GD&T Datum Systems & Reference Frames 3

Question 1

Datum targets are used primarily when:

Accepted Answer

The datum feature surface is irregular, large, or warped

Answer

Datum targets (points, lines, or areas) are used when full-surface contact is impractical due to surface irregularities, large surfaces, or casting/forging conditions.

Question 2

A datum target point is represented on a drawing by:

Accepted Answer

A circle divided horizontally with an X

Answer

A datum target point is shown as a circle divided by a horizontal line, with an X in the lower half and the datum target identification in the upper half.

Question 3

What does it mean when a datum reference is labeled with [CF] (Continuous Feature)?

Accepted Answer

Two or more interrupted features are treated as one datum feature

Answer

The [CF] modifier indicates that two or more separated (interrupted) features are treated as a single, continuous datum feature for establishing the datum.

Question 4

In a datum reference frame, the tertiary datum plane is established by a minimum of how many points of contact?

Accepted Answer

One

Answer

The tertiary datum plane requires a minimum of one point of contact because it only needs to constrain one remaining translational degree of freedom.

Question 5

Which statement best describes a 'customized datum reference frame'?

Accepted Answer

A DRF where specific degrees of freedom are selectively constrained by each datum

Answer

A customized DRF (per ASME Y14.5-2018) allows specific translational and rotational degrees of freedom to be selectively assigned to each datum reference using bracketed letter codes.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test

GD&T Datum Systems & Reference Frames 3