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Determining Weld Penetration

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  • Determining Weld Penetration

    Hi Everyone,

    I am new to the Miller Forums and have been welding for a while. I am no where near a professional, but just a hobbyist that welds when I need to. I usually MIG with my old Millermatic 35 using the 25/75% Argon/CO2 shielding gas and .030" steel core wire for mild steel. I always prep my joints by grinding down to clean, bare metal, then wiping them down with brake clean, and bevel most joints if the material is .190" (3/16") or thicker material. I usually find the drag method works for most positions I weld in, but will use a push style as required.

    I have never had a weld fail to date, but recently been finding myself starting to self doubt my welds. I tend to over build things, so I am a cautious person by nature. I build cars and bikes and recently did some projects that I am now wondering if my welding is proper? I usually will test settings by taking similar material that I have extra, join it together in like joints, and then proceed to use my hammer, vise, and big hammer to try and destroy it to see if the weld will give. Obviously, this type of testing will not be done on my finished motorcycle frames, trailers, cars, etc... So I am wondering if there is a good way besides weld bead appearance to know that I am getting good penetration? I look for HAZ in the base material to try and help determine, but don't know what else can be done. I have included pics of some of my latest project welds.

    Any feedback would be appreciated.


  • #2
    I am not a pro, but I look at the back side. If the back side shows no signs of being heated, I am not getting enough power to the weld, so I would crank up the wire speed/voltage, or increase the amps in stick or TIG. Obviously if the back side shows weld, that is full penetration. Try looking at the back side, you will see what I am talking about.

    I don't think that this is a great way to tell if the weld is good, but it is kind of a sanity check.

    The bead itself should tell you how you are doing. If it is standing up proud, you need more power. If it is very wide, turn down the power.

    We will see what the experts say.

    Syncrowave 200, Millermatic 211, Victor torch, Propane forge....


    • #3
      That is good feedback. I usually do this, but unfortunately on the current motorcycle frame, not really possible to see on the back side due to it being tubing that is sealed up. These older Japenese motorcycle frames are also usually a poor quality steel that are easy to blow holes in. I stich or pulse weld to control heat better especially when welding thicker to thinner steel.



      • #4
        You should do a Google search on brake cleaner and welding. I'm pretty sure that is bad for you. Acetone is a common chemical to make sure the weld area is clean prior to welding.
        MillerMatic 251
        Maxstar 150 STH
        Cutmaster 42
        Victor Journeyman OA

        A rockcrawler, er money pit, in progress...


        • #5
          Originally posted by elvis View Post
          You should do a Google search on brake cleaner and welding. I'm pretty sure that is bad for you. Acetone is a common chemical to make sure the weld area is clean prior to welding.
          Will do. Brake cleaner is specifically designed solvent to evaporate quickly leaving no residue which is why I have used it before, but will look into it. Thanks for the input.

          Edit: I see it is related to chlorinated chemicals like a lot of brake clean used to be back in the day. Mine is the non-chlorinated stuff, but that was a great warning. I guess from now on, will just use acetone. Thanks again.

          Last edited by Fedwik; 11-05-2014, 02:41 PM.


          • #6
            If it's chlorinated brake clean that's not good.

            Oops, just saw your edit, sorry.


            • #7
              i check the welds on box booms with die-pen (die penatrate) it will let you know right away if there is a none tie end in your weld. if it checks out ok and the weld looks good enough for you it should be good to go. the die- pen isn't the cheapest stuff around costly but good. one more thing i hear alot of welders that say they ran their beads hot thats not such a good idead as it will make the weld strong but it also makes the metal your welding to brittle .seen alot of welds rip the metal out of the base metal.
              Last edited by tommy2069; 11-09-2014, 06:49 AM.