A tilt-control assembly for use with an operating mechanism of an architectural-structure covering is disclosed. The tilt-control assembly includes a limiter having an external screw thread and a ball operatively associated with the screw threads so that rotation of the limiter moves the ball relative to the limiter. The screw threads may include variable pitch threads. For example, the screw thread may include a middle thread pitch in a middle portion of the screw thread and an end thread pitch adjacent to the ends of the screw thread, the middle thread pitch being smaller than the end thread pitch. In addition, the limiter and/or screw threads may include a variable diameter. The ball may be positioned within a groove including a contoured surface that substantially corresponds to the variable diameter. The ends of the screw thread may include substantially spherically shaped end portions for receiving the ball therein.