Buttonhole bar tacker sewing machine with a device for controlling the

Abstract

There is disclosed a buttonhole bar tacker sewing machine with a device for controlling the length of the buttonhole terminated by a wedge bar tack, the machine having a support plate for the workpiece and control members for exerting a reverse motion in the direction of the longitudinal axis of the buttonhole. The control device comprises a first cam, a cam for forming a wedge bar tack and at least one further cam coupled in its motion with the first cam for bar tacking the eye of the buttonhole. The further cam for bar tacking the wedge bar tack of the buttonhole is arranged reversibly rotatable about its axis of rotation and adjustable in its angular position and adjustable relative to the first cam and is further reversibly coupled in its motion with the reversible motion of the support plate in the direction of the longitudinal axis of the buttonhole. The further cam is provided with a cam groove consisting of a section having a symmetrical course relative to the axis of rotation of the cam for bar tacking the wedge bar tack of the buttonhole, and a further section consisting of two parts mutually offset as to their heights, a roller mounted on a displaceable pin being inserted into said cam groove, said roller following in dependence upon its height defined position by the position of the displaceable pin the path of either one or the other of two mutually offset parts as to the height of the cam groove and following independently of the height position the path of symmetrical sections of the cam groove, each of said two height positions of the displaceable pin being defined by the angular position of the said further cam coupled in its motion with the first cam.