Key Points Precision machining is defined by tolerance thresholds, not just equipment. Understanding where the line sits helps you specify correctly from the start Turning, milling, grinding, and Electrical Discharge Machining (EDM) each occupy a distinct role in the process hierarchy, with different cost, time, and geometry implications Sharp internal corners, deep pockets, and unnecessary five-axis features are the fastest ways to add cost and lead time to a machined part Standard Computer Numerical Control (CNC) tolerances run ±0.25 mm (±0.010"); going tighter requires justification because it extends lead time and raises cost The right process match at the design stage prevents expensive rework and keeps your program on schedule What Precision Machining Means The word "precision" gets applied loosely in manufacturing. Shops use it to mean anything from consistent quality to sub-micron control. For engineers specifying parts, that ambiguity costs time and money.