Input: pink crank.
Middle point of blue slider draws intersection (green ellipse) of yellow cone and a plane. The plane is parallel to the face of the green disk, tight angle of which is adjustable.
Red spring forces the blue slider toward the disk, maintains the contact between left point of the blue slider and the disk.
If the left point is of a sphere, its radius should be as small as possible to reduce error of the intersection.
Axis of the cone and rotary axis of the pink crank are in line.
Line that connects two points of the blue slider is parallel to rotary axis of the pink crank.
Adjust tilt angle of the green disk to get various intersections.