An improved end-working attachment (30) for a screw machine or a rotary transfer machine is particularly suited for use in rolling threads on a workpiece. The attachment broadly comprises: a slide base (31) having an axis (y-y); at least two members (32, 32) mounted on the slide base for sliding movement in a radial direction toward and away from the slide base axis; a tool, such as a thread die (33), on each member; an infeed mechanism (34) for selectively causing the slide members to move toward the slide base axis such that said tools will engage said workpiece; and a return mechanism (35) for urging the members to move away from the slide base axis.