Abstract: Immediately behind a tap of an automatic threading machine to which nuts or like pieces are fed in succession, is a straight portion of a cast-off sheet coaxial with the tap and which is followed by an inclined portion including an obtuse angle with the straight portion. Another straight portion parallel to the first includes an obtuse angle with the inclined portion and guide passages are formed around the inclined portion and the final parallel portion in a head which is rotated to drive the tap. The nuts thus pass over the tap and the cast-off shaft and axial play of the cast-off shaft is minimized.