Black goo on rod

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I have some old material, salvaged at no cost buletin board frame 2" wide 1-1/2" deep aluminum shaped like channel with a false bottom leaving a hollow void 1/2 x 1-1/2" at its thinnest it is 1/16th thickest 1/8. It has a heavy oxide layer as it has been stored outside for years. After grinding off the oxide, fitting, and hitting it again with stripper disc from Radnor or Blaze from Norton, I wire brush with clean stainless hand brush. Welding TIG Dialarc 250 HF pure tungsten 1/8" argon it begins to clean, wets liquid not quite bridging the gap. Then I touch the rod everything goes bad. A ball forms, gets dirty, drips off the tip of the rod, rolls around, black goo comes out of the joint. With persistence I sneak in from the side of the puddle, dab filler and weld. Not perfect, not ugly. How thick might anodizing be? Are there varieties of aluminum probably extruded that don't lend themselves to being welded? Am I doing something wrong? I've tried 3 different types of rod.Bill
Reply:Originally Posted by Willie B. Then I touch the rod everything goes bad. A ball forms, gets dirty, drips off the tip of the rod, rolls around, black goo comes out of the joint.  Am I doing something wrong? I've tried 3 different types of rod.Bill
Reply:Ok forget Bistineau and his Tom Foolery, useless comment. Here's the deal. If you and two of your friends are having the same problem, try a different girl! I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:Grinding dirty aluminum can embed (smear) the crap into the aluminum. Same for a flap disk on dirty alum.Settings?Amps, shielding cfh, filler rod type and size?Are you forming a puddle in 3 seconds or less? It sounds like you are slowly heating and then adding rod before you should.What happens when you weld on nice clean material?Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Dave, i can see those two other guys are getting a head start on the Christmas party. Perhaps they have to spend time with extended family or even (God forbid) inlaws, and can't face it sober. Nonetheless, no I can't get this aluminum hot enough in three seconds. Should I crank up enough to clean & puddle sooner? It's a big machine, but going even hotter I hadn't tried, as is 1/8" pure tungsten balls up more than I want it to. Should I try thoriated? I'm a little shy of it if it is radioactive. No, I'm not having the problem with new aluminum. It is significantly better with freshly ground tungsten, as it begins to ball up the problem begins. I dip too often, but this is before contaminating electrode.
Reply:You still have not answered the set-up questions so I can't tell you to go hotter or not.Set-up to get you in the ball park:#7 or 8 cup15 to 20 cfh 100% argonTungsten stick-out less than cup inner diameter150 amps for 1/8" aluminum and hit the pedal quick, puddle in <3 seconds1/8 pure, 2% thoriated or 2% lanthanated ground to a fairly blunt taper and a small flat spot, let it ball as you weld.3/32 filler rod of your choice, insert into the puddle at a low angle when possible and only when there is a clearly defined puddleIf you can't get the filler into the puddle before it balls up and melts off, your technique is wrong, watch Jody at welding-tv.com for some excellent tips and clear video.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:#8 cup, 20CFH Argon, Tungsten 1/2 of cup diameter, Was using pure 1/8" long taper it would ball up larger than electrode diameter. I've been trying Thoriated 2% with some success it seems to splinter, but works better than pure without ball up. I've been working on a very tight arc, and backstepping technique. It still doesn't seem to get dirty until I dip the rod. If I introduce rod (1/8") at center of gap, black comes out of joint. If it comes in from one side it flows well. I'm suspicious shielding gas isn't getting into the gap. Mostly it's square stock against square stock, I think fit up may be too tight. Where fit isn't as perfect I don't have the problem. As for heat the Dialarc 250 is at the highest range, the dial 1/3 from low. I step hard on the pedal first ten seconds, then feather off as workpiece gets hot. With thoriated the arc is narrower, concentrating the heat, in a few seconds it now looks liquid in a 1/4" dot in each surface. Much faster, much cleaner. I have avoided Thoriated until now, how radioactive it is I wouldn't understand if you told me. When I was a child MIT did an experiment trapping thousands of chipmunks, injecting them with a radioactive liquid. First year thousands of chipmunks a day, second year maybe a hundred a day, third year no chipmunks. 45 years later 2000 acres without a chipmunk to be found. Draw your own conclusion, MIT swept it under the rug, they now deny it ever happened. I was there many days, it happened. Is thorium only mildly radioactive? It occurs to me the safety experts wouldn't allow it to be sold if it was very dangerous. Then again, I can buy cigarretts, booze and in most states marajuanna.Thanks so much for your help!Oh, some uninformed are more dangerous when they think.
Reply:Without welding them together, can you bead one piece without contamination?1/8" stock needs no gap, use amps to penetrate. There should be a distinct bead on the back when you are done.Using the same size filler rod as the metal you are welding can chill the puddle too much with each dip - I've only welded up to 1/4" alum so far, but still used the 3/32 rod and just fed faster. (Have lots of it)I've only been on tig for about 2 years with occasional use. I use stick and mig more. Pics of your beads will usually get more help from the others here Edit: I've seen different Dialarc ranges, what is the amp range you are using?Last edited by MinnesotaDave; 12-23-2013 at 09:34 PM.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I wish I could slow one of the computer geeks in my family long enough to show me how to send a sketch or photo. The cross section of this material is complex, at the back run two L shaped grooves, these back up to a hollow rectangle, then a channel. The void, and the grooves being particularly tough to clean out. I think I'm getting contamination. If I clean weld surfaces then handle, crud falls out of these voids contaminating everything just cleaned. I think I'm going to use this material up on something I don't have to weld. Whether I clean or don't I can run a bead on a flat surface of this product. The Devil lies in joining pieces together.I'm running on 125-310 Amp with dial set at 40 heat seems OK as I can back off on foot pedal. What I'm reading suggests it is desireable to ball even thoriated tungsten using DCEP, I haven't tried yet. The pin point arc with un balled electrode works well. As I log more hours with this antique I become more confident, I am considering an upgrade to a Dynasty, a big financial extravagance as It doesn't earn my living. Wondering if a spool gun for my MM252 MIG would be a better option. My experience with spool gun is minimal. It might prove a good choice for 1/4" range material, (truck bodies etc.)
Reply:Sounds like you've found the problem - dirty crappy used material.I don't take the time to ball the tungsten as I know it will ball on its own. Blunt pencil taper, then a small flat on the tip, weld.Your Dialarc will handle 1/4" material and you'll find it easier than thin stuff. Spool guns are fast - I just don't like them as much. Almost never use mine. No truck bodies for me to weld laying around Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
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Reply:Maybe a non weldable alloy ? ?
Reply:Originally Posted by PavinsteelmanMaybe a non weldable alloy ? ?
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