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Thick Material Issue - starts tack but turns into hot wire that does not start bead

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  • Thick Material Issue - starts tack but turns into hot wire that does not start bead


    I have an Eastwood MIG 250 and it has been great so far. I was trying to do a repair for a friend's piece of lifting equipment that had a piece of round tubing maybe 1/8" wall, welded to a 5/8" ish thick piece of steel. The manufacturer must have had their machine set for welding the 1/8" thick piece because that weld popped off like it was done with a hot glue gun.
    Now the single pass capacity of the MIG 250 is 1/2". I figured I would give it a try laying a root or first pass and I had the machine on the suggested 1/2" thick setting. If it went well maybe I could do some extra passes.
    When I went to lay a bead, it started the initial tack/puddle and it made a bead, then just started pumping wire but the wire wouldn't melt, it would only be red hot. I have it plugged in for 240/250V with a dedicated 50 amp breaker and it didn't pop the breaker, no overload light on the welder.
    I had a divot in my table I believe from the electricity searching for a connection as I was clamped to the table and not the part and hadn't cleaned the paint anywhere on the part except for where I was welding so it arched to the drilled holes.
    I then clamped onto the tubing and still had that issue (maybe the clear coat on it was affecting the connection?). I cannot remember if I clamped onto the cleaned surface of the 5/8" plate, but I believe I did.
    Either way I could only basically do extended 1-1.5 second tacks without the puddle dying and red hot wire getting pumped onto there looking like a sea urchin. I ended up doing those tacks all the way around. I know they are not as good as a solid bead all the way around, but I think it will hold better than what the manufacturer did.
    Any idea what this issue was?
    Should I have just ground a clean spot on the part for the ground clamp and not trusted the round tubing?
    Should I have reduced the wire speed?

    Threw in a picture of a workout bench I was making for someone that was welding just fine before I tried to do the thick piece.

    Also, side note that I have wondered about as I took welding classes a few years ago doing mig and tig, and we would do multi-pass welding, but I was always curious, how do you determine WHEN to do a multi pass weld, and if your machine can do it. Like they say the machine is capable of doing 1/2" in one pass, which I interpret as you can get the penetration needed. So what, if it is more than half inch, you should do a bevel to at least 1/2" thickness, and then you can stack? Does that mean you could weld 1" plate with a welder that only has the capacity for 1/4" if you bevel the plate down to 1/4" and stack?

    Sorry long winded, but I have been wondering this for a while as I am doing various welding projects.

  • #2
    No matter what you need a good ground, since that is in question grind a clean space for it, on the weldment and then try again, either the issue will be resolved or you'll have ruled out the ground as the problem
    West coast of Florida


    • #3
      With it working for 1-1.5 seconds then stopping, I would assume there's something wrong with the welder. Bad grounds and such wouldn't be nearly so predictable. Something overheats and goes high resistance, a problem with the power input circuitry causes it to work only until the filter caps drain, etc. Contact the manufacturer and explain the symptoms to them, see what they say.


      • #4
        I should add, double-check your input power. Put a meter on the input to the machine and watch the voltage while trying to weld (just aim at a piece of scrap off to the side where you won't get arc blinded). A high resistance connection in your input power could also do that, and the machine might not complain since it's designed to work on 120 as well.


        • #5
          Grounding problem.


          • #6
            Yes you should always make sure you have a clean bare metal ground.
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