The roller nest mill cutter is a special tool used when forming the roller nest in a roller bearing. This paper presents a geometric solution for two of the tools' main components. These components are the ball part of the mill cutter, located at the tip of the minimal circumscribed cylindrical shank, and the conical surface between the lubricating oil slot cutter and the roller nest cutter. This paper gives the computations required to provide a reference for the assessment of the roller nest mill cutter.