Abstract: An automatic control for a cotton module builder controls the traversing motor which moves the tamping mechanism in a horizontal direction atop the cotton module builder as well as the packing cylinder which moves a tamping platen up and down. The automatic controller operates continuously in predetermined cycles having adjustable durations. In a first portion of each predetermined cycle the tamping platen is moved up. In a second portion of each predetermined cycle the tamping platen is moved down to compress any cotton within the bin of the cotton module builder located directly below the tamping mechanism. In an overlap portion located about a transition between the first and second portions of each predetermined cycle, the traversing motor is activated to move the tamping mechanism in a predetermined direction for a predetermined distance so as to place the tamping platen over another portion of the bin.