Drill chuck arbors have one end which is the taper of the machine. The most common are Morse Tapers for mounting in a drill press spindle or lathe, or NT tapers for mounting in Milling machines. The other end of the arbor is a short taper called a Jacobs Taper that is driven into the taper of the chuck body. The JT taper or Jacobs Taper is the most commonly used taper for mounting a drill chuck. The most common tapers used in Australia are JT2, JT3, JT4 & JT6