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Millermatic 35 porous bubbly welds

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  • Millermatic 35 porous bubbly welds

    Hi, guys & gals!

    Just a heads up to maybe save folks some trouble one day. Had some serious trouble with my wonderful old Millermatic 35, very porous welds. Beads looked all bubbly like lava. Way beyond pinholes, more like bubbles and craters. Tried every adjustment, no good, always the same.

    Took the Tweeco gun lead loose and found one o-ring missing and the other one split through where the lead hose connects down at wire drive motor. Replaced, tried her again, same problem!

    Checked, cleaned and reconnected ground clamp wire and cleaned clamp jaws, checked all the Tweeco gun hardware, fittings and parts, replaced tip and stuff, cleaned all the plug-in taps. Had already replaced main contactor for another problem before this. Tried various methods of shielding the work area, cleaning the metals super clean by grinding, brushing and even emery cloth followed by solvents and acetone: same thing no matter what, little Mr. Bubbles for welds!

    Machine had been stored outdoors under heavy tarps in a very dry, high desert environment. Well I finally picked up another spool of JW Harris ER70 wire and stuck it in: PRESTO-CHANGEO! Instantly back to gorgeous smooth beads, a joy to behold, YEEEE-HAAAAAW!

    The 2 year old spool of JW Harris ER70 looked perfectly good, no corrosion or apparent contamination of any kind even on close inspection. Regardless of what it looked like, that was the problem: contaminated wire! Considering the very dry desert environment here and still getting contamination or corrosion, it seems best to remove your spool of wire and store inside if machine is stored outdoors under tarps or in a somewhat open area for any real length of time. Saves a lot of hassles and a chunk of change too!

  • #2
    I would do a test and put the Harris wire back on and see if it still bubbles. Just wondering...Bob


    • #3
      Originally posted by aametalmaster View Post
      I would do a test and put the Harris wire back on and see if it still bubbles. Just wondering...Bob
      Thanks for the tip! Under different circumstances I might agree, but not this time. I had the first spool in the machine since I bought it, about 6 years ago. Used it originally for a large project where it welded just gorgeous beads, even amazing. Then moved and the machine had to be stored under a tarp. It still welded beautiful beads when I first got here right after project completion, then it sat unused for about 3 years.

      Next time I fired it up it was all messed up. That's when I replaced the main contactor. New contactor didn't help the bubbly porous welds but got it welding consistently when I pulled the trigger. Posted numerous times on 3 forums describing the problem and tried many cures. During that time I discovered 1 bad o-ring and another one missing at gun lead connection at drive motor. Also R&R'd several other items while I was at it. Regardless of what I did the welds were entirely consistent: LOUSY and very porous and bubbly, like real bad every single bead or tack, no exceptions out of dozens upon dozens.

      Finally able to swap out the wire spool and instantly have my old machine back, downright beautiful welds, perfectly smooth, not a trace of porosity. Based on that it seems obvious to me that I finally discovered the problem. Thanks!


      • #4
        I think in all of the fiddling you might have bumped something back in place and the wire was just a concidence. Just my thoughts...Bob


        • #5
          Your description of the welds is usually the result of running out of gas. If the wire wasn't spotted with rust then there's likely nothing wrong with it.


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