Interview OS
Back to CAD & Mechanical Design

Library

GD&T & tolerancing

Communicate allowable variation.

Tolerancing

Overview

Geometric Dimensioning and Tolerancing (GD&T) is a symbolic language for specifying allowable variation in form, orientation, and position. It communicates design intent unambiguously so parts fit and function as intended.

How it works

Tolerancing
DatumFeatureToleranceOutputReferencesdatumsCalloutsymbolZone⌀0.1Drawing
ClientServiceEdgeData

Step by step, with examples

  1. 1

    References

    • Set the datum frame A-B-C.
  2. 2

    Callout

    • Position, flatness, and more.
  3. 3

    Zone

    • Define the allowable zone.
  4. 4

    Drawing

    • Produce an inspectable spec.
    • Example: ASME Y14.5

Overview

Geometric Dimensioning & Tolerancing (ASME Y14.5) defines feature relationships with datums and tolerance zones for function and inspection.

Key idea

Tolerance the function, not the convenience — over-tight tolerances cost money.

Common pitfalls

  • No datum scheme
  • Tolerance stack-up ignored
  • Bonus tolerance misunderstood

Where this content comes from

For full transparency, this content is curated and verified from these sources:

ASME Y14.5 GD&T standardParametric CAD vendor documentationOppZen-authored CAD design guides