Question 1

When checking the accuracy of a flat surface against a datum surface, there will theoretically be more than three points on the flat surface touching the datum surface (gage).

Accepted Answer

In theory, when checking the accuracy of a flat surface against a datum surface, only three points on the flat surface will be in perfect contact with the datum surface. This is because three points define a plane, and any additional points would not necessarily touch unless the surfaces are perfectly flat and parallel.

Question 2

When only a part of a surface is to be designated as a datum, a ____ line drawn parallel to the surface is used to indicate the portion of the surface acting as the datum.&#10;A) center&#10;B) chain&#10;C) visible&#10;D) cutting-plane

Accepted Answer

A chain line, characterized by a series of dashes and two dots, is used to indicate a specific portion of a surface that serves as a datum when only a part of the surface is to be designated as such. This helps in specifying the exact area of interest on technical drawings.

Question 3

The three types of datums are primary, secondary, and ____________________.

Accepted Answer

tertiary

Question 4

Another name for a three-plane datum system is __________________________________________________.

Accepted Answer

The answer of Another name for a three-plane datum system...

Question 5

If a part is brought into contact with a secondary plane while lying on a primary plane, it will theoretically touch a minimum of ____ points.&#10;A) two&#10;B) three&#10;C) one&#10;D) four or more

Accepted Answer

When a part is brought into contact with a secondary plane while lying on a primary plane, it will touch a minimum of two points. This is because two points define a line and the part will rest on this line of contact between the two planes.

Question 6

When a chain line is used to designate a datum, its length must be dimensioned.

Accepted Answer

When using a chain line to designate a datum in a drawing or a plan, it is necessary to provide its length as a dimension to establish it clearly as a reference point for the other elements in the layout. Without this information, users may have difficulty locating the chain line accurately and interpreting its significance.

Question 7

A datum feature is a feature of a part which is used to establish the location of a datum.

Accepted Answer

A datum feature is indeed used to establish the location of a datum. The datum feature is used as a reference point for measuring other features on the part.

Question 8

A surface plate can be used as a primary datum for a part with a flat surface.

Accepted Answer

A surface plate is a flat, level table for placing parts on and checking their flatness and parallelism. It can be used as a primary datum for a part with a flat surface that needs to be measured or inspected for accuracy.

Question 9

Geometric tolerances, such as straightness and flatness, refer to unrelated lines and surfaces and generally relate to datums.

Accepted Answer

Geometric tolerances like straightness and flatness are form tolerances and do not relate to datums, as they apply to individual features without reference to other features.

Question 10

When a part is touching primary and secondary datum planes and comes in contact with a tertiary plane, it theoretically touches the tertiary plane in ____.&#10;A) four or more points&#10;B) three points&#10;C) two points&#10;D) one point

Accepted Answer

When a part is touching primary and secondary datum planes and then comes in contact with a tertiary plane, it theoretically touches the tertiary plane at one point. This is because the primary datum establishes a plane, the secondary datum establishes a line (requiring two points of contact), and the tertiary datum establishes a single point of contact, ensuring full spatial constraint without over-constraining the part.

Question 11

A point, axis, or plane from which dimensions are measured, or to which geometric tolerances are referenced, is a ____________________

Accepted Answer

The answer of A point, axis, or plane from which...

Question 12

Datums are exact geometric points, axes, or ____________________, each based on one or more datum features of the part.

Accepted Answer

The answer of Datums are exact geometric points, axes, or...

Question 13

The datum feature symbol is ____.&#10;A)  &#10;B)  &#10;C)  &#10;D)

Accepted Answer

The answer of The datum feature symbol is ____.&#10;A) ...

Deck 40: The Datum Reference Frame