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How to weld a mild steel roll cage

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  • How to weld a mild steel roll cage

    Hello,

    I want to learn to properly weld a roll cage into a production based racecar. The cage would be contructed of 1.5" OD x .095" wall DOM Steel Tubing.

    I will be using my Millermatic 212 with .030" wire and 75/25 argon/co2 mix.

    Any tips or suggestion on starting settings for my Millermatic and techniques for welding the cage is much appreciated.

    Thanks

    Greg

  • #2
    Try to get good fit ups in all your connections. Move around while welding so as not to get to much heat in one area. If your not sure of your welding skills then get someone who knows.

    Comment


    • #3
      Greg,

      As MMW said, fit up will be critical for a good cage. I'd also suggest in investing in a good tubing notcher, such as a JD2, Ol' Joint Jigger, or a JMR tubing notcher. Having well cut tubes will make a big difference on how the quality of your weld turns out. I'd also cut up a bunch of test joints to practice on.Tack the new tube in at least 3 places to prevent movement, and then proceed. Start with going around the tube joint a 1/3 at a time, till you become proficient enough to do 1/2, or all of the joint at one time. Again, paying attention to heat, and quality of weld.

      Another tool that will help along the way is called a "Pipemaster", basically, it patterns what the cut on the tube your joining to the rest, should look like, and gives you a pattern to cut to for a good joint.



      Hank

      Comment


      • #4
        Originally posted by Greg K View Post
        Hello,

        I want to learn to properly weld a roll cage into a production based racecar. The cage would be contructed of 1.5" OD x .095" wall DOM Steel Tubing.

        I will be using my Millermatic 212 with .030" wire and 75/25 argon/co2 mix.

        Any tips or suggestion on starting settings for my Millermatic and techniques for welding the cage is much appreciated.

        Thanks

        Greg
        What kind of racecar are you planning to build? Just wondering about the 1.5" x .095" DOM size.

        My tip would be tack the entire cage together before any finish welding to keep warping to a minimum. Jump around as opposed to welding in one area to keep heat down as stated above.

        Comment


        • #5
          A big + 1 on all above. Have to recomend a DVD for ya. RON COVELL "Working with tubing." I have a few of his DVDs and there a good deal for the price. Lots of info. You can order them here. http://covell.biz/ One day Ill have the complete set.
          Last edited by Blue Collar Moto; 04-02-2008, 01:33 AM.

          Comment


          • #6
            And heres a good article on tubing notchers. For a real good one you have to modify it.
            http://www.bikerradiomagazine.com/fo...pic.php?t=4059
            Last edited by Blue Collar Moto; 05-07-2008, 11:22 AM.

            Comment


            • #7
              Thanks to everyone, We are building a roadrace car to SCCA specs. I have quite a bit of time to practice seeing that we will not be doing this till next fall/winter (the cage will come in kit form requring fitting and welding).

              What about heat settings and wire feed speed? I read the article here on the Miller site about Hendrick Motorsports using the Millermatic 210, the article mentioned heat settings of 4 and 5 and wire speeds of 35 - 45 IPM if I remember correctly, just not sure of the specs for the NASCAR cage, I believe it is DOM mild steel, as for the wall thickness, I have no idea.

              Also, what about welding the cage to the rocker panels/firewall of the car, any special considerations in doing this work?

              Thanks

              Greg

              Comment


              • #8
                Greg,
                Remeber someones life could depend on this cage.If not done properly and it fails to protect well.
                Have someone chk your work. and practice as suggested to get the feel of doing round tubibg

                Also weld settings are just " starting points" get you close ,most welders adjust to their liking and speed and weld character.At least thats how I do it .

                Most cages use 3/16's plates to distrbute the downforce of the tube in case of rollover .

                Proper cages usually sit right on top of the main frame rails.

                But I'm not up on SCCA cars and design.

