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Internal tapered keyway on CNC lathe?

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  • Internal tapered keyway on CNC lathe?

    Has anyone done this? Keyway inside a tapered bore, too small to get a milling tool inside, so it would have to be slotted.
    I don't want to do it, don't have the kit anyway, but I suppose it could be done and some smart-a**ed tw*t on a non-technical forum has just suggested that's how he would do it (ie on a cnc lathe but being non-specific about method). I doubt he would have a clue how to, but it's set me wondering about the practicality as they're awkward things to do at the best of times.

    Tim

  • #2
    Are you talking about using a CNC lathe as a slotter? I've heard of it being done, never done it myself. I have used a manual lathe with a boring tool set to cut on the 'pull' stroke to cut a blind keyway in a bore. It was kind of fussy, not sure how you'd do it on a CNC as there'd be little 'feel' to the process.

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    • #3
      Piece of piss.
      Did one the other week with a boring tool on the CNC lathe when the spindle didn't start.
      Not pretty but looked a bit slot like before the tip exploded ........
      .

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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      • #4
        Originally posted by rkepler
        Are you talking about using a CNC lathe as a slotter? I've heard of it being done, never done it myself.
        Yes, but particularly as a 'tapered' slotter.

        Tim

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        • #5
          Chuck the engineer that designed the silly thing in the CNC lathe and spin him up until he agrees to redesign it??
          Milton

          "Accuracy is the sum total of your compensating mistakes."

          "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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          • #6
            Doable in a lathe, the CNC gives the taper. Needs spindlelock (or some tack welding).
            Or <whisper> a shaper </whisper>


            Nick

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            • #7
              Or one of these.



              Tool head tilts 30 degree either way just have to do the keyway at 3 o'clock or 9 o'clock instead of at the front 6'oclock position.

              Fifteen minutes to do an infernal spline.



              .
              .

              Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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              • #8
                Originally posted by John Stevenson
                Or one of these.



                Tool head tilts 30 degree either way just have to do the keyway at 3 o'clock or 9 o'clock instead of at the front 6'oclock position.

                Fifteen minutes to do an infernal spline.



                .
                Nice tool, but the question was, has anyone done it on a CNC lathe?

                The hypothetical job was boring the taper in a bronze propeller, maybe 1.5" max bore dia, and then cutting a keyway in the same bore.

                I don't suppose writing the code would be too hard, but how satisfactory would it be? Do many CNC lathes have spindle locks?

                Tim

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                • #9
                  Check out the GTV-42 video at about a minute 40 seconds.

                  http://cubicmachinery.com/videos/

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                  • #10
                    Sir John, who's shop is that machine in? Not yours surely, too much open floor space. It looks too clean to be your shop.
                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #11
                      Probably a piece of cake for these folks:
                      http://www.slatertools.com/video.htm

                      If it works in a straight hole, surely with CNC it'd work in a tapered hole.

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                      • #12
                        Do many CNC lathes have spindle locks?
                        If it does have spindle orientation, it has (at least, it keeps the spindle oriented).

                        If it works in a straight hole, surely with CNC it'd work in a tapered hole.
                        That principle works only with straight holes.


                        Nick

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                        • #13
                          Originally posted by MuellerNick
                          That principle works only with straight holes.

                          Nick
                          Oh..., I didn't know that.

                          But that's not surprising, since I've never really been able to get my brain totally around just how it does work. I can kind of grasp it, but I'd have to see one up close and personal ...I think.

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                          • #14
                            since I've never really been able to get my brain totally around just how it does work.
                            That ain't too complicated. There are two basic types. One where the tool rotates and one where the work rotates. But both work at the same principle:
                            The center of the tool's face is axial with the bore. But the tool's axis is tilted relative to the bore's axis.
                            In a lathe, the work rotates and the tool rotates at its tilted axis (the tool is not driven externally, but by the work). The tilted tool's axis itself does not rotate! Thus, the face of the tool makes a wobbling action at the work's face (a rolling motion) and cuts.
                            In a mill, the work is steady. The tilted tool's axis rotates and the tool itself rotates freely on it's tilted axis. Makes the same wobbling action.
                            It's all the same if you imagine sitting on the work and looking towards the tool.


                            Confusing?

                            Nick

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                            • #15
                              Finally a question I have experience with!!!

                              Yes I have done it with a CNC lathe, Yes it does work (though it was slow going in the 316 i was doing it in) and in bronze it would be a piece of p**s

                              My machine doesn't have a spindle lock but it has a geared headstock and thus in lowest gear didn't shift

                              A couple of years ago when I was pre-cnc I did exactly that job in the boss of a feathering propeller by setting the angle on the compound then using the compound to do the slot winding it in and out (yes I had an aching hand after!).

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