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Why cant I mate these parts together?

mike_newtonmike_newton Member Posts: 2 EDU
Im currently trying to create a bowl shape using pentagons that are attached at the edges but im unable to get the edges of the bowl to mate together. All 5 polygons mate with no issue to the bottom but I cannot get the sides to mate together. I attached a picture to show you what my issue is.


  • john_mcclaryjohn_mcclary Member, Developers Posts: 2,906 PRO
    Can you link the document?
    It's hard to tell unless you can suppress and change mates to really get into the problem.

    I would suggest using a circle pattern for this anyway, Mate just 2 pieces then pattern around the base. That should be less intense for the mate solving
  • john_mcclaryjohn_mcclary Member, Developers Posts: 2,906 PRO
    edited May 2019
    Actually no need to link, I got the same result.

    there as a problem when you try to link the 3rd pentagon because it is over defining the shape. Most likely due to tolerance issue in parasolid.

    I tried revolute and cylindrical, and both failed.
    But you can bypass this by adding a tangent mate  to the points you show above

    Here is how I would do it with a pattern:

  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 3,269
    I would try to avoid using revolute mates because, in the end, the parts will have no motion. You can use a fasten mate, then expand the mate in the instance list and edit one of the mate connectors to add an angle. Then use circular pattern to finish it off.
  • john_mcclaryjohn_mcclary Member, Developers Posts: 2,906 PRO
    edited May 2019
    I would disagree @NeilCooke
    Every number hand typed in a project reduces the flexibility for future updates, making it less parametric.

    Because this is a polyhedron, your pretty much screwed anyway. But an edit to another shape will always be easier without all that extra fuss typing in the same angle on multiple mate connectors  ;)

    That entire model was only created with 3 hand typed dimensions (inside diameter of the polygon), (polygon side count) and (pattern instance count)

    I never had to know what angle the adjacent faces are :wink: Isn't that why we all use 3D parametric CAD in the first place  o:)<3

    Edit: to clarify, a performance hit towards a computer is better than a performance hit on a slower cad operator.
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