A machine for sewing together two workpiece parts having edges of equal or unequal length by using a bead seam, especially for joining together the edge of a vamp and the shorter edge of a plug of a true moccasin shoe, so that the length of the plug matches that of the longer edge of the vamp, in only one operation. The bead seam forming device essentially consists of a folding finger acting in front of the needle of the sewing machine and in synchronous driving connection with the needle; several machines are described which are provided with different bead seam forming devices.