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  • Cutting a spiral shaped hole with a mill

    Cutting a spiral shaped hole with a mill.
    How?
    For a tesla turbine for pumping water using hard drive disk.

    Thanks.

    Bill

    Last edited by oldhat; 05-23-2012, 05:06 PM.

  • #2
    My ignorance, sorry...What is a teals turbine ?
    Nothing comes up showing one on Google
    Do you have a Bridgeport ?

    Rich

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    • #3
      What is a spiral shaped hole? Do you mean cutting a spiral slot or ... ?

      Comment


      • #4
        If you need to cut something like a scroll I assume that requires a rotary table and some sort of gearing between that and the table X or Y feed.

        It does not have to be mechanical gearing and could be electronic using stepper motors for example.

        If you need to cut a spiral as in a helix, then a lathe is the machine to do that (I would think).

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        • #5
          Originally posted by Rich Carlstedt
          My ignorance, sorry...What is a teals turbine ?
          Nothing comes up showing one on Google
          Do you have a Bridgeport ?

          Rich
          Dyslexia strikes again!

          Try tesla turbine.

          ave

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          • #6
            a spiral shaped groove....or a helical shaped hole....both difficult but at least not impossible....a sprial shaped hole? on that my brain quits
            .

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            • #7
              Sorry typo. tesla

              Spiral shaped hole from a round stock





              Trying posting picture first time

              Bill

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              • #8
                Number 2 pix

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                • #9
                  #3




                  was not shareing

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                  • #10
                    That is not a spiral shaped hole, that is a tear-drop shaped hole.
                    Tom - Spotsylvania, VA

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                    • #11
                      I'm thinking more Yin-Yang than teardrop...

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                      • #12
                        looks like a slot to me .....Bill it looks to me like a round cavity with the set of disks offset to one side....are you sure the outer curving is a change radius? If it is you have to either couple (electronically would be easiest) a rotary table to a mill's table axis....or manually cut it as a whole bunch of facets by move the rotary a degree then the x(or y) axis so many thou, ie make up a table. I've done cams that way, a bit tedious but doable....but my impression from that image is that if it's a spiral at all its very slight??
                        .

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                        • #13
                          Since you've got stacked disks for the Tesla turbine already, I always assumed the way to do it was to rotate the disks relative to each other as they're assembled on the spindle to get the spiral path. Barmen do this trick all the time with napkin stacks. Or to reverse the process if you're drilling all the holes relative to a key position, move the keyway successively in rotation as you're drilling each disk. Worst case I suppose you could fashion a helical EDM electrode and spiral it down through the workpiece - rather like EDMing a thread with a hollow tap.
                          .
                          "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                          • #14
                            Maybe way, way off base here but it puts me in mind of some tri-lobe blower set-ups...

                            http://www.youtube.com/watch?v=QfSJs...eature=related

                            certain designs do spiral/twist helix (could be just me but I find some drawings, like the one shown confusing...which part is spiral and which is not and which part is lobe and which part is "space"...just saying since one or the other could be vastly more difficult to machine)

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                            • #15
                              From the drawing it's kind of hard to determine exactly what the groove is like, but whatever it needs to be a CNC mill can do it.

                              Here's a picture of a spiral groove cut in plastic on a CNC vertical mill.

                              The groove is a semi-circular pocket of varying width with a varying groove radius. I had trouble drawing and programming this to cut efficiently with CAD/CAM. I ended up writing a macro program to do it in the CNC controller. The macro allows varying all the features of the spiral and groove by altering parameters, groove radius, groove width, etc, etc. The cutter was a ball end mill. The mill controller has the axis rotation option.

                              I have no idea how this could be done only with a manual mill and rotary table.

                              This test was cut in plastic to verify the mold cavity was right before cutting in metal.

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