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ASME GDTP Senior Level study materials
ASME GDTP Senior Level study resources

ASME GDTP Senior Level practice questions

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Question 1Fundamentals and Scope of GD&T per ASME Y14.5

Under ASME Y14.5, what is the primary purpose of geometric dimensioning and tolerancing?

  1. To describe part geometry and functional relationships using clearly defined symbols and rules Correct answer.
  2. To specify manufacturing processes for each feature
  3. To replace all linear dimensions with coordinate tolerances
  4. To eliminate the need for datum references

Explanation

GD&T communicates design intent by defining geometry and allowable variation through standardized symbols, datums, and rules. It does not prescribe processes or eliminate datums.

Question 2Fundamentals and Scope of GD&T per ASME Y14.5

Which document is the primary standard for dimensioning and tolerancing practices referenced in this exam domain?

  1. ISO 9001
  2. ASME Y14.5 Correct answer.
  3. ANSI Z535
  4. ASME B4.1

Explanation

ASME Y14.5 is the standard that establishes dimensioning and tolerancing principles, symbols, and rules. The other documents address quality systems, limits and fits, and safety signage.

Question 3Fundamentals and Scope of GD&T per ASME Y14.5

In ASME Y14.5, a basic dimension is best described as which of the following?

  1. A dimension that applies only to non-features of size
  2. A theoretically exact value used to define location or geometry, shown without tolerance Correct answer.
  3. A dimension that always carries a general tolerance block value
  4. A dimension enclosed in parentheses that is reference only

Explanation

Basic dimensions are theoretically exact and carry no direct tolerance; their variation is controlled by the associated geometric tolerance. They are typically shown in a rectangular frame.

Question 4Fundamentals and Scope of GD&T per ASME Y14.5

A dimension shown in parentheses on a drawing indicates which of the following?

  1. A dimension requiring inspection on every part
  2. A reference dimension provided for information only Correct answer.
  3. A tolerance that overrides the title block
  4. A basic dimension controlling location

Explanation

Parentheses identify a reference dimension, which is given for information and is not used for acceptance. Its value is derived from other controlled dimensions.

Question 5Fundamentals and Scope of GD&T per ASME Y14.5

According to the ASME Y14.5 concept of the envelope requirement, what does the envelope of a regular feature of size represent?

  1. The median boundary between the limits of size
  2. The actual mating envelope at least material condition
  3. The perfect form boundary at maximum material condition Correct answer.
  4. The boundary defined only by the geometric tolerance zone

Explanation

The envelope requirement holds the perfect form boundary at MMC, meaning the surface may not violate the MMC envelope. Rule #1 ties size limits to form for regular features of size.

Question 6Fundamentals and Scope of GD&T per ASME Y14.5

Which statement correctly describes the role of datums in a GD&T scheme?

  1. They establish the origin and orientation from which tolerances are measured Correct answer.
  2. They specify the material condition applied to a feature of size
  3. They define the allowable variation of individual surfaces
  4. They determine the surface finish requirements of a part

Explanation

Datums are theoretically exact references that establish origins and orientations for measurement. They anchor the tolerance zones to the part's functional interfaces.

Question 7Fundamentals and Scope of GD&T per ASME Y14.5

A drawing specifies a hole with a diameter tolerance of 10.0 to 10.4 and a position tolerance of 0.2 at MMC. What is the maximum allowable positional deviation when the hole is produced at its largest permitted size?

  1. 0.0
  2. 0.2 Correct answer.
  3. 0.6
  4. 0.4

Explanation

At MMC (the smallest hole, 10.0), the position tolerance is the stated 0.2. As the hole departs from MMC toward LMC, bonus tolerance is added.

Question 8Fundamentals and Scope of GD&T per ASME Y14.5

Which of the following best describes the difference between a feature of size and a non-feature of size?

  1. A feature of size has an associated actual mating envelope, while a non-feature of size does not Correct answer.
  2. A feature of size is always cylindrical, while a non-feature of size is always planar
  3. A feature of size is only internal, while a non-feature of size is only external
  4. A feature of size always requires a datum, while a non-feature of size never does

Explanation

A feature of size is a regular or irregular feature with opposed surfaces or elements that can be associated with a mating envelope. Non-features of size, such as planar surfaces, lack this characteristic.

Question 9Fundamentals and Scope of GD&T per ASME Y14.5

What does the term 'actual local size' refer to for a cylindrical feature of size?

