fillet weld trouble

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So I just got my new miller home and ran a bunch of beads on some 1/4 alum. Its freakin awesome. Just tryin to get acquainted with the settings and the pedal. So ok it was time for a joint. A t joint lol. Tacked up and then I started did a one inch weld and it was perfect. Super even....ripples were beautiful. I was impressed. So I lit back up and blah I couldnt get the metal to wet...I went to the other end same thing perfect. So I went back to the middle...blah crap. I need some tips on torch angle and where exactly to point the tungsten in the joint. Never had this problem before....alum was scotch brited with a die grinder then acetoned. I welded. On the top edge of the t it was perfect too. On a horizontal butt joint it I welded perfect again. I think im just using the wrong torch angle or something of that nature on the t joint fillet. Using 210 amps balance 70% 3/32 cer 3/32 filler no pics right now but maybe somone  can post a pic of their torch in the joint. ThanksMiller Syncrowave 210 w/CK FlexLoc 150  3/6/14ESAB PCM 1125 Plasma CutterAtlas 12x36 LatheACER 9x42 3hp millHarig 612 Surface GrinderDRINK Machine              welding&fabrication
Reply:Sounds like you might need more amps, the edges weld because it doesn't remove the heat from the puddle as fast. What size cup and CFH did you use? Too much flow will cause trouble welding aluminum. Keep the torch almost 90deg to the joint, just a little push angle.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:8 cup with lens and about 17cfh. At the other end I started same direction but I was about an inch and a half from the end. 7in long joint. And it welded fine. But lighting up in the center it was crap it can be done....weldermike has the same welder and I seen his t joint nicely done but it m8ght have been 3/16 alum instead of 1/4Miller Syncrowave 210 w/CK FlexLoc 150  3/6/14ESAB PCM 1125 Plasma CutterAtlas 12x36 LatheACER 9x42 3hp millHarig 612 Surface GrinderDRINK Machine              welding&fabrication
Reply:Can you describe what it actually did when you tried to start a bead in the center? Black and sooty- Erratic arc- Loud arc- Popping from puddle- Won't form a puddle? Did you have the pedal down all the way so you had full amperage? If you have more aluminum try wire brushing and using acetone to clean, maybe the scotchbrite isn't cleaning enough? Lots of things will cause problems.  Turn your CFH down some and see if it helps, keep lowering it until it either welds like it should or you get porosity. Flowmeters can be wrong.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Yeah it was full amps. And a die grinder with roloc scotch brites is plenty to clean the surface..that what I use to remove rust from the underside of a car....if I pointed the tung at each side of the joint it would start to puddle but it wouldnt puddle enough to get both pieces wet so I could add filler....I didnt want to camp forever on that one areaMiller Syncrowave 210 w/CK FlexLoc 150  3/6/14ESAB PCM 1125 Plasma CutterAtlas 12x36 LatheACER 9x42 3hp millHarig 612 Surface GrinderDRINK Machine              welding&fabrication
Reply:Chevy: puddle one piece at a time then dab your filler a couple times join the two pieces together and weld on. When tacking aluminum the arc tends to favor one side over the other.
Reply:Ill try out the suggestions and report backMiller Syncrowave 210 w/CK FlexLoc 150  3/6/14ESAB PCM 1125 Plasma CutterAtlas 12x36 LatheACER 9x42 3hp millHarig 612 Surface GrinderDRINK Machine              welding&fabrication
Reply:So what is the follow up?  I am having similar problems and am looking for a solution.
Reply:Heartdoc you need to post more info if we are going to help. 210 amps is low for 1/4". Even cranking up the hertz and upping the balance still leaves 1/4" at the very end of the possible spectrum if everything is perfect at that amp setting.My guess from the limited info would be you need more power. That's typically the issue many times when guys try to weld alum with tig. Alum is such a great heat sink it sucks up way more power than most expect. You can weld 1/8" steel at 100-125 amps, but with alum, you need to be at 150-200 amps to get the puddle to form fast to beat the heat sink quality of the alum..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Mike,Think about a filet.  The oblique cross section of 2-1/4" pieces held together at 90* is somewhere around 3/8" if they are lapped.  Turn your machine up to 280, I'd personally keep the freak low for more umpf, stand on the pedal pointing the arc at the joint angle.  Then move the tungsten vertically side to side a little, then dab some filler.  It's one of the easiest joints because you have somewhere to rest your hand or walk the cup the whole way (not a true walk, just a slide).  For some reason, the initial dip is the toughest.  Once they bridge, it's fairly easy to continue the bead towards u.  AlTA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum