CNC Machining Tolerances: What Is Actually Achievable

Every machined part has tolerances - the allowable variation from the nominal dimension. What is actually achievable depends on the process, the material, and the geometry.

Standard Tolerances

• Standard CNC machining - typically ±0.005 in (±0.13 mm) for general features
• Tight tolerance work - ±0.001 in (±0.025 mm) or better for critical bores and fits
• Grinding - ±0.0001 in (±0.0025 mm) for the highest precision

The Tolerance-Cost Relationship

Every step tighter in tolerance adds setup time, inspection time, and cost. The single most expensive habit on a drawing is over-tolerancing - specifying tight tolerances on features that do not need them.

For the full tolerance guide, read CNC Machining Tolerances.

IsoCNC holds tight tolerances and verifies every dimension with CMM inspection.