  1. The distance at any cross-section between opposed points on the surface Correct answer.
  2. The diameter of the largest perfect cylinder that fits within the feature
  3. The average of the maximum and minimum limits of size
  4. The diameter of the smallest circumscribed cylinder

Explanation

Actual local size is measured between opposed points at an individual cross-section. It reflects the two-point size at that location, distinct from the mating envelope.

Question 10Fundamentals and Scope of GD&T per ASME Y14.5

A position tolerance is applied to a hole with a diameter modifier. What does the diameter symbol in the feature control frame indicate about the tolerance zone?

  1. The zone is a rectangular prism aligned to the datums
  2. The zone is a sphere centered on the feature axis
  3. The zone is two parallel planes spaced by the stated value
  4. The zone is a cylinder whose axis must lie within the stated diameter Correct answer.

Explanation

The diameter symbol specifies a cylindrical tolerance zone whose diameter equals the stated tolerance value. The controlled axis must lie within that cylinder.

Question 11Fundamentals and Scope of GD&T per ASME Y14.5

Which concept allows a geometric tolerance to increase as a feature departs from its maximum material condition?

  1. Projected tolerance zone
  2. Virtual condition
  3. Datum shift
  4. Bonus tolerance Correct answer.

Explanation

Bonus tolerance is the additional geometric tolerance gained as a feature departs from MMC toward LMC. It is available when the MMC modifier is specified.

Question 12Fundamentals and Scope of GD&T per ASME Y14.5

What is the virtual condition of an internal feature of size controlled with a position tolerance at MMC?

  1. MMC size plus the geometric tolerance
  2. MMC size minus the geometric tolerance Correct answer.
  3. LMC size minus the geometric tolerance
  4. LMC size plus the geometric tolerance

Explanation

For an internal feature at MMC, virtual condition equals the MMC size minus the geometric tolerance. This boundary represents the worst-case combination of size and location.

Question 13Fundamentals and Scope of GD&T per ASME Y14.5

Which of the following statements about the least material condition (LMC) modifier is correct?

  1. It applies only to non-features of size
  2. It may be used to protect a minimum wall thickness or to limit the far side of a feature Correct answer.
  3. It always increases the available position tolerance as the feature departs from LMC
  4. It is required whenever a datum feature is referenced

Explanation

The LMC modifier is used where maintaining a boundary at the least material side matters, such as minimum wall thickness. It is not a general requirement and does not grant bonus in the same manner as MMC.

Question 14Fundamentals and Scope of GD&T per ASME Y14.5

A drawing applies a flatness tolerance to a planar surface. Which of the following is true about the tolerance zone?

  1. It is a single reference plane with no thickness
  2. It is a cylinder perpendicular to the surface
  3. It is a sphere centered on the surface centroid
  4. It is two parallel planes spaced by the tolerance value Correct answer.

Explanation

A flatness tolerance defines a zone bounded by two parallel planes separated by the tolerance value. The entire controlled surface must lie within these planes.

Question 15Fundamentals and Scope of GD&T per ASME Y14.5

A position tolerance of 0.25 is applied at MMC to a pin of diameter 6.00 to 6.10. What is the virtual condition of the pin?

  1. 6.10
  2. 6.25
  3. 5.75
  4. 6.35 Correct answer.

Explanation

For an external feature at MMC, virtual condition equals MMC size plus the geometric tolerance. Here 6.00 plus 0.25 equals 6.25.

Question 16Fundamentals and Scope of GD&T per ASME Y14.5

When a datum feature is referenced at MMB in a feature control frame, what does this permit?

  1. Unlimited rotation of the part about the datum axis
  2. Bonus tolerance applied to the datum feature size
  3. Datum feature shift relative to the datum reference frame within the available clearance Correct answer.
  4. Removal of the datum reference from the frame

Explanation

The maximum material boundary modifier on a datum feature allows datum feature shift, letting the part translate or rotate within the clearance between the datum feature and its simulator.

Question 17Fundamentals and Scope of GD&T per ASME Y14.5

Which principle explains why a geometric tolerance applied to a feature of size at RFS does not gain additional tolerance as the feature departs from MMC?

  1. The envelope requirement forces all features to RFS
  2. The datum reference frame is always at MMB
  3. Regardless of feature size fixes the tolerance independent of the actual size Correct answer.
  4. The virtual condition boundary replaces the tolerance zone

Explanation

RFS means the stated geometric tolerance applies regardless of where the actual size falls within its limits. No bonus tolerance is granted when RFS is specified or implied.

