-up operations. Then for example you can build up without penetrating and "mixing" very deeply into the parent metals. Usually for joining two pieces together, I will want a more narrow, deeper penetrating arc.

If your weld puddle is slumping it's because you have over penetrated on the the back side, and gravity is taking over on that large molten puddle. With a small enough puddle, surface tension "wins" over the force of gravity (and you can even weld upside-down, for example.) With a large enough puddle, gravity will eventually win over and pull the puddle downwards. You may be overheating the piece of metal you are welding on if the puddle is growing too big. If that is the case, you need to let it cool down, then weld "hotter and faster". Or, there is nothing wrong with doign some welding, then stopping for a few seconds or maybe even longer, to let the workpiece cool down some, before finishing off the bead. Sometimes that is necessary to maintain puddle control approaching an edge to prevent the puddle from spreading out way too wide.

You could put a piece of copper backing plate tight against the back side of the weld if you wanted to "cheat" a little bit. You could certainly penetrate better while keeping the back side from sagging.

Don't expect to be able to fully penetrate on aluminum with a well-fused backside, while welding from one side only with the A/C TIG welding process. Aluminum just doesn't work that way, usually. If you liquify the material through to the back side, oxides will form on the hot back side, that the A/C arc will not break down. As a result, the puddle will not "wet out" on the back side. If you penetrate through about 90% of the material depth, you can build the bead raised up on the front side a little bit to make up for the lack of penetration, and still achieve decent strength through the weld (notwithstanding loss of heat treatment and cold working from the annealing of the metal.) Welding on both the front and the back sides is best if you don't want any discontinuities on the back side, for A/C TIG welding.

Aluminum certainly doesn't weld like steel does.

okay i guess it was just me expecting something that is not needed. i played with it for a while, is 1/4" -3/8"acceptable on 1/8 butt weld ?i hate typing . here are some pics and links to some vids i made. the links will come later looks like youtube is going to be a little slow this evening. tell me what you think. im not a pro tig welder (got 8 years stick and mig) ive been doing it for about a month or so so be nice or let me have it i dont care. lol
links
http://www.youtube.com/watch?v=EttMdaNLGZg
http://www.youtube.com/watch?v=2zFcGyWYuys