Obtaining "Equal Curvature" on Spline Ends

Discussion in 'SolidWorks' started by Mike J. Wilson, Feb 4, 2004.

  1. I've always assumed we had to 'manually' create an equal
    curvature condition on the ends of a spline (when made
    tangent to another spline or line) until I ran into this
    message...
    http://www.mikejwilson.com/misc/equal_curvature.jpg

    Is there a way to add this relation (spline constraint) that
    I'm not seeing?

    Thanks!
    Mike Wilson
     
    Mike J. Wilson, Feb 4, 2004
    #1
  2. Mike J. Wilson

    TheTick Guest

    A glimmer of (false?) hope, perhaps? I've been waiting and whining
    for SW to improve curvature control of splines. I see nothing in the
    help or API help for SW2004.



    to add this relation (spline constraint) that
     
    TheTick, Feb 4, 2004
    #2
  3. Mike J. Wilson

    Zander Guest

    Zander, Feb 4, 2004
    #3
  4. Here is a simplified way...

    *) Start new 2D sketch
    *) Draw two horizontal lines, one on the upper right
    of your screen, the other on the lower left.
    *) CTRL-select each and hit "Fit Spline". Use Constrained.
    *) Right-click the newly created spline and select "Split
    Entities" and try splitting the spline.

    That's when the message pops up.

    Mike Wilson
     
    Mike J. Wilson, Feb 4, 2004
    #4

  5. Cool! I had never played with fit splines before. It looks like it will be
    very useful, providing a workaround for the lack of curvature control.
    Strange that the help doesn't point out that the spline matches the
    curvature of the underlying geometry, whether it's a line, an arc or another
    spline.

    Jerry Steiger
    Tripod Data Systems
     
    Jerry Steiger, Feb 4, 2004
    #5
  6. Because they cannot guarantee it. All "fit spline" does is to draw a new
    spline from "enough" points located on the underlying geometry such that the
    distance between the spline and the line/arcs/spline is withing the given
    tolerance.
    Do a "simplify spline" with a 0 tolerance to see the spline control points.
    Remember that splines are polynomial functions, so they cannot have a
    constant curvature like a circle (ok, it's easier with a line...)
    But you are correct, SolidWorks/D-Cubed could "easily" add start/end
    tangency to splines.

    FYI, we will "soon" release an addin that does "fit-spline" automatically to
    all the chains in a sketch, for example to an "exploded" text or to an
    imported dxf...
     
    Philippe Guglielmetti, Feb 5, 2004
    #6
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