CNC Machinist III

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.

Skills Matrix Competency

Skills Matrix Competency

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…