The taper attachment is used for turning and boring tapers. It is bolted to the back of the carriage saddle. In operation, it is connected to the cross-slide so that it moves the cross-slide laterally as the carriage moves longitudinally. This action causes the cutting tool to move at an angle to the axis of the workpiece to produce a taper.
The angle of the desired taper is set on the guide bar of the attachment, and the guide bar support is clamped to the lathe bed. Since the cross-slide is connected to a shoe that slides on this guide bar, the tool follows along a line that is parallel to the guide bar and hence at an angle to the workpiece axis corresponding to the desired taper.