Why cant I mate these parts together?

mike_newton

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_mcclary

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_mcclary

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:
https://cad.onshape.com/documents/804b885893b0fb97f83c29b4/w/b5281db47b4a42f3d5c519aa/e/b60e6a2371c22a5fddf36643

NeilCooke

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_mcclary

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 Isn't that why we all use 3D parametric CAD in the first place 

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