Any professionals on thin aluminum? (TIG)

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I'd like to be able to do radiator and intercooler repair, so I am trying to practice welding some super thin aluminum with my Dynasty. I didn't have any empty beer cans, so I tried a disposable pie pan. It mics at .004" thick, It's very soft and shiny so I'm guessing it might be 1100 series. I figure that if I can weld .004", a .015" thick radiator or intercooler should be no problem. I'm picking up a disposable turkey roasting pan next time I'm at the supermarket for more practice material. Whatever alloy they are made from, it seems weldable. It's definitely a challenge!Here's what I've figured out so far:-You have to keep the amps low (duh). Over 7 amps = instant burn through-You have to keep the freqs low, 40hz and lower seems to work well. Over 60Hz = instant burn through.-You have to keep the % balance EN as low as possible, 20%EN-80%EP seems decent. Over 90% EP I had a lot of trouble starting an arc and my tungsten looked like it was about to melt off.  Under about 65% EP It's putting too much heat into the work = instant burn through.Here's what I could use some help figuring out:-Should I disregard the fact I'm welding at 5 amps and use a larger tungsten to prevent balling? (I'm using .040" ceriated) I never balled a ceriated electrode before I tried this project, but I'm abusing the hell out of it with all the EP I have to dial in to keep the penetration low. Should I forget what the manual says for inverter machines and just run a green tungsten balled?-I can get a stringer bead going once the arc is stable, but I seem to be having a problem with "inrush current" at start. I get a big burnout hole, then I can get a bead going. It's the total opposite of welding thick aluminum. -Should I try starting the arc on a copper plate and then running onto the work? I think it may be because The welder starts the arc at full current (5 amps) and then the electronics look to see where my pedal is. Which leads to my next question...-Is the 5amp minimum on AC literally 5 amps? My pedal position seem to reduce the current after the arc starts. I don't know whether I'm getting over 5 amps and it's dropping to the minimum of 5, or I'm getting 5 at start and it's dropping to something under 5. I never thought about this stuff until now. Minimum ratings are usually given by the manufacturers for bragging rights - how many people actually weld at them?-Is this even possible without a heat sink? There's people welding beer cans with old synchrowaves, so there's got to be a trick I'm missing somewhere.-Matt------------------------------------------
Reply:Which Dynasty do you have? I know on our 300 you can adjust the start amperage and polarity, I don't know if it goes below 5 amps though.Yup
Reply:The 'trick' that many use when welding beer cans etc is to strike an arc on the filler rather than the base metal. My v205t has a low of 5A but with pulse on the background minimum is 1A- average of around 3A. Never used a tungsten below 1/16. Beer cans can be welded with various different sized tungstens and filler- it's actually easier with 3/32 filler and 25A or so IMORad and intercooler work doesn't get anywhere near that thin. The cores are supplied with a mounting flange for the tanks to be attached to which is typically around 1 to 1.6mm (0.040 - 0.065") for rads, sometimes even thicker for intercoolers due to the pressures. Remember, these things are designed to transfer heat- the last rad i made had 1.6mm flanges, 2mm tanks (due to their size) and i was running around 120A initially.If you're talking about fixing leaking tubes then things get dicey but not for the reasons you'd think. Tubes are delicate but you still need to throw a bunch of amps at 'em (heat transfer again) and just be very quick and accurate. TIG is far from the best tool for tube repair as the cores are vacuum brazed brazed construction- contamination, heat is too focused etc. 4047 is a brazing alloy but not with TIG, strictly speaking
Reply:Originally Posted by hotrodderThe 'trick' that many use when welding beer cans etc is to strike an arc on the filler rather than the base metal. My v205t has a low of 5A but with pulse on the background minimum is 1A- average of around 3A. Never used a tungsten below 1/16. Beer cans can be welded with various different sized tungstens and filler- it's actually easier with 3/32 filler and 25A or so IMO
Reply:Originally Posted by hotrodderThe 'trick' that many use when welding beer cans etc is to strike an arc on the filler rather than the base metal. My v205t has a low of 5A but with pulse on the background minimum is 1A- average of around 3A. Never used a tungsten below 1/16. Beer cans can be welded with various different sized tungstens and filler- it's actually easier with 3/32 filler and 25A or so IMORad and intercooler work doesn't get anywhere near that thin. The cores are supplied with a mounting flange for the tanks to be attached to which is typically around 1 to 1.6mm (0.040 - 0.065") for rads, sometimes even thicker for intercoolers due to the pressures. Remember, these things are designed to transfer heat- the last rad i made had 1.6mm flanges, 2mm tanks (due to their size) and i was running around 120A initially.If you're talking about fixing leaking tubes then things get dicey but not for the reasons you'd think. Tubes are delicate but you still need to throw a bunch of amps at 'em (heat transfer again) and just be very quick and accurate. TIG is far from the best tool for tube repair as the cores are vacuum brazed brazed construction- contamination, heat is too focused etc. 4047 is a brazing alloy but not with TIG, strictly speaking
Reply:You may want to purge and flood the rad, intercooler with argon.
Reply:Another thing is your presure build up on argon gas on start on the weld area. If you dont have a two stage flow regulator,you might be putting too much presure at start causing a blow through.H1400 smith's regulator is the way to go!
Reply:Try welding it on DC+, I havent played around with any really thin aluminum (<.040) but I think this would be a great way of doing it.Have we all gone mad?
Reply:Not to be blunt, but.If you plan to build your radiators/coolers out of pie pans, ok.  Keep screwing around with the pans.Personally, I'd suggest getting your hands on some of the "actual material" you plan to use and do your practice/dialing in the machine on that.You've got no idea what crap went into that pie pan.  About as useful as welding razor blades together.Sorry, just the way I look at things.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 sn0border88Try welding it on DC+, I havent played around with any really thin aluminum (<.040) but I think this would be a great way of doing it.
Reply:Originally Posted by RojodiabloIt won't have any cleaning action, and the DirectCurrent part of the DC thing will burn right through thin material.....
Reply:Originally Posted by SundownIIINot to be blunt, but.If you plan to build your radiators/coolers out of pie pans, ok.  Keep screwing around with the pans.Personally, I'd suggest getting your hands on some of the "actual material" you plan to use and do your practice/dialing in the machine on that.You've got no idea what crap went into that pie pan.  About as useful as welding razor blades together.Sorry, just the way I look at things.
Reply:It's been almost a year, if Hephaestus hasn't got thin Al figured out by now he probably never will. Might well be up to his neck in rads right now as he's not posted since JanAre you guys seeing many epoxy rads? Ignoring the OE style rads with crimped plastic tanks pretty much everything over here is vacuum brazed, there were some cheap ones doing the rounds a few years ago but they quickly gained a bad rep. The latest batch of cheap ones seem OK- imported from the States (don't know if they're made there) as a 'kit' needing the inlet/outlet, bleed/cap letting in and mounts finalising. Far from the ideal way but cheaper than an equivilent core in the UK