GD&T Fundamentals Based on ASME
Y14.5 2025 questions n answers
ASME Y14.5-2025 - ANS ✔This standard establishes symbols, rules, definitions, requirements,
defaults, and recommended practices for station and interpreting dimensioning, tolerancing,
and related requirements for use on engineering drawings, models defined in digital data files,
and related documents
Engineering Drawing - ANS ✔A document (or digital data file) that communicates a precise
description of a part
Basic Dimension - ANS ✔A theoretically exact dimension. Intolerance dimensions are basic.
Defines theoretical exact location, size, or true profile of a part feature. Defines gage
information, such as datum targets. Geometric tolerances apply to part features defined with
basic dimensions
Bilateral Tolerance - ANS ✔A tolerance in which variation is permitted in both directions from
the specified dimension or true profile
Dimension - ANS ✔A numerical value(s)or mathematical expression in appropriated unites of
measure used to define the shape, size, orientation, or location of a part feature between part
features.
Equal Bilateral Tolerance - ANS ✔A tolerance in which variation is permitted equally in both
directions from the specified dimension or true profile
Flag note - ANS ✔Notes that are located with the general notes, but apply only at specific areas
or points on a drawing.
,General note - ANS ✔A note that applies to the entire drawing. Located in the notes area.
Unambiguous. Grammatically correct. Stated in present tense
Limit Dimensioning - ANS ✔A dimension that has its high and low limits stated
Local note - ANS ✔Notes that are located at the specific area or point of application on a
drawing. Do not included in General and Specified Note section. View titles and scales are not
local notes
Nominal size - ANS ✔The designation used for purposes of general identification.
Plus and Minus Tolerancing - ANS ✔The nominal of a dimension is given first, followed by a plus-
minus expression of a tolerance
Tolerance - ANS ✔The total amount a dimension or feature is permitted to vary. The tolerance is
the difference between the maximum and minimum limits
Unequal Bilateral Tolerance - ANS ✔A tolerance that permits unequal amounts of variation in
both directions from the specified dimension or true profile
Unilateral Tolerance - ANS ✔A tolerance in which variation is permitted in only one direction
from the specified dimension.
Units of Measurement - ANS ✔Decimal inch and Metric SI (Millimeter)
30° - ANS ✔Decimal Degrees
30° 25' 0" - ANS ✔Degrees, minutes, seconds
,Metric Unit Convention - ANS ✔Trailing zeros are always omitted after the last significant digit.
Zero precedes the decimal point for values less than 1
Fundamental Rule (q) - ANS ✔The nominal value does not establish a target for function or
manufacturing. A note is required to establish a functional or manufacturing target
Interpreting Dimensional Limits - ANS ✔All dimensional limits are ABSOLUTE. Including decimal
place. 20.021 is bad if the tolerance is 20.020
Types of Engineering Drawing Notes - ANS ✔General, Flag, and Local
Why CAD models require dimensions and tolerances - ANS ✔The model may be precise, but the
part will have variation from: part factors, operator, machine tool, fixture, tooling, and
measurement
How CAD models communicate dimensions and tolerances - ANS ✔May be on separate
engineering drawing or graphic sheet associated with the model, or as attribute data associated
to the model per ASME Y14.41
Models Without dimensions and tolerances - ANS ✔There is no method to communicate
allowable part variation, make engineering calculations, inspect the part to determine fitness
for use
Directly toleranced dimension - ANS ✔Dimension with an associated plus/minus tolerance or
limit dimension values. NOTE: Where a plus/minus General tolerance is applied to a dimension,
the dimension is considered a directly toleranced dimension. Costly and not being used as
frequently
, Functional Dimensioning - ANS ✔A dimensioning approach that defines a part based on the
product (fit and function) requirements
Geometric Dimensioning and Tolerancing (GD&T) - ANS ✔A symbolic language used on
engineering drawings and annotated models to communicate allowable variation of part
geometry. Referred to as functional dimensioning
The Directly Toleranced Dimensioning Method Is UNSAFE - ANS ✔Undefined measurement
setup. No indication of measurement origin. Square or rectangular tolerances zones.
Accumulation of tolerances. Fixed-size tolerance zones. Exact start point of dimension
undefined
Potential consequences of the Directly Toleranced Dimensioning Method - ANS ✔Have several
Interpretations: increased manufacturing costs, part acceptance disputes, assembly problems
Three legitimate uses for the directly toleranced dimensioning method - ANS ✔if a dimension
cannot be measured with a caliper, radius gage, protractor or similar instrument, a geometric
tolerance with datum references must be specified
Where GD&T should be used - ANS ✔Reduce manufacturing costs, protect an important
functional relationship on a part, ensure that the part can be assembled, reduce drawing
revisions, verify the part with a functional gage, improved measurement repeatability,
outsource the part, analyze the design
Four major benefits of using GD&T - ANS ✔Improves communication, provides better product
design, increases tolerances for production, and lower costs
Improves communication - ANS ✔Uniformity in drawing specifications and interpretation
improves communication
Provides better product design - ANS ✔Functional dimensioning provides better designs
Y14.5 2025 questions n answers
ASME Y14.5-2025 - ANS ✔This standard establishes symbols, rules, definitions, requirements,
defaults, and recommended practices for station and interpreting dimensioning, tolerancing,
and related requirements for use on engineering drawings, models defined in digital data files,
and related documents
Engineering Drawing - ANS ✔A document (or digital data file) that communicates a precise
description of a part
Basic Dimension - ANS ✔A theoretically exact dimension. Intolerance dimensions are basic.
