Tag: GDT

GD&T (ASME Y14.5)

GD&T Reference Guide (ASME Y14.5)

Geometric Dimensioning and Tolerancing symbols and definitions.

1. FORM (No Datums)

Symbol Name & Definition
Straightness Symbol Straightness: 2D straightness of a line element.
Flatness Symbol Flatness: Surface must lie between two parallel planes.
Circularity Symbol Circularity: Roundness of a 2D cross-section.
Cylindricity Symbol Cylindricity: Roundness + Straightness of a 3D cylinder.

2. ORIENTATION (Datums Required)

Perpendicularity Symbol Perpendicularity: 90° to datum.
Parallelism Symbol Parallelism: Equidistant from datum.
Angularity Symbol Angularity: Specific angle to datum.

3. LOCATION (Datums Required)

Position Symbol Position: Center location relative to True Position.
Concentricity Symbol Concentricity: Median points on datum axis.
Symmetry Symbol Symmetry: Features equally disposed about center.

4. RUNOUT & PROFILE

Circular Runout Symbol Circular Runout: 2D wobble.
Total Runout Symbol Total Runout: 3D wobble (surface).
Profile of Line Symbol Profile of Line: 2D outline control.
Profile of Surface Symbol Profile of Surface: 3D surface control.