A helical coil compression spring is needed for food service machinery. The load varies from a minimum of 4 lbf to a maximum of 18 lbf. The spring rate k is to be 9.5 lbf/in. The outside diameter of the spring cannot exceed 2 ½ in. The spring maker has available suitable dies for drawing 0.080-, 0.0915-, 0.1055-, and 0.1205-in-diameter wire. Using a fatigue design factor nf of 1.5, and the Gerber-Zimmerli fatigue-failure criterion, design a suitable spring.