Abstract: An apparatus for casting polymer threads (32) in a nut cavity (14) complementary to the threads (44) of a casting screw (42) to minimize the formation of air pockets and air bubbles in the polymer threads. The cavity (14) of the nut (12) has a diameter larger than the diameter of the casting screw (42). The threads (32) of the nut (12) are formed in a polymer (30) which is dispensed into the nut cavity (14) and which cures around the threads (44) of the casting screw (42) after the screw is inserted into the cavity of the nut. The nut casting apparatus (10) includes support member (54) for closing the bottom of the cavity (14), and for containing the polymer (30) therein.