11 Replies Latest reply on Nov 30, 2007 3:30 PM by Daniel Stroschine

    Curve Through XYZ Question

    Daniel Stroschine
      For a curve through XYZ points does SW use a cubic spline tointerpolate between the points or some other method?
      Thanks, Dan
        • Curve Through XYZ Question
          Steve Calvert
          Dan, it looks to be just points, no poles to edit just the point insertion box. Are you looking for something different? This is a good way to create known geometery but I fail to see its use for new stuff. I'd like to see a change to the create of the spline, maybe instead of a spline we could get just straight lines between the points. Then we could use this for tube bending and routing and be able to get a set points for the tube bending machine.

          Steve
            • Curve Through XYZ Question
              Daniel Stroschine
              Steve,
              I work for an optics company and need to create models/drawings foraspheric curves. Ideally I would have a curve controlled by theequation but since that is not available in SW I have to resort tohome-grown macros that dump out a series of points that are thenused to create the curve using the XYZ points.

              But I have had issues with the accuracy of the reproduction of thesurface and I am trying to work out how many points I need to use.I want to keep them down to a minimum because if I want to move thecurve after it is created I have to add/subtract the amount I wantto move it to/from the appropriate axis, this is a pain even whenthere are small number of points.

              I agree that having control over the interpolation would be nice,but for now I'll settle for just knowing what it is.

              Dan
                • Curve Through XYZ Question
                  Steve Calvert
                  Is the cross section of the lens the same (although thinner) with the aspheric lens? If it is, why couldn't you use a surface sweep? I would think that with the number of poles defining the spline you could have mistakes in constant thickness, so you would keep them to a minimum.

                  Please show us when you get one finished, this is interesting stuff. Sure beats the hell out of breaking an edge to get a flange.

                  Steve
                    • Curve Through XYZ Question
                      Daniel Stroschine
                      Steve, These are generally not a constant thickness. There are evencases where there is an inflection point in the curve. If I wereconfident in the interpolation between my control points I guess aloft would work too but right now I don't have that confidence, andI haven't had time to do a # of points vs. accuracy test. I canlive with an error of a couple of microns, but not more than that.I can get this accuracy with other programs (MDT and Inventor) butI don't have enough experience with SW to be confident. I'veattached an example lens that uses the following points to createthe aspheric curve:
                      0.0000 0.0000 0.00.0520 1.0000 0.00.1975 2.0000 0.00.4126 3.00000.00.6748 4.0000 0.00.9675 5.0000 0.01.2798 6.0000 0.01.6043 7.00000.01.9336 8.0000 0.02.2567 9.0000 0.02.5538 10.0000 0.02.788611.0000 0.02.8980 12.0000 0.0
                • Curve Through XYZ Question
                  Jennifer Zuba
                  Dan,

                  I too work for an optics company and have had the same issues you are experiencing with aspheric shapes. The best solution I have come up with is to create the aspheric portions of the lens in a 3rd party program like (I use SurfX3D) in which you can create surfaces from equations, then save them as a .dxf and import them into Solidworks as a part-in part. Hope this helps.