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  • welding a cage

    Hi all,

    I'm intending to build a project car next season. I don't intend to have a shop do any of the work for me. I have the tools and means to do everything at my father's shop.

    I know that the rules and regs give the specs for rollcages, but could I get some hints and tips from people that have done it before?

    One of my questions is, does it matter what type of welding I use? Dad's shop has Mig and Arc. I was reading some discussion on welding at this forum and from what I gather, arc is easiest to learn and is perfectly acceptable for the thickness of steel used in a cage.

    And for those of you thinking "this joker thinks he can just learn to weld by making a cage for a racecar? He's dead"... dad is the one with the expertise in welding and he'll be making sure its all good so I don't die.
    Last edited by MazdaMatt; 07-18-2006, 10:48 AM.

  • #2
    Re: welding a cage

    I'm sure your Dad is an excellent welder, but unless he's done one before constructing a cage is truly an art form. I would have it done by someone whose done it before (Four Star Motorsports, O'Brien Motorsports) There is story in the new issue of Inside Track on Dan Sprongl's off in the U.S. and how the cage saved his life.
    CASC Autoslalom Director
    2019 Honda Civic Si #64
    www.twinlakesmc.org

    Comment


    • #3
      Re: welding a cage

      I understand the emphasis on safety when it comes to roll cages, but.... There was a time when the welders at Four Star Motorsports or O'Brien Motorsports built their first cage. If they had decided to let the experts of the day do it instead, then who would be welding cages for us today?
      CarGuy - Subaru BRZ #57
      sigpic
      Racing is life. Anything before or after is just waiting. Steve McQueen

      Comment


      • #4
        Re: welding a cage

        MIG is the easiest, make clean joints, use gussets, and use proper backing plates. Try to get the backing plates welded to more than one plane. Use the correct material for the weight of the car and follow the CASC specs. Follow the basic 6 point design, and add triangulation where needed. Make sure you uses a proper tube bender and notcher..

        its not rocket science so I am sure if your dad is a metal worker you both can make a nice cage for less than 1/2 the cost...

        a basic 6 point cage per CASC specs material wise is about $300 or so....so when you see costs of $2k+ I dont blame you for making your own..

        look around for tube suppliers thier prices vary ALOT.. from $4.00/ft.. to $10/ft for 1.5" dom .125 tubing...

        when in doubt....make it stronger with gussets and some more triangulation points..

        it should take you maybe 9-11 hrs of work to do a full 6 point depending on how fast you can bend and notch well..
        Former CCC member, and shit disturber

        winner of a bunch of different classes over many years

        breaker of parts, burner of engines

        CREATOR OF "ULTIMATE DOOM 570SX"

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        • #5
          Re: welding a cage

          Valid point, valid counterpoint. I'm going to stick with counterpoint on this one. I'm not making some insane 400whp monster, here. Just a simple solo1 project with a cage, gutted, exhaust, intake, wheels, brakes.

          I plan on looking at all of the regulators that I may in the future be governed by and build a cage to the most restricting guidlines. And just like Erik in the bimmer at the SoloSchool, my cage will be built not just to get into the race series, it will be built to push the car back over shiny side up and come back next weekend with some fresh paint.

          I'm an information fanatic. I'll let my father do the hard bits, but not till i'm satisfied that we know everything about how to design/engineer a safe cage. I'm not afraid of a little trigonometry.

          Thanks for the concern, thanks for the confidence

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          • #6
            Re: welding a cage

            Originally posted by Carguy
            I understand the emphasis on safety when it comes to roll cages, but.... There was a time when the welders at Four Star Motorsports or O'Brien Motorsports built their first cage. If they had decided to let the experts of the day do it instead, then who would be welding cages for us today?
            I assume they learnt from someone with expirience. Like an apprentice would.
            CASC Autoslalom Director
            2019 Honda Civic Si #64
            www.twinlakesmc.org

            Comment


            • #7
              Re: welding a cage

              6-point refers to the mounting points on the floor, correct? the two in front of the driver, two behind the driver and two in the trunk area?

              I see a lot of cages that collect to a central location in the back seat. Is that called a 5-point cage? Legal? Less effective?

              Steve, no worries on the welding and ability to build things. Dad's been working with steel on transport trucks for many years, he knows how to build tough. I see a lot of his good work. Once we've gone over a design and a mockup, I am confident that he'll be able to properly and safely assemble the cage and all supporting bracketry.

              Do any of you know of a book or website that has good information on designing a cage and how to properly attach and suport the bars to the car? Something intended for a welder would be good, not a beginner.

              the CASC regulations say that it should be ARC welded wherever possible.

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              • #8
                Re: welding a cage

                Originally posted by MazdaMatt
                Steve, no worries on the welding and ability to build things. Dad's been working with steel on transport trucks for many years, he knows how to build tough. I see a lot of his good work. Once we've gone over a design and a mockup, I am confident that he'll be able to properly and safely assemble the cage and all supporting bracketry.
                That's cool. Maybe he'll end up with a side business.
                CASC Autoslalom Director
                2019 Honda Civic Si #64
                www.twinlakesmc.org

                Comment


                • #9
                  Re: welding a cage

                  Originally posted by MazdaMatt
                  6-point refers to the mounting points on the floor, correct? the two in front of the driver, two behind the driver and two in the trunk area?

