An apparatus and a system comprise a collet comprising a top portion and a bottom portion. The top portion comprises a threading means. The bottom portion at least comprises means for holding the collet from rotating and means for retaining an end mill. A master comprises a top portion and a bottom portion. The top portion is configured for engagement with a spindle of a milling machine. The bottom portion comprises a threading means for engagement with the threading means of the collet, wherein the master is retained by the spindle and the collet engages and disengages the master by rotation of the spindle. The milling machine operates under computer control during engagement and disengagement of the collet from the master.