Help for a newbie

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Hey guys,A friend of mine has a nice Miller inverter TIG machine, but he has done very little aluminum welding.  He's had a class at the local community college but again almost no aluminum.  I know zilch about welding aluminum.We need help.I have some 1/16 aluminum pieces that I need a few welds made on for the car project I'm working on.  The aluminum is all angle and bar stock I bought at the local hardware store.  We don't know what filler size to start with or what tungsten we should be using.Could we get an idea what we should be using as we start our practice?  It would be helpful to get some starting points:Welder waveform settings for this basic aluminumtungsten size and typeargon flow ratepre and post flow settingsfrequency starting pointfiller rod size and typeI'm sorry to ask such beginner questions but honestly I don't know who to ask, and you guys absolutely know what you're doing!Thank you for any help you can pass along!Hobart Stickmate LX AC/DC, Millermatic 252 & 30A spoolgun, Thermal Arc 185 TIG, Miller BWESmith Oxy-AcBridgeport 2J , South Bend 42" 9AHusky 7.5 HP 22.3 CFM 80 gal compressor
Reply:If it's a Dynasty you will set the welder to AC.  For 1/16 start around 80 amps and the balance around mid point.  Do some practice beads and adjust from there.  If he has the DX model you can play with the pulser and see if that helps.  If his welder is a Maxstar you might get away with running electrode positive with a 1/8 tungsten.DennisThermal Arc 185-TSWMillermatic Challenger 172VictorO/AAtlas Craftsman 12 by 24 LatheEsab PCM-875Wholesalem Tool Mill-Drill
Reply:Good question, I don't know what machine model he has but I'll find out and edit my post once I see him later today.  Thanks!Hobart Stickmate LX AC/DC, Millermatic 252 & 30A spoolgun, Thermal Arc 185 TIG, Miller BWESmith Oxy-AcBridgeport 2J , South Bend 42" 9AHusky 7.5 HP 22.3 CFM 80 gal compressor
Reply:it would realy help to know what welder you are using. as for pre & post flow.pre only needs to be enough to purge the lines so you have good gas flow at the start of the arc, about .5 sec. should be fine for a 12-15ft torch hose maybe up to 1 sec for a 25 ft. hose.post flow is generaly set at 1 sec. per 10 amps of welding curent. 80 amps =8sec. although you might want to increase a lil bit with SS. and be shore not to lift the torch at the end of the weld till the post flow is done, or atleast mostly done, dont let off on the amps and just pull away. also aluminum is big on cratering at the end so drop off on the amps and add an extra dab befor stoping. keep in mind aluminum looks like a good weld when its not so if you are going to put it on a car be shore to do a lot of bead testing befor deciding its good to go. a cold weld can look real nice to a beginer and not hold well at all be shore you can tell the diference befor you start doing any thin that could efect safty of the car or the person in it.cleaning is verry important, always use SS wire brushes and only use them on aluminum only dont go back and forth between steel and aluminum with any of the cleaning/preping suplies, you can carrie small metal partical back to the aluminum work and it will not be prety.i have found aluminum to start out much better if you hit it with the SS wire brush just befor starting the weld. it breaks up the oxidation layer just long enough to get started.depending on how long you have to practice befor you need the parts you might want to just tack the parts and take them to be welded if safty is involved.good luck. be shore to show us your project, we love pic's. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:I'd go with:a/c (of course)200 hz70% penetration3/32 tungsten sharpened normally1/16 filler, 4043 I thinklots of practice - John
Reply:another thing to find out is what type aluminum and the aplication. this could make a big difference in the filler choice.4XXX is softer then 5XXX so its some thing to consider depending on the aplication, is flexing involved ?? what kind of force will be aplied to the finished part?? will it get anidized after you are done ??5XXX would be a beter choice if its to be anidized. summer is here, plant a tree for mother earth. if you dont have time or space, sponcer some one else to plant one for you.feel free to shoot me a PM or e-mail me at [email][email protected] i got lots of time.
Reply:OK, I just heard from my friend with the welder.  It's a Miller Dynasty 200 DX.When he tried earlier, he admitted he didn't know what pre or post flow settings to use.  We were able to fuse parts together but we made about as much slag as anything.  We went with strong as finesse was not possible (yet).As for which aluminum alloy, I could not find any markings on it and the hardware store (Menards) is clueless.  According to the sticker the supplier is Steelworks but there was no indication what alloy this is.  My assumption is that this is basic 6061.The application is a bracket for my transmission oil cooler and aftermarket A/C condenser for an old Camaro.  I could easily MIG this myself out of steel, but aluminum is so much lighter...If you want to see the slop we've made so far, here ya go:Hobart Stickmate LX AC/DC, Millermatic 252 & 30A spoolgun, Thermal Arc 185 TIG, Miller BWESmith Oxy-AcBridgeport 2J , South Bend 42" 9AHusky 7.5 HP 22.3 CFM 80 gal compressor