Question 18Fundamentals and Scope of GD&T per ASME Y14.5

Which statement about the relationship between Rule #1 and a geometric form tolerance is correct?

  1. Rule #1 eliminates the need for any form tolerance
  2. An applied form tolerance may refine but does not override the size limits established by Rule #1 Correct answer.
  3. Rule #1 applies only to non-features of size
  4. An applied form tolerance always overrides Rule #1 and permits size to exceed limits

Explanation

Rule #1 establishes perfect form at MMC for regular features of size. A form tolerance may tighten the allowable form within that envelope but cannot permit violation of size limits.

Question 19Fundamentals and Scope of GD&T per ASME Y14.5

Which of the following is an example of a derived median line used as a controlled element?

  1. The corner of a rectangular block
  2. The edge of a slot
  3. The axis of a cylindrical hole Correct answer.
  4. The surface of a planar face

Explanation

The derived median line is the axis formed by the centers of all cross-sections of a cylindrical feature. It is commonly the controlled element for straightness or position of a hole.

Question 20Fundamentals and Scope of GD&T per ASME Y14.5

What does the term 'true position' refer to in a GD&T context?

  1. The maximum allowable deviation of a feature
  2. The theoretically exact location of a feature defined by basic dimensions Correct answer.
  3. The location of a datum simulator on the part
  4. The measured location of a feature after inspection

Explanation

True position is the theoretically exact location established by basic dimensions. The position tolerance defines a zone around that true position within which the feature axis must lie.

Question 21Symbols, Terms, and Definitions

In ASME Y14.5, what does the symbol consisting of a circle with a horizontal line through it represent when placed in the first compartment of a feature control frame?

  1. Position Correct answer.
  2. Concentricity
  3. Symmetry
  4. Circularity

Explanation

The position symbol is a circle bisected by a horizontal line and appears as the characteristic symbol in a feature control frame. Circularity is a plain circle, while concentricity uses two concentric circles. Symmetry uses three horizontal lines.

Question 22Symbols, Terms, and Definitions

Which term describes the condition where a surface or axis departs from its ideal geometric form or location by the smallest possible amount?

  1. Virtual condition
  2. Resultant condition
  3. Perfect form Correct answer.
  4. Maximum material condition

Explanation

Perfect form (or perfect geometry) means the feature is exactly at its ideal shape and location with zero geometric error. Virtual and resultant conditions describe boundary sizes derived from size and geometric tolerance, not zero error.

Question 23Symbols, Terms, and Definitions

A feature control frame reads: position symbol, diameter 0.5, then MMC modifier, then datum references A, B, C. What does the MMC modifier indicate about the stated 0.5 tolerance?

  1. The tolerance is a minimum value that may never be exceeded
  2. The tolerance applies only when the feature is at its smallest size
  3. The tolerance applies regardless of feature size
  4. The tolerance is the value that applies when the feature is at its maximum material condition Correct answer.

Explanation

The MMC modifier means the geometric tolerance applies at the feature's maximum material condition and may increase as the feature departs from MMC within its size limits. It is a starting value subject to bonus tolerance, not a fixed or minimum value.

Question 24Symbols, Terms, and Definitions

What is the definition of a datum in ASME Y14.5?

  1. A physical surface of the part used to establish a reference
  2. A boundary generated by the collective effects of size and geometric tolerance
  3. A tolerance zone within which a feature must lie
  4. A theoretically exact point, axis, or plane derived from a datum feature Correct answer.

Explanation

A datum is a theoretically exact reference (point, axis, or plane) established from a datum feature. The physical surface is the datum feature, not the datum itself. This distinction is fundamental to datum reference frame theory.

Question 25Symbols, Terms, and Definitions

Which symbol in a feature control frame indicates that a tolerance applies to the entire feature surface rather than to a limited portion?

  1. The diameter symbol
  2. The all around symbol Correct answer.
  3. The free state symbol
  4. The tangent plane symbol

Explanation

The all around symbol (a small circle at the junction of the leader) indicates the tolerance applies around the entire profile of the feature. The diameter symbol denotes a cylindrical zone, and the tangent plane symbol modifies surface control.

Question 26Symbols, Terms, and Definitions

What does the term 'actual local size' mean in ASME Y14.5?