                If its your first cage seek someone to inspect your plan before doing it.

                have fun
                Rich

                Comment


                • #9
                  As Fortyfords said, have someone check your work. When I built my 25.4 chassis, I asked questions of a couple different track tech guys I know. And, probably most important, I asked many questions of the NHRA inspector that would eventually be tagging the chassis. That way if he red flagged something, I could say, "but that's how you told me to do it".
                  BTW It passed first time by NHRA & IHRA, I think mainly because I kept them in the loop during the build process.

                  Comment


                  • #10
                    Get and study the SCCA rule book if you have not done so alleady. Be sure you are building to your class too. It will set the guidelines and rules you have to follow. Things like the square inch size of each cage foot, total number of bends in a main hoop, support tube angles, total number of contact points and many other important details are all spelled out. The actual welding is about 5% of the time spent building a good cage IMO. Thinking, planning, drawing, cutting, bending, fitting, cutting, fitting, recutting, fitting and tweeking are about 90%. The other 5% is grinding paint off and cleaning up beer bottles (in some shops).

                    Look a the other good work and methods. This is not a try it and see if it works kind of thing. Testing and having a cage fail in real world is bad news for the crash test dummy. The cage feet have to resist being pulled away as much as being pushed down. A rollover is far less common than a hit in the sides. A cage needs to be able to resist being deformed from all directions.

                    (edit) Installing a kit cage, the cage will likely come with instructions.
                    Last edited by Vicegrip; 04-02-2008, 08:02 AM.

                    Comment


                    • #11
                      I don't know what your taps equal in voltage but would
                      suggest the the wire speed numbers you posted will be way
                      out of the starting ballpark. I'd be thinking something
                      more into the 200ipm range to start with.

                      Edit
                      You want to make up some practice joints. Don't just do em flat
                      on a table, do them overhead, sideways, stand on one foot using
                      your left hand with one eye closed etc. Do em while your upside
                      down with sharp objects poking you in the ribs and back with
                      sparks falling down your neck and you can't really see the weld area.
                      These are real cage welding practice problems.
                      Dave P.
                      Last edited by FM117; 04-03-2008, 08:03 AM.

                      Comment


                      • #12
                        Originally posted by FM117 View Post
                        You want to make up some practice joints. Don't just do em flat
                        on a table, do them overhead, sideways, stand on one foot using
                        your left hand with one eye closed etc. Do em while your upside
                        down with sharp objects poking you in the ribs and back with
                        sparks falling down your neck and you can't really see the weld area.
                        These are real cage welding practice problems.
                        Dave P.
                        Is there a practical welding test like this?

                        Comment


                        • #13
                          Originally posted by FM117 View Post
                          I don't know what your taps equal in voltage but would
                          suggest the the wire speed numbers you posted will be way
                          out of the starting ballpark. I'd be thinking something
                          more into the 200ipm range to start with.

                          Edit
                          You want to make up some practice joints. Don't just do em flat
                          on a table, do them overhead, sideways, stand on one foot using
                          your left hand with one eye closed etc. Do em while your upside
                          down with sharp objects poking you in the ribs and back with
                          sparks falling down your neck and you can't really see the weld area.
                          These are real cage welding practice problems.
                          Dave P.
                          Add slithering in and out of the caged car about 20 times an hour too. Get in get placed and find that (fill in the blank) is not on/open/set right/pluged in/long enough or near you. Get out, correct issue, get in get set then get back out to welding hat that is sitting on top of the welder. Get back in and get right back out to answer the phone that is on the work bench and not in your pocket.
                          Last edited by Vicegrip; 04-03-2008, 12:38 PM.

                          Comment


                          • #14
                            Vicegrip,
                            You got the idea, add about 95 degrees and plenty of
                            humidity, somebody that wants it yesterday
                            (and was dumb enough to tell you they bent/broke
                            it 6 weeks ago at their last event).
                            Dave P

                            Comment


                            • #15
                              I would suggest building a rotisserie. "Not just for hog roasts anymore"

                              Comment

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