Plane tangent to an ellipsoid

[zakk]

I am modelling a vessel head consisting of a 2:1 ellipisoidal head. I need to place a thru-hole at the top of the crown.

I do not wish to use a Parallel Plane that is offset a discrete distance from the knuckle/flange point of tangency because if I later change the size of the Head, the offset will no longer hold the plane tangent to the top of the head.

How do I place a plane tangent to the top of the crown that is also anchored to the top of the crown?

 

[CorBlimeyLimey]

Why create a new plane? Use the existing plane at the knuckle/flange & cut the hole "through all" in the crown direction.


Making the best use of this Forum. faq559-716
How to get answers to your SW questions. faq559-1091
Helpful SW websites every user should be aware of. faq559-520