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  • Tube Bending minimum radius help needed

    I would like to bend some 1.375" x .080" Chromalloy tubing to 5 or 6" radius.

    I will be making my own bending dies for this and will be using a Greenlee 555 Bender with a pinch roller like the one pictured below





    Is it do-able ? - or is there some rule of thumb minimum radius I would be exceeding. Sorry its virgin territory for me and thought I would ask before I start cutting the die

  • #2
    I am always amazed at how well and how little a radius automotive exhaust pipe/tube can be bent/formed.

    Why not try a local shop for info and methods/processes?

    Or a BBS for that sort of interest/work?

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    • #3
      Originally posted by oldtiffie View Post
      I am always amazed at how well and how little a radius automotive exhaust pipe/tube can be bent/formed.

      I don't believe a muffler shop worries about slight wrinkles or deformation of the tubing they use for your muffler.

      But yes I've seen the discussions before claim they use a "Mandrel Bender"

      Comment


      • #4
        How many tubes do you plan to bend? I have bent 1" tube with heat, sand filled to a 3" radius with no problem, first time, without a mandrel, just a template to check my curve, O/A torch for heat and bending the tube by hand.
        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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        • #5
          Look at jd2 https://www.jd2.com/p-32-model-3-bender.aspx

          Thay make an 1.375 x 5.5"R and a 6.5"R

          .095 is stated minimum wall.

          There are plans online to make the entire unit if you wanted.

          Protools is also another option .

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          • #6
            The manual for my Parker mandrel benders says if the wall divided by the tube OD is less than .07 you have unacceptable tube deformation without an internal mandrel.

            I would have to check what radius dies Parker offers in that tube size to see if your radius is within their limits.

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            • #7
              Originally posted by DR View Post
              The manual for my Parker mandrel benders says if the wall divided by the tube OD is less than .07 you have unacceptable tube deformation without an internal mandrel.
              Thanks - I think that is the information I'm looking for. At .083 wall I should be good

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              • #8
                Originally posted by Black_Moons View Post
                How many tubes do you plan to bend?
                More then 1 or 2


                Comment


                • #9
                  Originally posted by JoeFin View Post
                  Thanks - I think that is the information I'm looking for. At .083 wall I should be good
                  .083/1.375 = .06

                  That's not in the acceptable range for bending without an internal mandrel.

                  Comment


                  • #10
                    Nice looking chassis. What are you building?
                    I have a Pro-Tools 105 bender and always use their available die centerline radii when designing tube frames or roll cages. I also have a Harbor Frieght tubing roller to make large radii bends. I am designing a tube frame for a Model A right now and it will require some large radii bends to fit the body contours.



                    Lets see some of your project!
                    Mark

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                    • #11
                      Pro-Tools list of bending dies for a 1 3/8" O.D includes:
                      4 1/2" CLR minimum wall is .095
                      5" CLR minimum wall is .083
                      6" CLR minimum wall is .058
                      Using a 5" radius your .083 will be fine.
                      http://pro-tools.com/diesets.aspx
                      Last edited by astroracer; 03-07-2015, 11:53 AM.

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                      • #12
                        Originally posted by JoeFin View Post
                        More then 1 or 2


                        So, 4 by the look of it? Still doable with heat no problem. likely take you about as long to heat bend them as make the die.
                        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

                        Comment


                        • #13
                          JoeFin, you're going to have to help me out here and explain what is Chromalloy tubing. I have no idea what it is and have never worked with it.

                          Did you mean Chromoly? If in fact you are using chromoly, I have a little experiance using this in flat track race bike frames and it looks like overkill for what you are trying to build.

                          Is this frame that you are building for racing, where you need a material that is tough and light?
                          If not you may be better off using mild steel tubing and not 4130 chromoly.

                          I will wait for your reply on the material you are using before I say much more, but I know from experience if it is chromoly,you will not like the results from heating and bending and also with this material you only get one chance at the bend because once it is bent your not going to do much else with it.

                          Dave

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                          • #14
                            Originally posted by d kirby View Post
                            JoeFin, you're going to have to help me out here and explain what is Chromalloy tubing. I have no idea what it is and have never worked with it.

                            Did you mean Chromoly? If in fact you are using chromoly, I have a little experiance using this in flat track race bike frames and it looks like overkill for what you are trying to build.

                            Is this frame that you are building for racing, where you need a material that is tough and light?
                            If not you may be better off using mild steel tubing and not 4130 chromoly.

                            I will wait for your reply on the material you are using before I say much more, but I know from experience if it is chromoly,you will not like the results from heating and bending and also with this material you only get one chance at the bend because once it is bent your not going to do much else with it.

                            Dave

                            Yes Dave

                            It is Chromoly - you can blame "Spell Check" for Chromalloy

                            No at 112 lbs I don't think it is too heavy given the class was a minimum weight of 1000 lbs. The main consideration was to limit contortion to 1 deg per 5000 lbs of force. And No, that model has been scraped already when it was checked for aero

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                            • #15
                              Thanks JoeFin that explains a lot lol !!!
                              Does that mean you are going in a completely different direction now, or are you still thinking of using chromoly?

                              Dave

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