Buttonholer

A buttonholer is an attachment for a sewing machine which automates the side-to-side and forwards-and-backwards motions involved in sewing a buttonhole.

Most modern sewing machines have this function built in, but many older machines do not, and straight stitch machines cannot sew a zigzag stitch with which buttonholes are constructed. A buttonholer attachment can create buttonholes from any sewing machine capable of making a lock stitch. (That is not to say, however, that some industrial buttonhole machines cannot employ a chain stitch, especially to create the purl when making keyhole buttonholes).