Opening/closing chuck and method of manufacturing fingers

A method of manufacturing fingers configured to slide inside of a guide groove of a body of an opening/closing chuck, and which are slidably supported in directions to approach toward and separate away from each other;

• wherein the fingers each include a pair of overhanging portions configured to project out laterally from a main body portion, outer peripheral surfaces of the overhanging portions are made up from five surfaces including upper surfaces, side surfaces, lower surfaces, first end surfaces, and second end surfaces, and the upper surfaces and the lower surfaces are tapered surfaces configured to come into closer proximity to each other toward the side surfaces;
• the method of manufacturing the fingers comprising a step of applying crowning at intersections of the five surfaces, by performing grinding with respect to the side surfaces and simultaneously performing grinding with respect to the upper surfaces and the lower surfaces, using a single machining tool,
• wherein in the step of applying crowning, in a state where an axis of the machining tool is oriented along a Z direction, the machining tool is caused to circle in an X direction and a Y direction one time around each of the fingers while rotating about the axis.