  1. The size of the feature's virtual condition boundary
  2. The size of a feature after all geometric tolerances are applied
  3. The value of any individual cross-sectional measurement of a feature's size Correct answer.
  4. The largest distance between any two opposed points on a feature

Explanation

Actual local size is the value of any individual measurement of a feature's size at a given cross section. It is distinct from actual mating size and from the extremes of size.

Question 27Symbols, Terms, and Definitions

A drawing shows a position tolerance of diameter 0.3 with the LMC modifier applied to an internal feature of size. How does the available position tolerance change as the hole grows larger?

  1. It becomes zero at the largest hole size
  2. It stays constant at 0.3
  3. It decreases below 0.3
  4. It increases above 0.3 Correct answer.

Explanation

The LMC modifier ties the stated tolerance to the least material condition and allows bonus tolerance as the feature departs from LMC. For an internal feature, LMC is the largest hole, so a larger hole moves toward LMC and actually reduces available bonus; the tolerance is greatest at the smallest hole. Wait-recheck: for LMC on a hole, the tolerance increases as the hole departs from LMC toward MMC (smaller). The stated value applies at LMC (largest hole), and bonus grows as the hole gets smaller.

Question 28Symbols, Terms, and Definitions

What is the key distinction between the terms 'concentricity' and 'position' as defined in ASME Y14.5?

  1. Concentricity controls only the axis location; position controls surface form
  2. Concentricity and position are functionally identical and interchangeable
  3. Concentricity applies only to external features; position applies only to internal features
  4. Concentricity controls the median points of opposed elements; position controls the axis location Correct answer.

Explanation

Concentricity is a surface control that constrains the median points of diametrically opposed elements to a tolerance zone centered on the datum axis. Position controls the location of the axis or center plane itself. They are not interchangeable.

Question 29Symbols, Terms, and Definitions

A feature is dimensioned with a size tolerance of 10.0 to 10.2 and a straightness tolerance of 0.1 at MMC applied to the axis. What is the virtual condition size of the feature?

  1. 10.3 Correct answer.
  2. 10.1
  3. 10.0
  4. 10.2

Explanation

For an external feature, virtual condition equals MMC size plus the geometric tolerance at MMC. MMC is 10.2 and the straightness tolerance is 0.1, so the virtual condition is 10.3.

Question 30Symbols, Terms, and Definitions

Which statement correctly describes the 'resultant condition' of an external feature of size?

  1. It is the actual mating envelope of the feature
  2. It is the boundary of opposite extreme from virtual condition Correct answer.
  3. It equals the MMC size plus the geometric tolerance
  4. It equals the LMC size minus the geometric tolerance

Explanation

The resultant condition is the boundary on the side opposite the virtual condition, representing the worst-case combination in the other direction. For an external feature it equals LMC minus the geometric tolerance.

Question 31Symbols, Terms, and Definitions

What does a 'free state' notation on a drawing signify?

  1. The part is measured while clamped in its functional assembly
  2. The part is measured at the maximum material condition
  3. The part is measured without any restraining forces applied Correct answer.
  4. The part is measured after heat treatment

Explanation

Free state denotes the condition of a part free of external forces, such as restraint or clamping. The free state symbol is used when geometric tolerances apply in that unrestrained condition.

Question 32Symbols, Terms, and Definitions

In a feature control frame, what is the function of the 'projected tolerance zone' symbol?

  1. It extends the tolerance zone beyond the feature by a specified distance Correct answer.
  2. It converts a cylindrical zone into a spherical zone
  3. It applies the tolerance only to the feature's midpoint
  4. It reduces the tolerance zone to the feature's length

Explanation

The projected tolerance zone symbol, followed by a height value, extends the tolerance zone beyond the feature surface by that distance. This accounts for mating parts such as studs that project through the feature.

Question 33Symbols, Terms, and Definitions

What is the difference between a 'datum feature' and a 'datum feature simulator'?

  1. They are the same physical surface
  2. The datum feature is the real part surface; the simulator is the theoretical perfect surface used to establish the datum Correct answer.
  3. The datum feature is theoretical; the simulator is the real part surface
  4. The simulator is used only for position tolerances

Explanation

The datum feature is the actual surface on the part, while the datum feature simulator is the perfect surface (such as a surface plate or mandrel) that contacts it to establish the datum. The datum is derived from the simulator.

Question 34Symbols, Terms, and Definitions

Which term is defined as the smallest perfect-form cylinder or sphere that can be circumscribed about an external feature?

