c etc described on the pattern plate 15 as mentioned earlier the grooves 18 have been formed on the outer periphery of the disk cam 2 and to one of said grooves 18 is engaged the end 16 39 of the disk cam spring 16 the control dial 5 can be easily turned by hand against the force of the spring 16 and said engagement helps the pointer needle 14 to determine a position of the stitch patterns a b c etc the operation of the mchanism for selecting the zig zag pattern cams will now be described by turning the control dial 5 the control plate lever 35 having pin 38 engaged with the zig zag pattern cam selection groove 20 formed on the back surface of the disk cam 2 is turned with the shouldered screw 34 as a fulcrum in cooperation with the pin 11 of the pointer needle operation lever 7 further the pin 36 provided on the other end of the lever 35 has been engaged with the elongated groove 37 of the operation plate 32 and the operation plate 32 has been so mounted on the mounting plate 1 as to slide in the elongated grooves 30 31 by means of flanged pins 33 33 therefore if the control dial 5 is turned the operation plate 32 moves in the up and down directions due to the action of the wire spring 42 being guided by the operation plate guide 44 to the operation plate 32 has also been attached the positioning pin.