TIG welding aluminum turning black and blobbing

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I have been trying to weld plain mill finish 6061/6063 aluminum angles together. Prior to welding I use a file or stainless steel wire brush to clean around weld area. Shortly after initiating the arc, the joint that I am trying to weld turns black with soot. If I continue with the arc the aluminum anlge at the joint will blob up, and fill with porosity embedded with black soot, this get worse if I try to add filler wire. I Then use a die-grinder with a burr to remove remove the mess and retry. What is going on here? The supplier claims that the aluminum is plain and not anodized. I have welded aluminum with success before, this has me stumped. My welder is a MILLER Syncrowave 180 SD. I am using Argon gas at 30 CFH. The filler I use is either 4043 or 5356. Any assistance here would be great help, my project is starting to look pretty ugly.
Reply:the only thing that equalls black soot is contamination...the puddle "balls up" because of it..its not really "melting" into a puddle rather its just "floating" around on top of it...your tungestion could be the culprit right off the bat...are you grinding it on a stone for tungestion ONLY?acetone everything before you start...front back sides underneeth.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Sounds to me like the machine is still on DC .....did you switch the machine over to AC?http://all-a-cart.comWelding Cart Kits and accessories
Reply:Originally Posted by ZTFabSounds to me like the machine is still on DC .....did you switch the machine over to AC?
Reply:Ha...I only know because I've done it. After balling my tungsten with DCEP, I've accidentaly left it there and...whoops!!!!   http://all-a-cart.comWelding Cart Kits and accessories
Reply:Black soot and porosity, couldn't those be symptoms of a gas problem?
Reply:I think Joe H is probably right.  It is very rare but I have got contaminated argon from time to time.  Sometimes the dealer will fill your bottle from a battery of bottles and if they don't purge the lines properly, you can get bad gas.  One time by mistake I was given a mixture which I immediately took back.
Reply:Joe and Riley...that is a definite possibility. One of the reasons I suggested that it may the wrong setting is that jtweld didn't mention that he tried changing bottles...I ASSumed that he has welded with his current bottle of gas.I too have received "bad" gas...and boy was I mad!  It was a couple of years ago. I had just exchanged my only bottle for argon on a Friday at closing time (for Airgas not for me, I'm self employed!!!) got back to my shop to finish welding a roll cage...and  !!!http://all-a-cart.comWelding Cart Kits and accessories
Reply:I have even forgotten to open the tank valve before. Took me WAAAAAAY too long to figure it out too. I blame the beer.
Reply:30 on the gas seems kind of high. I am assuming you are using pure argon. Sounds like the gas is hitting the work and then oxygen is getting swirled in because of the high velocity of the gas. Try turning it down to 17. Note this is after you have checked all of the above. Please give us some more information on the machine settings. I had a 180SD and it was a great machine to learn on.Thanks.  T.J.
Reply:Originally Posted by TJS30 on the gas seems kind of high. I am assuming you are using pure argon. Sounds like the gas is hitting the work and then oxygen is getting swirled in because of the high velocity of the gas. Try turning it down to 17. Note this is after you have checked all of the above. Please give us some more information on the machine settings. I had a 180SD and it was a great machine to learn on.Thanks.  T.J.
Reply:Thanks for all of your input. Had Our Miller rep stop by Wednesday, we found that the fitting for the gas/power cable inside the torch body was slightly loose; which could draw in air, thus contaminating the gas (good call on that). This also explains why it would weld good at times, because of the depending on the position it is held it could leak or not.Remember, today is the tomorrow you worried about yesterday - Dale Carnegie
Reply:Use an Oxy-Acetylene torch rig with an Arc Welding Rod (Alum#43) from your local welders supply & Braze it, the results are awsome, before you weld/braze clean the aluminum with Easy Off then clean it again with Isopropyl Alcohol then clean with a stainless steel brush, also preheat the area with a propane torch for about 5 min. when the metal is hot enough there will be a greyish spot test your stick & braze, feather your torch on the weld and the stick & don't overheat, cleanup cooked on flux from the stick with light sanding, spray aluminum to reseal the welded area & you're done.  ..... Tig is nice, but for Aluminum it has to have an A/C output, .... Brazing it in this manner is just easy.
Reply:Hmmmmmmmm I read your post and you never mentioned you serviced your tungsten after the black soot and balling happened.....I assume the reason your argon was so high was because you were trying to cover up the unknown air leak?Last edited by B_C; 01-28-2014 at 11:33 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Too bad it is a bull$hit definition. If you have a loose fitting on your garden hose does it suck in air? No, it blows out water. Same thing is happening here. This is a positive pressure system not a negative pressure system. If you have a leak, your gas leaks out, not in. So the truth of the matter is that you were loosing you shielding gas before it got to your torch.
Reply:And then BC comes on and posts the standard that few of us will reach. Beautiful welds!
Reply:Originally Posted by walkerToo bad it is a bull$hit definition. If you have a loose fitting on your garden hose does it suck in air? No, it blows out water. Same thing is happening here. This is a positive pressure system not a negative pressure system. If you have a leak, your gas leaks out, not in. So the truth of the matter is that you were loosing you shielding gas before it got to your torch.
Reply:The brazer gets the miner award for digging up a 7 year old thread! Beautiful beads there BC. Miller Dynasty 200DXMiller 252 Miller 250xMiller Syncrowave 250Miller AEAD200 LegendMiller 375 Xtreme plasmaLincoln WeldPak 100Victor O/A