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    Helix Geometry Question

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    • Dave RD Offline
      Dave R
      last edited by

      So I'm trying to draw a helix that transitions nicely and smoothly from a vertical straight line, gets larger and then smaller and transitions back into a vertical line. Using either curverMaker or DrawHelix, I can draw a single turn helix that would seem to suit for half the desired helix but when copied and flipped, there is an evident kink as seen in the middle, end on view and on the right. Ideally I want to end up with a single turn from start to finish. i can get that by splitting the helix at the right location and deleting what I don't need. I still end up with the kink. Additionally, there isn't a pleasant transition between the helix and a straight line.


      http://farm7.static.flickr.com/6135/5964595555_167922bc9f_z.jpg

      What I'm wondering about is a good way to eliminate the kink so the helix is fair all the way along its length. The other thing then is a good way to make the transition from helix to vertical line. I'm thinking there must be a an easy way but I'm missing it. Probably been looking at it too long.

      Etaoin Shrdlu

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      • J Offline
        jdadesignstudio
        last edited by

        Dave-Is this what you are looking for? I think I made mine wider in the middle differently than you did, but I just used bezier spline to create smoother transitions and deleted the old pieces...If it helps I dont mind giving you the SU file.


        spiral.jpg


        middle joint


        vertical joint

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        • Dave RD Offline
          Dave R
          last edited by

          Thanks Jon.

          That might be it although it looks like too many turns. I was just waiting for SU to open and saw your post. I was thinking that I might have to do as you did. I'll give it a shot.

          Thanks.

          Dave

          Etaoin Shrdlu

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          (THERE'S NO PLACE LIKE)

          G28 X0.0 Y0.0 Z0.0

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          • J Offline
            jdadesignstudio
            last edited by

            No problem-if you have trouble you could shoot me the SU file and I could give it a go too. The best curve I was getting was by using classic bezier curve, making the endpoints pretty close to the intersection (but about equal distance away from the intersection), and then just make one control point at the intersection itself.

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            • Wo3DanW Offline
              Wo3Dan
              last edited by

              Hi Dave, here's a manually drawn smooth/stretched helix going from vertical > large radius > vertical. The scenes go through the technique used with basic SU.


              smooth helix with various radii running from vertical to vertical

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              • Dave RD Offline
                Dave R
                last edited by

                Gerrit,

                Thank you, my friend. I don't know why I didn't think of that. I was so fixated on drawing it in 3D from the beginning. Your way makes perfect sense.

                Etaoin Shrdlu

                %

                (THERE'S NO PLACE LIKE)

                G28 X0.0 Y0.0 Z0.0

                M30

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                • daleD Offline
                  dale
                  last edited by

                  Gerrit,
                  That is a really slick solution.
                  It amazes me at how the generic toolset can accomplish just about anything you want.
                  Thanks, a very insightful set of postings.

                  Just monkeying around....like Monsanto

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