My assembly has two spherical surfaces in contact with each other as shown in the screenshot of a section view below.  I would like to be able to mate the top part to the middle part by keeping the spherical surfaces coincident with each other so the top part can tilt back and forth.

Currently, I have it held in place by a combination of two width mates and a tangent mate between the top edge of the of the middle part's spherical surface and the spherical surface of the top part.  I thought I would be able to use a combination of tangent mates to ensure that the two surfaces remain in contact, but merely suppressing the width mates results in the top part moving to a strange orientation.  Adding a mate between the bottom edge of the top part's spherical surface and the spherical surface of the middle part only results in an even more strange orientation.

Ultimately, I wish I could simply create a coincident mate between the two spherical surfaces.  Can anyone explain the best way to accomplish this?

Edit:

Forgot the screenshot.  Sorry!

Message was edited by: Tim Lewis