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  • Machining a torroid

    I have been trying to figure the best way to machine a torroid shaped object. Say 5/8" ID with a cross section of 3/8", 1-3/8" OD.

    What would be the best way to machine something like this. Lathe? Machine one half of the inside radius, flip over, and machine the other half. Then hold it on an arbor to do the outside?

    Or mill it out?

  • #2
    What kind of accuracy does this thing need to have?

    Some clever maneuvering with the right kind of ball turner would do the job (obviously interference is an issue).

    If available, I'd attempt some sort of tracer-based shenanigan.

    Either way, it'll be a lot of planning and forethought. Anyone you know have a CNC lathe who would be willing to pop this out for you in short order?

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    • #3
      Originally posted by macona
      I have been trying to figure the best way to machine a torroid shaped object. Say 5/8" ID with a cross section of 3/8", 1-3/8" OD.

      What would be the best way to machine something like this. Lathe? Machine one half of the inside radius, flip over, and machine the other half. Then hold it on an arbor to do the outside?

      Or mill it out?
      Once the basic ring is shaped, seems a natural for clever clamping on a rotab and cutting with a 3/16" round over bit.

      Lloyd

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      • #4
        My mill is CNC and I had though about using a corner rounding bit.

        Tolerances arnt high.

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        • #5
          Or if precision isn't required, a 3-jaw and a file.
          Just got my head together
          now my body's falling apart

          Comment


          • #6
            i'd do it with form tools, that one way model hand wheels are made. The ID is made with a half circle ground into a cutter and the outer cutter forms the OD then parts off. For making hand wheels, the hub is also made and the spokes are drill for and then soldered in prior to OD machining. Granted, the shape you describe at 3/8 is a going to be a heavy cut, different proportions than a model hand wheel....maybe make 4 cutters, each cutting 1/4 of the toroid?

            I confess I've not done this, but have had it explained and seen the results.....been thinking about it as I've the reversing hand wheel to make on the Stuart triple and the above approach would better than a disk with holes drilled in.
            .

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            • #7
              I'm intrigued Macona Knowing that you're heavily involved in your AC servo retro-fit, what's the toroid for?
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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              • #8
                If this is a handwheel rim, or similar, what about back to basic black smithing?
                IE, roll it out of rod/bar and weld.
                Just got my head together
                now my body's falling apart

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                • #9
                  Originally posted by Swarf&Sparks
                  If this is a handwheel rim, or similar, what about back to basic black smithing?
                  IE, roll it out of rod/bar and weld.

                  Just what I was thinking! It'd be alot faster to form it from round bar than machining it from solid. Less waste too - but maybe you can't do that for your application. A 5/8" bar in the vice (or hardy hole) and a torch (or forge) and wrap it around, weld, done. If you need, you can take a bit of larger bar and turn it down to 5/8 so you have a shelf to insure that the ring is flat.

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                  • #10
                    Or to be crude, rude and original.
                    Just cold bend it round a suitable former in the bench vice, cut with angle-grinder or hacksaw (preferably at an angle to the axis) then weld.
                    Sorta like chain mail links or jewellers' chain.
                    Just got my head together
                    now my body's falling apart

                    Comment


                    • #11
                      Actually there really is no particular application involved, though I could have used something like it in the past for some HV terminals.

                      Comment


                      • #12
                        Ah, OK Macona, my hopes are dashed

                        By the way, without hijacking your own thread, what was the sprocket and potentiometer thingy for on the servo retrofit? I'm guessing it was some kind of speed control for the servo controller, but why would you need the bicycle sprocket?
                        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                        • #13
                          HV terminals, perhaps HF?
                          The name Tesla has been bandied about here quite recently
                          Just got my head together
                          now my body's falling apart

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                          • #14
                            Lazlo, Did you see the vids of the lathe working?

                            The sprocket thingy is the mount for the original rheostats. The EE with the motor generator used a very special tandem rheostat to control field voltage and armature voltage. Each rheostat was about 8" in diameter. That bracket is a spare bracket and sprocket I had so I modified a regular pot to use the same bracket. No since re-inventing the wheel.

                            If you didnt catch the tiny video of the lathe cutting check this out. .125" DOC, 17-4 stainless, .0065" feed.

                            http://www.youtube.com/v/tmU9nnXDeKg

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                            • #15
                              Originally posted by macona
                              Lazlo, Did you see the vids of the lathe working?
                              Yes I did -- the improvement was spectacular!

                              The sprocket thingy is the mount for the original rheostats. The EE with the motor generator used a very special tandem rheostat to control field voltage and armature voltage. Each rheostat was about 8" in diameter.
                              But don't you disable all that when you're controlling the servo directly from the Mitsubishi servo controller? Are you using that potentiometer/sprocket so the analog RPM sensor in the headstock shows the correct speed?
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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