I have fabricated a cone, I need to create drawing views for fab and machining. I have made this drawing dimensioned the fabrication views, then on page 2 I want to detail the machining part

of the drawing. I produced both fab and machining configurations. But when I get to dimension the material to machine from the part, I try to use the plane that is constructed in the cone.

I can't constrain a phantom line to dimension to on the plane. Any help would be appreciated.