Practicing up on aluminum

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All,I TIG weld pretty good on most metals except I don't get a chance to do much aluminum. That may change here in the near future and wanted to get some time in. Welded tonight for a couple of hours. After the third run I started to get it down. I am getting some contamination like I have seen on the website before but can't remember what the source was. The weld is covered in tiny little bumps, almost like the surface of rough sandpaper.I was using alcohol and a scotch brite pad followed by more cleaning under running water. Maybe I need to get away fom the alcohol?The metal is 6061 at .120. Filler is 4043 at 3/32.The machine is a snycro 250 set at 200. I played around with the balance, but didn't see much difference. The tungsten is red and 1/8. I even took a break and welded two cans together. That wasn't that hard. Although it wasn't pretty. I tried small aluminum beads between the cans but that wasn't happening.Can anybody give me advice on getting a nice smooth weld bead?Thank you for any input. Attached Images
Reply:One more picture. Attached Images
Reply:OK, I did some searching on here and found others with the same problem but not a clear cut solution. My plan is to:Get a new larger cup. It is old and dirty and too small.Turn up gas slightly.Try moving along a little faster.Use acteone.A new tungsten ( the one I was using has been used for everything but the one piece was all I had when had the time to practice).I'll post more pictures when I try again.One thing that I found interesting was the soda cans don't seem to have this problem. I was using a brand new 1/16 red tungsten on that.Last edited by patkenbar; 08-08-2012 at 06:32 AM.
Reply:Going too slow and running too few amps will often overheat the material and give you what you are seeing. You have the machine set at 200, but are you really running that hot? That "pimply" look is typical of someone who is running at roughly say 100 amps and going  slow to let the puddle form. Alum likes to get welded hot and fast. Hit it with a lot of amps to get the puddle going fast and fly, backing down as needed to adjust as the plate warms up.Other than that it looks very good..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:The balance knob on a syncro actually doesn't change it all that much. Even though the dial reads from 0 to 10, 0 is actually 45% and 10 is something like 68% (electrode negative). On clean stuff, you can most likely crank it up to 10 with no ill effects. I like to think aluminum takes confidence to weld "pretty". You gotta mash the gas and haul a$$. You joined a pepsi and a coke can. How dare you...
Reply:http://www.weldingtipsandtricks.com/...-training.htmlThis is really good practice for welding aluminum. I been doing this for a couple hours and I'm starting to get the hang of this whole aluminum thing. Monday was the first time I ever ran an aluminum bead, although I have TIGed a good bit of steel before.Brad GeorgeCurrent Equipment:AIRCO Heliwelder IV 300Amp Model - Total Awesomeness!Old 120v Hobart Handler MIGVarious grinders, cutting tools, hammers, clamps, ect..."I'm an amateur welder with lots left to learn..."
Reply:Those bumps are silicon clumps surfacing from overheating.Switch to 5356 and you will get rid of it.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.