CNC Machining Tolerances & GD&T Guide: ISO 2768, Cost Impact, and Practical Design Rules

Engineering reference for specifying tolerances and geometric dimensioning on CNC machined parts from Olympus Machining LLC, an ITAR-registered precision CNC machine shop in Hanover, Pennsylvania. Covers ISO 2768 general tolerances for medium and fine grades on linear dimensions from 0.5 mm to 1000 mm, GD&T datums and true position with MMC and LMC modifiers, perpendicularity, parallelism, angularity, concentricity, and runout callouts, standard CNC tolerance bands from ±0.005 inch baseline through ±0.0005 inch precision, and the four cost mechanisms: machining time, tooling wear, fixturing complexity, and inspection rigor. Includes DFM rules for tolerance selection, tolerance stack-up guidance for multi-part assemblies, and inspection methods by tolerance band from caliper checks through full CMM GD&T reports. CAGE 9V9P0, CMMC Level 1.