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  1. #1
    Join Date
    Feb 2012
    Highland, Ca

    Default Am i experiencing a contamination issue? or Something else

    I just started welding not too long ago, and up until now ive only been learing to weld aluminum plate and so far i think im getting the hang or it. So i wanted to try out some aluminum piping. At my local srcap yard i found a bunch of 3" diameter x 3foot @ 1/16" thick Aluminum piping in their 6061 section.

    Im having a real hard time trying to weld this stuff. everytime i make a puddle and start moving i can see a bunch of crap floating on the top of the puddle. this happens even after i hit it with a stainless steel brush real good. Maybe this stuff is annodized??? Or maybe a weird alloy? Anyone have any pointers for thin Al pipe.

    Settings on Syncrowave 250
    High frequency always on @ 70
    3/32" 2% thoriated
    100% argon @ 15CFM

    Here are some pics.

  2. #2
    Join Date
    Dec 2007


    I would try just running a bead without using any filler.
    In other words, start a puddle and then move it along the pipe.
    If bead looks ok, then add the filler and see.

    I had similar problems. I could run a clean bead alone but I got "pepper flakes" in the puddle when I started adding filler.

    Found out that my filler rod was contaminated so I cleaned it using a scotchbrite pad and wiped it with acetone. Clipped the end of the rod before starting a weld.

    Your flat pieces look good so it may be the pipe material.
    Thermal Arc GTSW400, Airco Heliwelder II, Miller Dynasty 350, Hypertherm 1000, oxy-fuel setup, metal cutting bandsaw, air compressor, drill press, etc.:

    Call me the "Clouseau" of welding !

  3. #3
    Join Date
    Mar 2007
    Deltaville, VA


    Have you even read the owner's manual that comes with the Sync 250?

    In your photos you show a balance setting of 2, 4, 6. You're putting way too much heat into the tungsten (too much DC+) and not enough heat into the workpiece (DC-). I normally run my Sync 250 at a balance setting of between 7.5 and 8.5.

    Some will disagree, but I don't like thoriated tungsten for welding in AC. I prefer a 2% lanthanated or ceriated. If you like the ball produced by pure, the zirconiated tungsten will still ball but will handle the amps better than pure.

    Why do people feel the need to jump right into tig welding aluminum before they even master the basics with mild steel. You'll find that those steps you just jumped over will come back and bite you in the azz.

    The Miller Tig Handbook (available under the Resources tab above) should be required reading for anyone starting to learn to tig weld.

    PS The HF control you refer to is simply an "intensity control" which sets how strong the HF is. A setting of 7 seems high to me (been awhile since I had a Sync with the intensity control--been eliminated on the newer machines). You want it set just high enough to insure reliable arc starts. Too high and your wife/neighbors will be yelling at you for screwing up their TV's or computers.
    Syncrowave 250 DX Tigrunner
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    Miller XMT 304 w/714D Feeder & Optima Control
    Miller MM 251 w/Q300 & 30A SG
    Hobart HH187
    Dialarc 250 AC/DC
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    Wilton 7"x12" bandsaw
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    Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
    Thermco and Smith (2) Gas Mixers
    More grinders than hands

  4. #4
    Join Date
    Feb 2012
    Highland, Ca


    AC balance settings in the pics were 2,6,9... I've always had it around 7-8 and got good results welding 6061 plate. I was trying to lower it so i could see if it would "clean" the surface and produce a different/better weld.

    Ive read my manual and most of the tech articles miller has online regarding TIG. But still some things dont quite make sense yet. like, the AC balance, yes i get that when the AC balance is high @ 8.5 your getting all of penetration because alot of heat in going to the work piece but whe the balance is low @ 2 the heat is going into the tungston how does that clean? and what is it "cleaning"? the oxidation already present on the piece, or from post oxidation occuring after welding?

    I really like the 2% thoriated tungston compared to pure... it seems to last alot longer and gives me a pretty stable arc when i grind it right. i would like to try the lathinated or ceriated but my welding supply doesnt stock those.

    I figured out what the issues was...
    The pipe must have some sort of surface coating. I took the angle grinder to it and then hit it with the brush afterwards. The results were way better.

  5. #5
    Join Date
    Jun 2012

    Default Am i experiencing a contamination issue? or Something else

    Remember also that aluminum oxidizes fast, when welding aluminum clean, clean, and clean. I always clean the area of the joint with acetone, then scotch brite followed by clean water.

  6. #6
    Join Date
    Dec 2012


    you should use ceriated (gray identifying band) or pure tungsten (green band) - you can find it online I'm sure.

    Also aluminum requires preheating to release moisture from the material and to encourage it to take weld. and also - CLEAN CLEAN CLEAN, then clean again, then weld

  7. #7
    Join Date
    Jul 2009


    As a practise getting ali from a scrap dealer is cool and cheap but you never know what you are getting. Lets say it was a 2000 series instead of a 6000. You would be experiencing even more issues.
    Ali welding is a constant learning process. Cleaning is part of it, pre heating is another. Some pre heat with gas, others with hot air torches and some just use the TIG torch.
    If your filler rod is left out it will have an oxidation layer. If there is any cutting saw coolant left on your work piece it will soot up the puddle. Sticker residual & oil are problems if not cleaned away. Anodise major issue.

    Welcome to ali welding
    Its a lot of fun

    Grip it and Rip it

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