Abstract: A dividing head assembly comprises concentric outer and inner primary and secondary shafts journalled in a body member having a base for mounting the assembly on a machine tool bed in juxtaposition to a cutter. The inner shaft is coupled for rotation with the outer shaft and is axially slidably mounted in the outer shaft. The inner shaft has a workpiece holder at one end and a collar at the other end formed with a master thread and/or a master cam profile. A gear drive is provided for rotating the shafts, and the body member carries a follower for engaging the respective cam profile or master thread so that on rotation of the drive means the workpiece holder is provided with controlled rotation accompanied by axial movement thereof governed by the cam profile or master thread, for screw or cam forming a workpiece.