GD&T Geometric Symbols & Notation 2 — Questions and Answers
Question 1: Which GD&T symbol is used to control the orientation of a surface or axis to a datum without controlling its location?
- Parallelism (Correct answer)
- Position
- Concentricity
- Profile of a Surface
Correct answer: Parallelism
Parallelism controls orientation (angle = 0°) relative to a datum but does not control the feature's location.
Question 2: The 'all around' symbol in GD&T is represented by:
- A circle on the bend of the leader line (Correct answer)
- Two concentric circles
- A flag on the leader line
- An asterisk next to the tolerance value
Correct 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.
Question 3: What does the symbol 'Ø' placed before a tolerance value in a feature control frame indicate?
- The tolerance zone is cylindrical (Correct answer)
- The feature is a hole
- The tolerance applies to diameter measurement
- The feature requires a circularity check
Correct 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.
Question 4: A free state variation symbol in GD&T is depicted as:
- A circled F (Correct answer)
- A circled M
- A circled L
- A circled P
Correct answer: A circled F
The circled F modifier indicates that the tolerance applies to the part in its free (unrestrained) state.
Question 5: Which symbol indicates that a feature of size must be at its maximum material condition boundary?
- Circled M (Correct answer)
- Circled L
- Circled F
- Circled S
Correct 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.
Question 6: The 'between' symbol in GD&T notation is used to indicate:
- A tolerance applies between two specified points (Correct answer)
- A tolerance applies to the entire surface
- A datum target area
- A simultaneous requirement
Correct 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.
Question 7: In a feature control frame, what does a datum reference letter enclosed in a box signify?
- It is a datum feature symbol identifying a reference plane or axis (Correct answer)
- It is a tolerance value modifier
- It represents a basic dimension
- It indicates a non-mandatory reference
Correct 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.
GD&T Geometric Symbols & Notation 2
Which GD&T symbol is used to control the orientation of a surface or axis to a datum without controlling its location?