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MM252 Recommended Mig settings for 3/16" steel joints?

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  • MM252 Recommended Mig settings for 3/16" steel joints?

    Let me just say I'm VERY rusty when it comes to Mig and I've never trusted the welding process over stick welding for making strong welds on thick material, but that is probably because stick welding is like riding a bicycle to me when I walk away from it for years.

    Anyways, have a new MM252 bought in 2013 and only used maybe 1/4lb of the wire on it in that time. Seemed like it wasn't feeding right when I first started it all up (rollers just slipping) so thought maybe the wire has an invisible to the eye oxidation I can't see causing the lack of roller traction??? Not sure so for ~$30 thought it wasn't worth my time. Bought a new 5lb of Hobart .035" solid wire for the welder yesterday late afternoon and started piecing together a 3/16" steel box. Going to have a go at making my own gun safe.

    Now I'm use to burning in 5P 6010 and running cover passes with 7018. Those are my favorite 2 rods I've been using since I was like 14. But with Mig I under stand you have a pretty weld with no penetration, so I fear these welds may be some of those.

    Not sure why, but the MM252 settings table for 3/16" steel
    18.4V at 265 ipm

    contradict the Miller Mig welding calculator. by saying I'll need a LOT more wire feed speed? Short Circuit Transfer
    Wire Size & Wire Feed Speed:

    .035" (0.9 mm) at 320-340 ipm Shielding Gas & Voltage Range:

    75% Argon/25% CO2: 18-19 Volts

    These welds just seem like they are hanging off the material too much. I don't seem to have this problem when I'm mig welding flat, but this is more horizontal overhead? I just want this too look nice and smoothed out rather than the bead being so high like this?

    I tried doing different combinations up to 19V and adjusting ipm up to 340, but can't seem to find the right settings I'm pleased with.

    Here are a few pics of the welds. Also, using 'new' 3/16" plate from the local steel supplier in town.

    Any thoughts on how I can get better penetration? If my Airco wasn't acting up, I'd be welding this out with 6010 and 7018.

  • #2
    I'm no expert, but it looks to me like you are traveling to slow for the heat setting. Practice some using a lower heat setting and pay attention to your travel speed, like stick, don't leave until the crater is full and the undercut will go away.


    • #3
      Too slow..? I was wondering about that since it seemed like the bead was high, but I worried that if I traveled faster I would not be getting enough penetration and just be putting a pretty bead of thin welding wire over the thicker steel.


      • #4
        My other concern was if I wasn't set hot enough and maybe that was why it was piling up...? I was tempted to up my setting to when 1/4" recommends, but not sure.

        Figured I'd ask here first.

        It sure takes getting use to jumping from stick to Mig since the travel speed seems so much faster on Mig.


        • #5
          It's mostly experimenting with the heat settings, wire speed and travel speed, you'll find the combination easy enough through trial and error. The settings on the door more than likely are for flat welding, so in your situation they're hotter than you need/want.
          Last edited by tackit; 02-06-2017, 11:58 AM.


          • #6
            I was especially wondering about the welder door settings since they are SO far off of the Mig calculator.

            18.4V at 265 ipm

            or 18-19V at 320-340 ipm

            That seems like a lot of variation in the wire feed speed?

            Can someone refresh my memory of what the wire feed adjusts versus the voltage?

            I am just spoiled to the single amps dial on stick I guess.



            • #7
              Originally posted by clint738 View Post
              ...Can someone refresh my memory of what the wire feed adjusts versus the voltage?...
              To put it simply, wire speed is your amperage. The faster you pour in the wire, the higher current the machine will put into the weld, within its capabilities at the selected voltage.

              And while it might be a pain with such a large and heavy weldment, after you get it tacked together, you might want to attempt moving the safe around so that your production welds are in the flat position. Even though you can weld in the other positions, flat is always nicer.


              • #8
                I agree MAC that welding flat will be nicer. I was just welding the horizontals to get some practice with the machine again since I hadn't uncovered it since probably 2015.

                For 3/16" plate material which voltage and wire speed feed would your recommend to get LOTs of penetration?


                • #9
                  It's been so long since I used a machine that gave me the actual numbers, that I couldn't tell you. Experiment both directions and see what differences you get. Surely you have a few scraps so you don't have a bad a weld on the project?
                  Last edited by MAC702; 02-07-2017, 08:44 AM. Reason: spelling


                  • #10
                    It looks to me that you are trying to keep the puddle centered on the joint? In this instance you should be favoring the lower plate slightly as there is less mass on the top pc. so it will burn in easier there on the edge as opposed to the bottom plate. As you weld you can always roll the puddle up to catch the top then back down, basically weaving. Hope you understand what I'm saying.

                    Don't be afraid to change the machine settings until you find your sweet spot. Two people can use the same machine and have different settings. All charts are just a guideline & require tweaking.
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                    • #11
                      A long stick-out will make your weld crown up like that too, especially out of position.


                      • #12
                        Try removing the mill scale and rust from your base metal in your weld zone area. Doing this should help improve arc quality , puddle wet out, and penetration.


                        • #13
                          When I'm flat welding, I turn the voltage up one volt more than whats shown on the door and the machine welds perfectly. I listen to the arc when setting my wire speed, I use the door numbers just to get close, then I turn the wire feed speed knob up or down until I hear a steady smooth sizzling bacon sound, then I have the sweet spot I'm looking for..
                          Last edited by tackit; 02-08-2017, 12:08 PM.


                          • #14
                            Well, I did a little more adjusting and found I think the joint fit up has more to do with the bead height than my machine settings. Here was a bead height profile I was pleased with. However, the flat butt joint welds with no gap, I'm still searching for the ideal welder settings to make the bead not so high.


                            I know there is some undercut showing... something I have always struggled with actually even when stick welding.

                            But I'm guessing having the fit up with the nice gap between rather than touching 90 degree joint allowed for the bead a place to lay within rather than on top.

                            Machine set at 19.4V 265 ipm


                            Last edited by clint738; 02-13-2017, 02:21 PM.


                            • #15
                              Looks too hot to me.
                              I wouldn't call that a high bead profile.
                              You are talking about travel speed being higher than stick makes me raise an eyebrow pretty quick.
                              Miller used to say the door setting was for a "T" joint. That requires more heat than most.
                              Not really sure what it is you are trying to accomplish here, but simply looking at the "V" shape to your bead, and the end crater shape, tells me you are simply flying to the point of barely being able to keep up with it. If it was say 1/2" thick, then maybe I would say in one pass that was a look I would want.
                              When I look at my 350P chart I go down one full metal thickness size on the chart than recommended for my starting point, just because they want it so stinkin' hot.
                              As far as your "gap" goes......I don't believe you really need that because that would be really thin there anyway.
                              I see my advice may be completely 180 degrees from what you may or may not think. I just know how I get the bead appearance I like to see.
                              I would like more pics up close and some of the back side too.
                              On those first welds I would have been more inclined to turn the part completely upside down for that joint. It would have burned in lots nicer without worry of loosing the edge.
                              Just my observations. I hope that helps some. Play with scrap (like Mac said)

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