Federal job category 3400 covers skilled trades focused on machining and fabricating metal parts using conventional and computer numerical control (CNC) equipment. These roles include Machinists, Machine Tool Operators, and Toolmakers who shape, fit, and finish components for everything from aircraft and vehicles to specialized instruments and mechanical systems. Employees in this category work with lathes, milling machines, drill presses, and grinders to produce precision parts from raw stock or repair worn components. The work demands a deep understanding of machining processes, blueprint reading, and material properties.

Most positions fall under the Federal Wage System and are hands-on, often located in military depots, federal workshops, or research facilities. Workers plan machining sequences, set up equipment, and perform quality checks to ensure parts meet exact specifications. Whether fabricating prototypes or restoring mission-critical hardware, these roles require technical skill, attention to detail, and problem-solving ability. GS-3400 positions are essential to maintaining and advancing the mechanical backbone of federal operations.