a socket 96 located in the frame 38 and includes another semispherical projection 97 which rides in a socket 100 located in a flanged portion 102 of member 22 the coupling 58 is held in an assembled relationship with the frame 38 and flanged portion 102 of member 22 by springs 104 and 106 which bear against protuberances 108 and 110 respectively on the coupling as shown the springs are integral parts of a bracket 108 which is secured to member 22 by a screw 110 and threaded fastener 112 needle bar 32 is vertically reciprocated as noted that is by the crank 28 and a needle 112 at the lower end of the bar is moved to perform a sewing operation at the same time an oscillating motion is imparted to the frame 38 and therefor also to needle 112 by a link 114 which is connected to the frame at 116 and is longitudinally reciprocated by the driving mechanism of the machine in customary fashion the leaf spring 54 and plastic coupling 58 determine the particular manner in which the frame and needle move the frame pivots while the spring flexes about a transverse axis in the spring substantially in the plane of the center line of the needle bar in addition the upper portion of the frame is caused to follow a curved path 117 in a more or less horizontal plane by the coupling 58 and the leaf spring twists slightly to accommodate this motion the center line distance between the sockets 96 and 100 wherein the semi spherical projections 94 and 97 of the plastic coupling ride is such as to provide between the extreme points of travel 118 and 120 of the needle a path 122 concentric with the curvature of the rotary.