> since we're talking about micrometer-ish (?) mechanical tolerances. Even less than that. Tracks are 100-300 nanometers wide; the head flies about 3-6 nm abov

> since we're talking about micrometer-ish (?) mechanical tolerances. Even less than that. Tracks are 100-300 nanometers wide; the head flies about 3-6 nm above the platter. The actuator mechanism literally locks onto the signal encoded in the magnetic track and follows it as the platter rotates underneath the R/W head.