The permissible range of variation in a part dimension, defined as the difference between upper and lower limit.
Tolerance specifies how much a dimension may deviate from its nominal value. It is the algebraic difference between the maximum and minimum limits. Tighter tolerances increase manufacturing cost exponentially. Standard IT grades (ISO 286) range from IT01 (precision) to IT18 (rough).
In FDM/FFF printing, typical achievable tolerance is ±0.2–0.5 mm depending on axis and material. Design for ±0.3 mm unless calibrated. Measure actual printer output before designing mating parts.
Specifying unnecessarily tight tolerances on printed parts forces post-processing. Anisotropy means Z-axis tolerance is typically worse than XY. Always verify with calipers after a test print before committing to a final design.
Related terms: Clearance Fit, Interference Fit, Dimensional Accuracy, GD&T (Geometric Dimensioning & Tolerancing)
| Field | engineering |
|---|---|
| Also called | dimensional tolerance, engineering tolerance |
| Source | EDi Brain: rules-core |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert