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Parametric curve problems

james_gladden690
james_gladden690 Member Posts: 4 EDU
in Community Support

Hello,

I am attempting to use the parametric curve feature script tool found here:
https://cad.onshape.com/documents/578ff8b3e4b0e65410fcfda3/w/d33395f174e5b38f4abd6097/e/0c17de6a800d4aed83de417f

I am successful in creating the desired curve with the tool. However, using the result causes problems. Here's a link to my work:
https://cad.onshape.com/documents/c8e9434cd88794051af5d3c9/w/227e1aa0c8cd2ad85665c29f/e/258a0c08b7206a218b65d2cf?renderMode=0&uiState=672e4649df2bf93083a2af6e

I did the following:

  1. Created the curve
  2. Created a sketch and used the "use" tool to copy the curve onto my sketch
  3. Added a construction line coincident to one end of the curve.

So far so good. However, I now encounter problems:

  1. If I attempt to add a constraint making the construction line normal to the end of the curve, an error results. Interestingly, If I add another line coincident and tangent to the end of the curve, and then constrain it as perpendicular to the construction line, that works.
  2. If I attempt to make the curve an element in a circular pattern I cannot select it.

Any ideas what is going on here?

Best Answer

  • eric_pesty
    eric_pesty Member, pcbaevp Posts: 2,885 PRO
    Answer ✓

    Spline patterns aren't supported in sketches, for some reason (the "used" curve is created as a spline).

    I would pattern the curve before the sketch, or even better it's always better if you can do the patterning later on features instead of in the sketch.

Answers

  • eric_pesty
    eric_pesty Member, pcbaevp Posts: 2,885 PRO
    Answer ✓

    Spline patterns aren't supported in sketches, for some reason (the "used" curve is created as a spline).

    I would pattern the curve before the sketch, or even better it's always better if you can do the patterning later on features instead of in the sketch.

  • james_gladden690
    james_gladden690 Member Posts: 4 EDU

    Thank you for your helpful response. It explains why I can't pattern the spline - although I remain curious as to why I can constrain a line to be tangent to the end of spline but not normal.

    My objective is to create a plate with three spiral slots - each 120 degrees in length and spaced 120 degrees apart. I planned to start with the splined curve (as a construction line), offset it in both direction to create the edges of the slot, and then cap the ends with curves.

    Is there a better way to approach the problem?

  • eric_pesty
    eric_pesty Member, pcbaevp Posts: 2,885 PRO

    Use the slot tool, that should work fine…
    Otherwise you could use the curve to do an "thin" extrude and add fillets at the ends. Either way should work.

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