CNC Machinist III

Job Description

Job Description

Department: CNC Mill or Lathes

Position Title: CNC Machinist III

FLSA:
· Non-Exempt / Hourly ·

Reports to:
Plant Manager

The CNC Machinist III is the shop's most capable and self-directed machinist — the person who takes the difficult job, the tight tolerance, the new part, or the problem machine and returns it to production without hand-holding. The role owns independent setup and prove-out across all assigned work centers, dimensional quality at the machine, and the development of less-experienced machinists. The Machinist III works from prints and models rather than proven paperwork alone, authors and corrects programs at the CNC control, and makes the process decisions — tooling, work holding, sequence, speeds and feeds — rather than executing someone else's.

This is the top rung of the machinist ladder and the primary feeder into the programming track; proficiency is measured against the Machinist Skills Matrix using the 0–4 Skill Level Key.

• Perform complete setups from scratch on all assigned work centers — work holding, tooling, offsets, program load, and first-piece qualification — without supervision.
• Select and document tooling, insert grade, work holding, and operation sequence for new or problem parts.
• Prove out new and revised programs at the control, correcting toolpaths, feeds, speeds and offsets to bring parts into tolerance; run production to print and router, holding dimensional quality, surface finish, and cycle time across the shift.
• Write, edit, and optimize G-code and M-code at the CNC control, including subprograms, canned cycles, and parametric / macro programming for part families.
• Own dimensional quality at the machine using micrometers, bore gauges, indicators, height and thread gauges, surface plate, and optical comparator.
• Interpret prints and models including GD&T datums, feature control frames, true position, and tolerance stack-up; support first-article inspection, interpret CMM reports, translate findings into corrections, and contain suspect material per quality procedure.
• Diagnose and correct chatter, poor finish, dimensional drift, tool wear and breakage, and control alarms; separate process problems from machine problems and partner with maintenance on the latter. Perform operator-level preventive maintenance — way lube, coolant concentration, chip and filter management, machine cleanliness.
• Train and mentor Machinist I and II personnel, sign off competency as authorized, and author or correct setup sheets so setups are repeatable by others.
• Drive cycle-time and scrap reduction, tooling standardization, and 5S; maintain accurate labor, quantity, and scrap reporting.
• Follow and enforce all safety rules, lockout/tagout, machine guarding, and PPE requirements; correct unsafe conditions and report near-misses.

The competencies below are required in this role. Proficiency expectations for each are defined and assessed in the Machinist Skills Matrix.

• Safety & shop practices
• Speeds, feeds & chip load
• Shop math & trigonometry
• CNC programming — control level
• Print reading & blueprint interpretation
• Macros / parametric programming
• GD&T & tolerance interpretation
• Advanced CNC (multi-axis, mill-turn)
• Measurement & inspection
• Prove-out & first-article support
• Materials & machinability
• Troubleshooting & problem solving
• Manual machining (lathe / mill / grind)
• Machine technology — work centers
• CNC machine operation
• Documentation & setup sheets
• CNC setup
• Training & mentoring
• Workholding & fixturing
• Continuous improvement / scrap reduction
• Tooling & insert selection

Equipment Proficiency

Required — Setup 3–4 / Run 4: CNC lathes, including live-tool and bar-fed turning centers; CNC vertical machining centers; CNC horizontal machining centers.

Development target — Setup 2 / Run 3: CNC mill-turn and multi-axis turning centers; twin-spindle lathes. Active development on at least one mill-turn platform is expected.

As assigned: CNC OD grinding and CNC gear equipment; manual lathes and mills, grinders, shapers, saws, presses, and deburr stations for rework and fixture work. Ratings apply to the work centers listed on the machinist’s qualification card; machines not on the card are outside the scope of the title u