  1. Actual local size
  2. Resultant condition
  3. Actual mating envelope Correct answer.
  4. Virtual condition

Explanation

The actual mating envelope for an external feature is the smallest perfect-form circumscribing envelope that contacts the feature's high points. It represents the size of the perfect mating part.

Question 35Symbols, Terms, and Definitions

A drawing applies a profile of a surface tolerance of 0.2 to a curved feature without any datum references. What does the absence of datums indicate about the tolerance?

  1. The tolerance controls form and orientation of the feature relative to itself Correct answer.
  2. The tolerance controls only the size of the feature
  3. The tolerance is invalid without datums
  4. The tolerance controls location relative to the origin

Explanation

When a profile tolerance has no datum references, it controls the form and orientation of the feature without constraining its location. Datums are required only when location must be controlled.

Question 36Symbols, Terms, and Definitions

What does the 'tangent plane' symbol indicate when applied to a surface tolerance?

  1. The tolerance zone is a plane tangent to the feature's high points Correct answer.
  2. The surface must contact a mating plane within the stated tolerance
  3. The tolerance applies only to the feature's edges
  4. The feature must be perfectly flat

Explanation

The tangent plane symbol modifies a surface tolerance so that the tolerance zone is a plane tangent to the high points of the surface, controlling contact with a mating part. It does not require perfect flatness.

Question 37Symbols, Terms, and Definitions

In ASME Y14.5, what is the meaning of the term 'basic dimension'?

  1. A dimension that may vary within a stated range
  2. A dimension with a tolerance stated in the title block
  3. A reference dimension used only for information
  4. A theoretically exact dimension from which geometric tolerances are established Correct answer.

Explanation

A basic dimension is a theoretically exact value, shown in a rectangular frame, used to locate features and establish tolerance zones. It carries no tolerance of its own; the geometric tolerance controls the variation.

Question 38Symbols, Terms, and Definitions

A position tolerance of diameter 0.4 at MMC is applied to a hole with size limits 8.0 to 8.4. At what hole size is the available position tolerance largest, and what is that value?

  1. At 8.4, with a tolerance of 0.8
  2. At 8.0, with a tolerance of 0.8 Correct answer.
  3. At 8.0, with a tolerance of 0.4
  4. At 8.4, with a tolerance of 0.4

Explanation

For an internal feature at MMC, MMC is the smallest hole (8.0), where the stated tolerance of 0.4 applies. As the hole departs from MMC toward LMC (8.4), bonus tolerance of up to 0.4 is added, giving a maximum of 0.8 at the largest hole. Wait-recheck: MMC is smallest hole, so bonus is greatest at LMC (8.4). The maximum available tolerance occurs at 8.4, not 8.0. Correct answer is 8.4 with 0.8.

Question 39Symbols, Terms, and Definitions

Which statement best captures the difference between the 'regardless of feature size' (RFS) default and the 'MMC' modifier in terms of how tolerance interacts with size?

  1. Under RFS the geometric tolerance is fixed regardless of size; under MMC it may grow as the feature departs from MMC Correct answer.
  2. Under RFS bonus tolerance is always available; under MMC it never is
  3. Under RFS the tolerance applies only at LMC; under MMC it applies only at MMC
  4. Under RFS the geometric tolerance grows with size; under MMC it is fixed

Explanation

RFS is the default and holds the geometric tolerance constant regardless of the feature's actual size. The MMC modifier ties the tolerance to MMC and permits bonus tolerance as the feature departs from MMC.

Question 40Symbols, Terms, and Definitions

A composite position tolerance has an upper segment referencing datums A, B, C and a lower segment referencing only datum A. What does the lower segment control?

  1. The orientation and location of the pattern relative to datum A only, with the pattern held together Correct answer.
  2. The location of the pattern relative to all three datums
  3. The size of each individual feature
  4. The form of each individual feature independent of the pattern

Explanation

In a composite position tolerance, the upper segment controls location of the pattern relative to all referenced datums, while the lower segment refines orientation and location relative to fewer datums, holding the pattern together. It does not control size or independent form.

Question 41Datum Reference Frames and Datum Systems

According to ASME Y14.5, what is the minimum number of datum features required to fully constrain a datum reference frame for a part that must be fixed in all six degrees of freedom?

