3 Replies Latest reply on Apr 11, 2008 1:13 PM by 1-9C36HC

    Best way to creating symmetric Spline section sketches?

    fusu thao
      Hey everyone,

      I looking for best practice tips on creating symmetrical 2d spline sketches for loft sections. I've seen some seminars that say we shouldn't sketch half a section and then mirror because you'll get that centerline split in the surface; although this is the quickest.

      Instead sketch the complete section/loop and make the spline points symmetrical; however, how do you maintain that the control handles and curvature are symmetrical when moving the control handles or polygons/triangles? Only the points are symmetrical and you can reset the handles but that gets tedious and can result in undesired spline design.

      Please advise.

      Thanks.
        • Best way to creating symmetric Spline section sketches?
          Charles Culp
          I typically accomplish this by creating perpendicular lines off of the centerline, then making them colinear and equal in length. This is not nessisarily the easiest way.
          • Best way to creating symmetric Spline section sketches?
            Matt Lombard
            getting the split down the middle of a symmetric part is not the end of the world as long as the curvature across it is good after the mirror.

            You can also draw a spline and mirror it, although this will also give you a split.

            Or you can draw a single spline with a centerline and create symmetric relations between the interior spline points. This works great, but its tedious. One of the downsides to this is that you cannot make the spline handles symmetrical. To get past that you have to make construction lines tangent to the ends of the spline and control the construction lines. For the magnitude of the handles you might want to set up link values.

            The thing with SW is that there are a lot of ways to do things, but none of the ways gives you everything you want.
            • Best way to creating symmetric Spline section sketches?
              I'm not following. In 2008, if you mirror a 2D sketch spline, ALL attributes of the spline, including vector and magnitude of the handles should mirror.

              With that said, my opinion is that for symmetrical product design shapes, you should only be modeling half and then mirroring toward the end of your feature tree. this makes for less features (work) and a more robust model.