Parametric curve problems

james_gladden690

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?

eric_pesty

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.

eric_pesty

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

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

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.