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  • Cutting a Spring

    When you look at a "bought" spring, the ends are nicely finished square. So if you have a length that you want to cut, how do you finish it off like that? I typically cut it with wire cutters, then trim them up on the grinder, deburring.

    I have read a spring cut like I did, doesn't " load" evenly, and release evenly.

    Thoughts?

  • #2
    Technically you need to finish the ends prior to heat treat and grind to finish after heat treat.
    There are bodges, though these should not be discussed where purists will jump all over them as poor practice ;-)
    If you benefit from the Dunning-Kruger Effect you may not even know it ;-)

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    • #3
      Originally posted by Magicniner View Post
      Technically you need to finish the ends prior to heat treat and grind to finish after heat treat.
      There are bodges, though these should not be discussed where purists will jump all over them as poor practice ;-)
      At the risk of excoriation by said purists, I'll describe how I cut motorcycle fork springs.

      - Cut 1-1/4 coils less off the end than the desired end result;
      - heat the last full coil to red heat with propane torch;
      - mash the heated coil down completely with a block of steel (usually a 1-2-3 block);
      - grind the end flat with bench grinder, finishing with the side of the wheel.

      Obviously the last coil is no longer heat treated, but then it's also no longer part of the active spring since it's collapsed against the second coil. Who cares if a non-flexing part of the spring isn't springy?

      -js
      Last edited by Jim Stewart; 11-02-2017, 06:16 PM.
      There are no stupid questions. But there are lots of stupid answers. This is the internet.

      Location: SF Bay Area

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      • #4
        He's a Witch!
        Burn Him!

        I do that with compression springs too, never had a failure
        If you benefit from the Dunning-Kruger Effect you may not even know it ;-)

        Comment


        • #5
          Originally posted by Jim Stewart View Post
          At the risk of excoriation by said purists, I'll describe how I cut motorcycle fork springs.

          - Cut 1-1/4 coils less off the end than the desired end result;
          - heat the last full coil to red heat with propane torch;
          - mash the heated coil down completely with a block of steel (usually a 1-2-3 block);
          - grind the end flat with bench grinder, finishing with the side of the wheel.

          Obviously the last coil is no longer heat treated, but then it's also no longer part of the active spring since it's collapsed against the second coil. Who cares if a non-flexing part of the spring isn't springy?

          -js
          That's what i do as well. It's still a better spring end than just cutting without flattening.

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          • #6
            Another vote for the heating and flattening
            CNC machines only go through the motions

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            • #7
              Thanks, you guys, that's a real good technique to remember!

              metalmagpie

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              • #8
                I've done it by cutting the spring long, then grinding the last 3/4 of a coil flat using lots of pressure. The end gets hot enough to soften it and is easily pressed flat. It was with springs from wire at less then 1/8" diameter.
                North Central Arkansas

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                • #9
                  Music wire springs were coiled cold. You should be able to use pliers to close the last turn without heating. If you have a small spring I suspect it is music wire. Most of these small springs do not have ground ends.

                  If you have a larger spring, do what the other guys said.

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                  • #10
                    Makes sense, thanks guys.

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                    • #11
                      Dip it in Evapo rust
                      "...do you not think you have enough machines?"

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                      • #12
                        I just hold the end to a belt sander. It sands the end flat, while also heating it. The light pressure of the process makes it a closed and ground end.
                        Kansas City area

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                        • #13
                          On small springs I use a couple of pairs of pliers to ease the last 3/4 turn down so it's more or less flat. You just have to reach in and grab the last half turn one way and the 3/4 turn point and give it a bit of a twist. Takes a couple of tries to get the hang of it and find the "sweet spots" for the pliers that give the best result.
                          Chilliwack BC, Canada

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                          • #14
                            For smallish springs, I stick a piece of 1/4" steel bar in the vise and heat it to dull red. Then I press the cut end of the spring against the hot steel and it collapses the last coil to flat. Then for a ground end a quick pass on the belt grinder suffices.

                            RWO

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                            • #15
                              I have used BCRider's technique in the past and it seems to work OK. But I will have to try this next time I am shortening a spring.



                              Originally posted by RWO View Post
                              For smallish springs, I stick a piece of 1/4" steel bar in the vise and heat it to dull red. Then I press the cut end of the spring against the hot steel and it collapses the last coil to flat. Then for a ground end a quick pass on the belt grinder suffices.

                              RWO
                              Paul A.
                              SE Texas

                              And if you look REAL close at an analog signal,
                              You will find that it has discrete steps.

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