Geometric Symbols & Notation Flashcards

Which GD&T symbol is used to control the orientation of a surface or axis to a datum without controlling its location?

Answer: Parallelism

Parallelism controls orientation (angle = 0°) relative to a datum but does not control the feature's location.

The 'all around' symbol in GD&T is represented by:

Answer: A circle on the bend of the leader line

A circle placed at the bend of the leader line indicates the profile tolerance applies all around the cross-section.

What does the symbol 'Ø' placed before a tolerance value in a feature control frame indicate?

Answer: The tolerance zone is cylindrical

The diameter symbol (Ø) before a tolerance value specifies a cylindrical (3D) tolerance zone rather than two parallel planes.

A free state variation symbol in GD&T is depicted as:

Answer: A circled F

The circled F modifier indicates that the tolerance applies to the part in its free (unrestrained) state.

Which symbol indicates that a feature of size must be at its maximum material condition boundary?

Answer: Circled M

The circled M (MMC modifier) in a feature control frame means the stated tolerance applies when the feature is at its maximum material condition.

The 'between' symbol in GD&T notation is used to indicate:

Answer: A tolerance applies between two specified points

The 'between' symbol (↔) specifies that a tolerance zone is limited to the area between two identified points on a feature.

In a feature control frame, what does a datum reference letter enclosed in a box signify?

Answer: It is a datum feature symbol identifying a reference plane or axis

A letter inside a square box in the feature control frame (or standalone) identifies a datum feature from which measurements are taken.