Newbie aluminum TIG

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Last week I bought a used Miller Dynasty 200DX to learn how to TIG alum and stainless.  I've got a little experience w/ MIG and O/A but no TIG.  This is just a hobby of mine....no production...just for fun.  The machine came with both foot pedal and torch control wheel.Didn't have any Argon so I tried my MIG mix (75/25 ar/co2)...melted some 1/8" alum plate...blob fell on my nylon tool bag...burned a big hole...lots of smoke...75/25 doesn't work for sh!t...just like I'd read everywhere.  Also broke the gas cup trying to clean out some slag.Got a tank of 100% argon and a gas lens w/ cup and tried again using the settings from the Miller manual for 1/8" aluminum.  First attempt (lap weld) was bright and shiny but looks like way too much heat.  Second try (edge joint) was better but a little ragged on the edges.  Third try came out looking really nice...better hand control and a little more agressive on the foot pedal.  Note that all of this is w/o filler rod.Settings are AC, 140 amps max, 65% balance, 140 hz freq, 3/32" 2% thoriated tungsten, 1/8" tungsten extension beyond the gas cup, 20 cfm argon flow.Question:  I managed to keep the tungsten from touching the puddle but I'm seeing tiny little beebee's on the tip (see photo).  Is this normal or, if not, what causes this? Attached Images
Reply:Wow I'm impressed for first tries. Yeah 75/25 doesn't work too good ha.When I first got my tig the LWS gave me the wrong tank. Since the machine was brand new it took me a while trying to figure out if it was settings or something wrong or what. Finally figured out what happened. Also learned a valuable lesson. Always look at the bottle before you leave the store haha.With AC some deformation of the tungston is pretty normal. Thoriated isn't really ideal and can tend to split. Others are not designed for AC either. I just started using lanthanated tungsten. I really like it. It does both AC and DC very well and it's not radioactive like the thoriated. If you just want one for everything it's a good option.Lanthanated and other good AC tungstons will ball up on the end.Last edited by yoshimitsuspeed; 12-31-2009 at 10:16 PM.Lincoln precision TIG 275Millermatic 140 MIG
Reply:Alum really needs filler to prevent joint cracking. You would be best off starting on steel. It's easier to see whats going on and happening doing steel than alum. Once you get control of the heat down, adding filler and so on, then move on to alum. Trying to do all this at once is just making it hard on yourself and making it difficult to see where your real problems lie. It's real tough to try and help someone trying to do a "T" joint in alum when they can't focus the heat on the right place on the plates and adjust the pedal as the upper plate heats up and then starts to melt too much. Alum where you can't see the change as much just makes this really tough..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:Originally Posted by DSWAlum really needs filler to prevent joint cracking.
Reply:Lanthinated! I swear, thoriated is a magnet for contamination with alum. (and that is all I used to use.) Ceriated works well too. And where did the cracking issue come in? You can successfully weld alum .without filler.Last edited by papabear; 12-31-2009 at 11:58 PM."SOUTHPAW" A wise person learns from another persons mistakes;A smart person learns from their own mistakes;But, a stupid person.............never learns.
Reply:Originally Posted by papabearLanthinated! I swear, thoriated is a magnet for contamination with alum. (and that is all I used to use.) Ceriated works well too. And where did the cracking issue come in? You can successfully weld alum .without filler.
Reply:Not saying your wrong Rojo, just saying you can successfully weld alum. w/o filler. This is non-structural A356 alum. casting rejects welded together w/o filler. I know there are types of alum. that are considered non-weldable. Attached Images"SOUTHPAW" A wise person learns from another persons mistakes;A smart person learns from their own mistakes;But, a stupid person.............never learns.
Reply:That looks good Papabear. I think by the design, you will have a better chance of success without filler, as the chance for flex and tear is looking to be non-existant. You could not get away with that on a typical T joint, but for that application, and material, you are probably dead right. Thanks for showing that there is always more than one way to skin a cat!!And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:It would have been stronger if filler had been added.Rojo,Just for clarification.  Transformer based tig welders are not "regulated" to operate at about 65HZ.  Transformer based welders operate at 60 HZ (Cycles) because thats the frequency the power grid, in the United States, provides.  In Germany, for instance, they operate at 50 HZ (cycles) because thats what the grid provides.Transformer based welders have no capability to vary the HZ (frequency) like the inverters.Squarewave machines make the transition from DC+ to DC- faster than the older sine wave machines, but they still operate at 60 cycles per second.  Balance allows the operator to vary the time the machine spends in each half of the cycle, but does not affect the HZ/cycles.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Originally Posted by SundownIIIIt would have been stronger if filler had been added.
Reply:well, I would have gound a chamfer around that cast piece.  then filled the groove with filler.  then it wouldnt be ground away.    I would not even have considered just matching them flush and buzzing around them....but you sure did a mighty clean job of it.  it looks great!