Defines theoretical exact location, size, or true profile of a part feature. Defines gage
information, such as datum targets. Geometric tolerances apply to part features defined with
basic dimensions
Bilateral Tolerance - ANS ✔A tolerance in which variation is permitted in both directions from
the specified dimension or true profile
Dimension - ANS ✔A numerical value(s)or mathematical expression in appropriated unites of
measure used to define the shape, size, orientation, or location of a part feature between part
features.
Equal Bilateral Tolerance - ANS ✔A tolerance in which variation is permitted equally in both
directions from the specified dimension or true profile
Flag note - ANS ✔Notes that are located with the general notes, but apply only at specific areas
or points on a drawing.
,General note - ANS ✔A note that applies to the entire drawing. Located in the notes area.
Unambiguous. Grammatically correct. Stated in present tense
Limit Dimensioning - ANS ✔A dimension that has its high and low limits stated
Local note - ANS ✔Notes that are located at the specific area or point of application on a
drawing. Do not included in General and Specified Note section. View titles and scales are not
local notes
Nominal size - ANS ✔The designation used for purposes of general identification.
Plus and Minus Tolerancing - ANS ✔The nominal of a dimension is given first, followed by a plus-
minus expression of a tolerance
Tolerance - ANS ✔The total amount a dimension or feature is permitted to vary. The tolerance is
the difference between the maximum and minimum limits
Unequal Bilateral Tolerance - ANS ✔A tolerance that permits unequal amounts of variation in
both directions from the specified dimension or true profile
Unilateral Tolerance - ANS ✔A tolerance in which variation is permitted in only one direction
from the specified dimension.
Units of Measurement - ANS ✔Decimal inch and Metric SI (Millimeter)
30° - ANS ✔Decimal Degrees
30° 25' 0" - ANS ✔Degrees, minutes, seconds
,Metric Unit Convention - ANS ✔Trailing zeros are always omitted after the last significant digit.
Zero precedes the decimal point for values less than 1
Fundamental Rule (q) - ANS ✔The nominal value does not establish a target for function or
manufacturing. A note is required to establish a functional or manufacturing target
Interpreting Dimensional Limits - ANS ✔All dimensional limits are ABSOLUTE. Including decimal
place. 20.021 is bad if the tolerance is 20.020
Types of Engineering Drawing Notes - ANS ✔General, Flag, and Local
Why CAD models require dimensions and tolerances - ANS ✔The model may be precise, but the
part will have variation from: part factors, operator, machine tool, fixture, tooling, and
measurement
How CAD models communicate dimensions and tolerances - ANS ✔May be on separate
engineering drawing or graphic sheet associated with the model, or as attribute data associated
to the model per ASME Y14.41
Models Without dimensions and tolerances - ANS ✔There is no method to communicate
allowable part variation, make engineering calculations, inspect the part to determine fitness
for use
Directly toleranced dimension - ANS ✔Dimension with an associated plus/minus tolerance or
limit dimension values. NOTE: Where a plus/minus General tolerance is applied to a dimension,
the dimension is considered a directly toleranced dimension. Costly and not being used as
frequently
, Functional Dimensioning - ANS ✔A dimensioning approach that defines a part based on the
product (fit and function) requirements
Geometric Dimensioning and Tolerancing (GD&T) - ANS ✔A symbolic language used on
engineering drawings and annotated models to communicate allowable variation of part
geometry. Referred to as functional dimensioning
The Directly Toleranced Dimensioning Method Is UNSAFE - ANS ✔Undefined measurement
setup. No indication of measurement origin. Square or rectangular tolerances zones.
Accumulation of tolerances. Fixed-size tolerance zones. Exact start point of dimension
undefined
Potential consequences of the Directly Toleranced Dimensioning Method - ANS ✔Have several
Interpretations: increased manufacturing costs, part acceptance disputes, assembly problems
Three legitimate uses for the directly toleranced dimensioning method - ANS ✔if a dimension
cannot be measured with a caliper, radius gage, protractor or similar instrument, a geometric
tolerance with datum references must be specified
Where GD&T should be used - ANS ✔Reduce manufacturing costs, protect an important
functional relationship on a part, ensure that the part can be assembled, reduce drawing
revisions, verify the part with a functional gage, improved measurement repeatability,
outsource the part, analyze the design
Four major benefits of using GD&T - ANS ✔Improves communication, provides better product
design, increases tolerances for production, and lower costs
Improves communication - ANS ✔Uniformity in drawing specifications and interpretation
improves communication
Provides better product design - ANS ✔Functional dimensioning provides better designs