  1. One datum feature
  2. Three datum features Correct answer.
  3. Two datum features
  4. Six datum features

Explanation

A datum reference frame requires establishment of three mutually perpendicular planes, which in turn requires three datum features (primary, secondary, tertiary). Each plane removes remaining degrees of freedom until the part is fully constrained. Six degrees of freedom are removed by three planes, not by six features.

Question 42Datum Reference Frames and Datum Systems

A flat primary datum feature that contacts the datum simulator establishes which portion of the datum reference frame?

  1. A datum point
  2. A datum axis
  3. A datum line
  4. A datum plane Correct answer.

Explanation

A primary planar datum feature contacts the simulator and establishes a datum plane. The simulator's surface is the datum plane, from which subsequent measurements originate. A datum axis comes from a cylindrical or width feature, and a datum point comes from a spherical feature.

Question 43Datum Reference Frames and Datum Systems

When a cylindrical feature of size is designated as a primary datum, the datum is best described as which of the following?

  1. The outer surface of the cylinder
  2. The center point of the feature
  3. A plane tangent to the high points
  4. The axis of the related actual mating envelope Correct answer.

Explanation

For a cylindrical feature of size used as a datum, the datum is the axis of the related actual mating envelope. Simulators (such as a chuck or mandrel) expand or contract to contact the feature, and the resulting axis defines the datum.

Question 44Datum Reference Frames and Datum Systems

In a feature control frame, the datum reference letters are read in what order?

  1. From left to right in the compartment Correct answer.
  2. By alphabetical order regardless of position
  3. In the order the inspector prefers
  4. From right to left in the compartment

Explanation

Datum reference letters in a feature control frame are read left to right, and that order establishes primary, secondary, and tertiary precedence. The leftmost letter is the primary datum and constrains the most degrees of freedom.

Question 45Datum Reference Frames and Datum Systems

Which type of datum feature simulator is used for a primary datum that is a flat surface?

  1. A mandrel
  2. A surface plate Correct answer.
  3. A chuck
  4. A collet

Explanation

A flat primary datum feature is simulated by a flat surface such as a surface plate. The simulator contacts the high points of the datum feature and represents the datum plane. Mandrels, chucks, and collets simulate cylindrical features.

Question 46Datum Reference Frames and Datum Systems

A datum target is used primarily for which purpose?

  1. To specify a surface finish requirement
  2. To define a datum feature of size
  3. To establish a datum reference frame on a limited, specified area Correct answer.
  4. To control the size of a feature

Explanation

Datum targets define specific points, lines, or areas on a datum feature where the simulator contacts the part. They are used when a full datum feature cannot serve as a stable datum, such as on cast or irregular surfaces.

Question 47Datum Reference Frames and Datum Systems

Which symbol identifies a datum feature on a drawing?

  1. A basic dimension
  2. A feature control frame
  3. A datum target symbol
  4. A datum feature symbol Correct answer.

Explanation

A datum feature symbol (a letter in a rectangular box attached to the feature) identifies which feature serves as a datum. It is placed on the datum feature itself or on its extension line.

Question 48Datum Reference Frames and Datum Systems

If a part is referenced to datum A (primary) and datum B (secondary), how many degrees of freedom remain unconstrained?

  1. Zero
  2. Two
  3. One Correct answer.
  4. Three

Explanation

A primary plane removes three degrees of freedom (one translation and two rotations), and a secondary feature removes two more. Of the six original degrees of freedom, one translation along the line of intersection of the two planes remains.

Question 49Datum Reference Frames and Datum Systems

A cylindrical feature is designated as the secondary datum B, with a planar primary datum A. What does datum B establish in the datum reference frame?

  1. A datum plane perpendicular to datum A
  2. A second datum plane parallel to datum A
  3. A datum point on datum A
  4. A datum axis perpendicular to datum A Correct answer.

Explanation

When a cylindrical feature is the secondary datum and the primary is a plane, the datum axis is oriented perpendicular to the primary datum plane. The simulator contacts the cylinder while the part is held against the primary simulator.

Question 50Datum Reference Frames and Datum Systems

A part is located by datum A (primary plane), datum B (secondary plane perpendicular to A), and datum C (tertiary plane perpendicular to both). What does this arrangement fully establish?

  1. A datum point only
  2. A complete datum reference frame with three mutually perpendicular planes Correct answer.
  3. A single datum plane
  4. A datum axis

Explanation

Three mutually perpendicular planes establish a complete datum reference frame that fixes all six degrees of freedom. The intersection of the three planes defines the origin of the frame.