A threaded fastener includes a nut forming a threaded center hole that defines a rotational axis. The threaded fastener also includes a plurality of spring plungers affixed to the nut, each having a shaft that is aligned parallel to the rotational axis. The threaded fastener also includes a positioner forming (i) an unthreaded center hole that is coaxial with the threaded center hole and (ii) a plurality of recesses facing the spring plungers. As the nut is torqued against the positioner on a threaded spindle, the spring plungers repeatedly engage and disengage the recesses as the nut rotates with respect to the positioner. The recesses are shaped such that positioner converts the applied torque into a linear force that compresses the spring plungers, thereby locking the threads of the nut against the threads of the spindle.