AC Tig problem...

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Guys, I have a friend with an old Lincoln idealarc tig 250.  Well I do a good bit of work for him, and he basically gave me a blank check to get what I needed to get it set up to be ready to tig if I need it while I'm working at his place.  The machine has been used as a stick machine for years, but not in the tig mode.  Well I get everything hooked up, and decided to give it a test run.  in DC rode it did great, however when I went to AC to play with aluminum I started having trouble.  it would melt a puddle, and I was able to run a bead, but the puddle acts weird.  it's not a nice smooth puddle.  Not sure really how to describe it, but the puddle acts like it has a super strong arc force that is making the puddle pulse I guess, and once you do get it started and try to feed in the filler rod the tip of the rod will melt off, and be blown ahead of the puddle.  Oh, and argon pressure is at 20psi.  I'm not much of a tig hand so I thought some of you might could give me some things to look at.  It has to be something HI-freq related as I have an older hi-freq box that is doing the identical thing that I haven't used in a couple years.  Thanks for any help you can offer.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Does it have an AC frequency control?  Or does it have a balance control?  Either could cause an issue if turned to extreme. Particularly the balance because either pure neg or pure positive may be emitted. Along that line,  I guess a rectifier could be fried and emitting a straight DC neg or straight DC pos.  I dunno, Check the diodes?Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:What diameter filler? 1/16" gives me a headache. It will melt before it gets to the puddle. The biggest improvement I made on alum, was switching to 3/32" filler. It has more mass and will handle the heat better (ahead of the puddle). Another issue I have, if I don't pay attention, I'll let my torch lay down too much, pushing the heat out to melt my filler, ahead of the puddle.  I use as steep a torch angle as possible. Stickout is more sensitive on alum also, less is better. You don't need to see the tungsten, just the puddle. As was brought to my attention earlier; removing the oxides with a clean stainless brush will help.  Good luck, alum can be a pain, but satisfying when learned. Then it will turn on you and kick ya in the shins. 9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Oh, and argon pressure is at 20psi
Reply:Take another look at the argon flow rate.  Flow rate is commonly expressed in cubic feet per hour (CFH).  You stated the argon pressure is 20 psi (pounds per square inch), so I don't think you know what your flow rate is yet.  Do you have a flow meter, or are you just using a pressure regulator?  If you are just using a regulator, then 20 psi is most likely a HUGE flow and the cause of your problem.One type of flow meter looks like a simple pressure regulator but have a particular orifice size so that changing the pressure changes the flow rate in a known amount, and there is a scale on the dial that reads CFH.Another type of flow meter has a floating ball and is very obvious to read.
Reply:I've been welding aluminum for years so I am not new to the process, it's just not what I do day in and day out.  Stick is my main bread and butter so to speak.  I have the machine set with 3/32" red tungsten and using 3/32" filler.  There is no, type of frequency control on this machine, and the aluminum was clean with a stainless brush on  grinder.  I honestly did not think about the regulator.  I use a ball type Flow meter on my tig at my shop, and this machine has a simple regulator.   That definitely could be part of the problem.  I'll take my spare flow meter down there this evening and see if I can get any different results.  Thanks for the help.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:Hammack,I can see you're getting some "help" from real tig "experts".Never seen  AC frequency control on an "older" transformer machine.  Inverters yes.  Transformers no.Your HiFreq has to be working or you wouldn't be able to maintain an arc in AC.Gas flow is the most likely culprit.  Inside, I tend to use about 15-20 CFH. (Argon)Craig also brought up an interesting point.  Too much torch angle will push the heat out ahead of the puddle and make it difficult to feed smaller filler.Tungsten selection for AC and a transformer based machine is also important.  Remember in AC, you're going to have to use a larger tung than you would in DC.  On my Sync 250's (also transformer based) I use mostly the 3/32 and 1/8" Lanthanated tungstens.  Lot of guys like the pure (balled tip), but I've found the lanthanated works well for me.  A ball still forms, but nothing like the size of the pure ball.  Zirconated is also recommended for AC on transformers, but I have little experience with it.Once you get the machine dialed in, you'll want to play with the balance control.  You don't want too much cleaning (indicated by the etch zone by the bead).  All that does is reduce your penetration and add heat to the tungsten.That's a good machine you've got there.  Hope you get her up and running smoothly.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 SundownIIIHammack,I can see you're getting some "help" from real tig "experts"..    ....Gas flow is the most likely culprit. Inside, I tend to use about 15-20 CFH. (Argon)  .
Reply:For aluminum I turn the gas about double for steel.  25 to 35  cfh  I tried it and it works for me.  #8 or 10 gas cone.When I melt off the filler, I point the torch more at the base metal.  The puddle needs gas protection while its cooling and its behind the arc.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:You said the puddle isnt flowing smoothly, is there kind of a dull skin on top of it as opposed to fluid and shiny like it should be?  I see this happen every now and then if my gas flow is to low, or because of the angle im at im not getting proper coverage.  Also sometimes see a greenish tint (in my gold lens) when this happens.I would doubt its an AC balance problem because you can weld at any point in the balance spectrum and not get a weld that acts like you are describing.  Like mentioned not HF problem, because you wouldnt even get a puddle then.Have we all gone mad?
Reply:This torch has been sitting for how many years?Cracked hoses?Real world weldin.  When I grow up I want to be a tig weldor.
Reply:I didn't have time to get down there today to play with it, but the torch and hose is a new one.  I'm getting a clean puddle, no film, just acts erratic.  I will try to make a vid of it tomorrow when I get time to play with it. Maybe then you guys can see what I am talking about.  I am thinking that is could possibly be a gas problem, with the regulator, but I'll see tomorrow for sure and let everyone know.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......