A few n00b questions (Tigging aluminum)

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So I picked up the machine, tried it out and realized that I needed some other supplies (proper gas, more tungsten, different filler rod types).  I got those things and have had much better luck with it!  So here is round 2 of the questions - When TIG welding, it almost seems as though it's more important to fit things really  well because you have to make a pool from two different pieces of material.  When MIG welding, you can fill some amount of gap pretty easily.  Does this seem to be a vaild observation?  Is there a standard was of jigging things so they stay in place before they are actually welded?  Steel is easy because you can use magnets.  What about aluminum?  I'm currently working with 1/8" aluminum.  Do I need to bevel the edge at all?  I wouldn't think so, since that's pretty thin.  But how about when I'm trying to butt together two pieces at a 90* angle?  How should I prep the edge in that case?  What I'm seeing is that the material seems to try and pool up, but the pieces kinda pull away when that happens, too.  And a really basic one...  When the base material begins to pool, when do you begin adding the filler?  It seems as though the filler is too cool if it's not in close to the arc, and sometimes it'll ball up at first instead of flowing.  This one might just be a practice thing, so don't feel bad about saying, "You stink, kid!"  hahaThanksLast edited by MikeSVO; 11-17-2006 at 10:20 AM.
Reply:I think you have the right idea.  A tight fit-up, with clean square edges, makes it easier for the melted areas of the two pieces to coalesce and wet together.  A dab of filler, added at the right time, helps bridge the separate melted areas and form a single pool.For most anything, even if it is jigged up well, tack welding in a few key places is the way to set things up for welding.The question of beveling 1/8" aluminum.  It depends on how much penetration you need and how much penetration you can achieve with your power supply and your welding technique.  If it has to be full penetration and your not getting it, then look at beveling.In making the fillet weld on a 1/8" aluminum "Tee" joint.  you should first put at least two tack welds at the ends, assuming this is like a 6" long practice piece, if its longer then more tacks.  You'll need to dab a bit of filler to get the tacks in there.  Then same thing when you start the weld, start the arc, get a bit of melting on each side of the joint, then quickly deposit some filler to get the pool started.As you suggest, I think it takes some finesse to get that first dab of filler in there to form the pool.  If you wait too long before adding filler, the pieces melt away from each other leaving a hole.  If you add filler too soon, it balls up on the surface and doesn't wet out to the joint.  It's a delicate balance.  I think part of the deal with aluminum is to get in there with plenty of current and don't piddle around, melt, add filler and go.
Reply:The keys to jigging an aluminum joint in place are clamps, angle plates, and good tacks.  Also, if your filler wire is balling up, you might have the wrong torch angle.  Try putting your torch at more of a 90 degree angle.
Reply:Thanks a bunch, I'll try that out and see how it does!
Reply:You didn't mention the wire size you are using.It may also help to use a smaller size filler wire. If your wire is too large you can have trouble with the end balling up. Washman
Reply:The guy at the supply store I go to said to use the stuff that was about 1/8", and while I was surpised at that since it seems hefty, it does get consumed quite quickly.  I asked about thinner stuff, and he kinda discouraged it, but still threw in a few rods for me to try with.  Those were about 3/32" or 1/16".
Reply:1/8th? thats way too big to start..go with 1/16 and feed it faster..you'll see.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.