JPS6141594B

A method for the formation of an overcast seam by means of a zig-zag sewing machine. After the formation of the first looping of needle and looper thread in a first overstitch position of a needle bar the needle thread is loosened and the needle bar moves into a second overstitch position, in which a further thread looping takes place. After the formation of at least one straight stitch in the second overstitch position, the joining thread between the first two thread looping is drawn out, forming a loop in the first overstitch position, the needle pierces into the loop, after which it is released. The seam thus formed is a firm joining seam by which the sewing material is not gathered between the thread loopings. The method is carried out on a device which comprises an oversewing tongue to which is assigned, in order to obtain two successive motional phases, a starting handle arranged in the swinging path of the needle bar, and a starting handle arranged in the axial path of motion, for the first overstitch position and into whose path of motion protrudes a loop stripper. The needle bar thus controls the drawing out and casting off of the joining thread between the first two thread loopings.