pin 54 is moved closer to the shaft 16 causing the needle to be moved to the left in fig1 this needle position can then be used for straight stitches or constitute a width limit for the zigzag stitches of the machine the zigzag seam sewn by the machine when set as in fig5 is symmetrical around a center line in the stitch field and is obtained from a cam disk 65 see fig2 in the unit this disk has cams all around which lift the cam follower 33 so that the guide every second revolution of the machine is in the solid line position as to fig5 and in other revolutions in the dashed line position the pin 54 will then swing between the outer positions i e make an oscillatory movement in fig5 which movement is passed on to the needle bar by the bar 46 by means of the knob 47 and the curve 48 the amplitude of the movement can be set on an arbitrary value so that a picture according to fig6 is obtained when the knob is rotated from the maximum value of zigzag to zero during this setting movement of the knob 47 the slide 51 is moved from the position in fig5 to that in fig4 and the said oscillatory movement of the pin 54 is decreased successively when sewing a zigzag.