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Rollbar bend radius

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  • Rollbar bend radius

    I read in some welding handbooks that the minimum bend radius is 3.5 x Pipe Diameter. That means for rollbar piping, it should be 3.5 x 1.75 = 6.125" Radius.

    JD2 sells 5.5" radius and 6.5" radius for this diameter piping. Will using the 5.5" radius die make the pipe too weak at the bend area? I have been told it is fine, but I do not want to compromise strenth at all.

    Please help!


  • #2
    First, I have to differentiate between piping and tubing. Tubing is measured by outside diameter and wall thickness. Piping is measured by inside diameter (and wall thickness, I think). A pipe bender WILL kink your tubing. Make sure to differentiate when making a purchase. I bought a pipe bender and tried to bent tubing, it didn't work.

    Next, I have also seen the rule of 3.5 times the tube diameter, however, I have a bender ( that does 1 3/4" tubing with a 6" radius. I havn't used it yet for this tubing, but other tubing sizes work great. I don't think that the manufacturer would sell this size die to the general public if it would be a hazard.

    Personally, I think that your radius is not impossible nor unsafe. Hope this helped.

    Hobart 135
    Oxy-Acet w/ Victor torch
    Dynasty 200 DX


    • #3
      Usually, the manufacturer will supply a chart showing the diameter of the die, and the minimum wall thickness of tubing it will bend ............It is the thickness of the wall that determines the minimum radius.......

      For example, Hossfeld lists an 1 3/4 die on a 6in. radius, with a minimum wall thickness of .083............ It will bend 083, 095, 120, will wrinkle can go thicker, just not thinner than the minimum wall...........

      The same style of die in 1 1/2 diameter will bend 083 on a 5in radius.......

      Now, different manufacturers use differing methods to describe thier dies.........For example, Hossfeld uses centerline radius........some will use inside radius and some out side.........So a chart for Hossfeld doesn't work for them..........

      Bottom line, check with the manufacturer.........they will have the minimum wall for all thier dies


      • #4
        I have the JD2 model 3 bender. As far as being technical differentiating between piping and tubing, I make the mistake often. I plan on using DOM 1.75x.095 tubing.

        SCCA recommends 3 x Tubing OD = Minimum bend radius. I think I am fine with what I ordered.

        Thank you for your help!