                  I see a lot of cages that collect to a central location in the back seat. Is that called a 5-point cage? Legal? Less effective?

                  Steve, no worries on the welding and ability to build things. Dad's been working with steel on transport trucks for many years, he knows how to build tough. I see a lot of his good work. Once we've gone over a design and a mockup, I am confident that he'll be able to properly and safely assemble the cage and all supporting bracketry.

                  Do any of you know of a book or website that has good information on designing a cage and how to properly attach and suport the bars to the car? Something intended for a welder would be good, not a beginner.

                  the CASC regulations say that it should be ARC welded wherever possible.
                  I guess ARC welding refers to MIG ... noone in their right mind would use a stick welder. TIG welding is very nice though, and you end up with nicer welds, if done correctly. When I had my cage done, it was only the second cage done by Jeff, and I think it came out fantastic. He now has his hands full with many projects.

                  That said, I also spent a LOT of time researching and designing the cage. Granted, mine is a bit more than your basic 6 point, but proper load paths and triangulation are key to a safe cage. Learn about that, and look at well built cages for your car to see what others have done. The key point is wherever you have a joint, to make sure it does not end in the middle of a tube ... always join to a point, and never make a T if you can avoid it. Your notching and bending will determin how nice the cage comes out ... the welding is the easy part
                  Arek Wojciechowski
                  8legs Racing, SPC #77
                  http://www.8legsRacing.com

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                  • #10
                    Re: welding a cage

                    Originally posted by sjd
                    I assume they learnt from someone with expirience. Like an apprentice would.
                    Like MazdaMatt's dad.
                    CarGuy - Subaru BRZ #57
                    sigpic
                    Racing is life. Anything before or after is just waiting. Steve McQueen

                    Comment


                    • #11
                      Re: welding a cage

                      Assuming your father's a competent welder you're half way to being able to build a decent cage. He'll be able to tell you when the metal is clean enough and the joints fit tight enough, know that he can't weld to a sealed tube and how much clearance he needs to weld a joint. Welding a cage is much more challenging than welding on a bench due to the limited space inside the car. Be certain to fully weld all the joints even if that last 1/2" of weld requires your best imitation of a contortionist to reach and see at the same time.

                      As for the design, think triangles and follow the guidelines in the CASC race regs. A cage is basically a 3D truss. Triangular elements make strong and stiff structures because the individual members are only loaded in tension or compression. Obviously there are cases where it is difficult to have triangular elements such as the side window and windshield openings but its easy to put a diagonal brace across the roof, in the doors, etc. Try to tie the mounting plates into vertical surfaces. Think the cage design and build process through before starting. Consider how you'll give the driver the most space possible while still being able to get at the joints to weld them.

                      I think Adam's estimates are on the light side. $300 might get you enough material for the most basic cage but budget much more than 9-11 hours of labour. Assuming the car is already stripped, you're MIG welding and you build the most basic cage to meet the race regs, I would suggest 15 to 20 hours. One you start adding another brace here, a diagonal there and mounting plates that tie into the vertical sheet metal, etc, that number can easily double or triple.
                      Jeff Graves

                      Ongoing Miata project

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                      • #12
                        Re: welding a cage

                        Thanks for the good advice. I think i'll try to 'acquire' or make use of a school version of a 3d modeling program. Often they have modules for things like tube-steel manufacturing.

                        For a START, i will be looking at the diagrams for 6-point cages found in the CASC regs (appendix 'o'?). From there, its all about triangles.

                        You say that I should be using points, which makes perfect sense... Should I be mating braces (for example the ones that cross from the front loop to the main loop along the sides of the roof) right on the bend? or "as close as possible" (as the regs suggest)?

                        It is suggested that all connections to sheet metal be made on verticle sheet. The diagrams in the CASC book show all six mounting plates on the floor... Is this incorrect? Would it be better to 'widen' the angle of the legs so that I must cut the tube at an angle for an eliptical intersection to plates on the walls? Wouldn't more strength be found on the floor near the rails?

                        Anyone have detailed pictures of their cages? I'm sure we'd all like to see and scrutinize designs.

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                        • #13
                          Re: welding a cage

                          yeah if you are building a 1 off cage then $300 is a bit low, I buy the DOM tubing in 500ft sections so I get a better price..


                          9-11 hrs with 2 people should be more than enough time if they are both working.. 1 welding 1 cutting and bending..for the basic 6 point..

                          now if you start to go tube crazy like Arek's cage thats a different story
                          Former CCC member, and shit disturber

                          winner of a bunch of different classes over many years

                          breaker of parts, burner of engines

                          CREATOR OF "ULTIMATE DOOM 570SX"

                          Comment


                          • #14
                            Re: welding a cage

                            I want to check out Arek's cage; anyone got pics? I recall you guys poking fun at it in the RV at the soloschool, and his response was that he prefers to just push the car back over and drive away rather than buy a new car. Seems like a sound plan to me, but of course I would just start with the basics.

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                            • #15
                              Re: welding a cage

                              Matt, do you have a particular car in mind? Maybe you can see if anyone locally has the car you have in mind with a cage already in it to get ideas.
                              -=Brian=-

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