GD&T - Geometric Dimensioning and Tolerancing Datum Reference Frames Questions and Answers

Question 1

In a standard Datum Reference Frame (DRF), what is the minimum number of points of contact required for the primary datum feature to constrain the part?

Accepted Answer

Three points

Answer

One point

Answer

Two points

Answer

Four points

Question 2

A drafter specifies two separate, coplanar surfaces on a part as a single primary datum feature. Which of the following geometric tolerances is best suited to control the relationship between these two surfaces?

Accepted Answer

Profile of a Surface

Answer

Flatness

Answer

Parallelism

Answer

Position

Question 3

Which of the following best describes the relationship between a 'datum feature' and a 'datum'?

Accepted Answer

A datum feature is a tangible surface on the part, while a datum is the theoretically exact point, axis, or plane derived from it.

Answer

They are identical and the terms are used interchangeably.

Answer

A datum is a real, tangible feature on the part, while a datum feature is the theoretical plane derived from it.

Answer

A datum feature is only used for primary datums, while a datum is used for secondary and tertiary.

Question 4

An engineering drawing shows a feature control frame referencing datums in the order |A|B|C|. What does this order of precedence signify during inspection?

Accepted Answer

The part must first be constrained by the simulator for datum A, then B, and finally C.

Answer

The part can be inspected against the datums in any order.

Answer

The part must first make contact with the simulator for datum C, then B, then A.

Answer

The part should be oriented to make optimal contact with all datum simulators simultaneously.

Question 5

In a scenario where a cylindrical hole is designated as a primary datum feature, what does the resulting datum represent?

Accepted Answer

The theoretically exact axis of the datum feature simulator that contacts the high points of the hole.

Answer

The surface of the hole

Answer

The axis of the smallest inscribed cylinder

Answer

The axis of the largest circumscribed cylinder

Question 6

What is the primary purpose of establishing a Datum Reference Frame (DRF) in GD&T?

Accepted Answer

To create a common, stable coordinate system for dimensioning, tolerancing, and inspection.

Answer

To make the drawing look more professional and complete.

Answer

To provide a system for applying material condition modifiers.

Answer

To specify the manufacturing processes to be used.