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Navy NEC · Engineering

U31A Advanced Machinery Repairman

Current service use not established

This code is listed in the directory. Inclusion alone does not confirm current service use.

A Navy Enlisted Classification: a skill designation sailors hold in addition to their rating. Part of the Machinery Repairman rating

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Overview

An Advanced Machinery Repairman uses basic algebra and trigonometry to manufacture 1-2-3 blocks and spur, helical, bevel, and worm gears from blueprints with engine lathes and universal milling machines. The repairman sharpens and restores drill bits, pump shafts, and milling machine cutters, and understands the setup and operation of vertical turret lathes and horizontal boring machines and the function of electric disintegrators.

Core Skills

  • Blueprint-based gear machining with trigonometric calculations
  • Drill bit and milling cutter restoration
  • Broken fastener removal using electric disintegration
  • Metal identification, testing, and heat treatment

Civilian Career Paths

Career associations are editorial assessments of the cited evidence, not an official crosswalk unless the evidence explicitly says so. O*NET supplies civilian occupation information, not proof of a military match. Related experience does not confer civilian qualifications. Tasks and tools below describe civilian work, not military training.

Machinists

Manufacturing gears and blocks from blueprints using engine lathes, universal milling machines, and machining calculations directly supports precision machinist work.

How to prepare: Prepare a sample machining work plan showing blueprint calculations, lathe or mill setup, and a method for checking finished dimensions.

What the civilian work involves
  • Calculate dimensions or tolerances, using instruments, such as micrometers or vernier calipers.
  • Machine parts to specifications, using machine tools, such as lathes, milling machines, shapers, or grinders.
  • Measure, examine, or test completed units to check for defects and ensure conformance to specifications, using precision instruments, such as micrometers.

Tool and Die Makers

Blueprint-based machining, cutter restoration, and metal heat treatment provide a foundation for making and repairing precision tooling.

How to prepare: Seek supervised shop training in fitting and assembling dies, jigs, and gauges to build on the documented machining and grinding experience.

What the civilian work involves
  • Verify dimensions, alignments, and clearances of finished parts for conformance to specifications, using measuring instruments such as calipers, gauge blocks, micrometers, or dial indicators.
  • Study blueprints, sketches, models, or specifications to plan sequences of operations for fabricating tools, dies, or assemblies.
  • Fit and assemble parts to make, repair, or modify dies, jigs, gauges, and tools, using machine tools, hand tools, or welders.

Notes & Sources

Evidence for this guidance (3 documents)
  1. NAVPERS 18068F Vol II (NEOCS, Jul 2026 edition): NEC U31A

    [1] NEC entry "U31A - Advanced Machinery Repairman"; cached text line 11783; NAVPERS 18068F Vol II, 2026-07 edition

    Supports: Blueprint-based gear machining with trigonometric calculations, Drill bit and milling cutter restoration, Broken fastener removal using electric disintegration, Metal identification, testing, and heat treatment, Machinists (O*NET 51-4041.00), Tool and Die Makers (O*NET 51-4111.00)

  2. O*NET: Machinists

    [2] O*NET 30.3 occupational data

    Supports: Machinists (O*NET 51-4041.00)

  3. O*NET: Tool and Die Makers

    [3] O*NET 30.3 occupational data

    Supports: Tool and Die Makers (O*NET 51-4111.00)

Defense contractor jobs for U31A

Descriptions may be summarized for clarity. Verify all information with your branch career counselor or official military documentation before making career decisions.

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