Gary K. Griffith
Geometric Dimensioning
and Tolerancing
ASME Y14.5M -1994
10th Edition
Metric Examples
Function & Relationships z function z
function
Benefits z
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z
z
z
z
Typical Problems
z Coordinate dimensioning of functional features z Incorrect or wrong datums
z Guessing at tolerances
z Dimensioning from centerlines
z Ambiguous notes
z Not performing stackup analyses
z Not considering the assembly
z Many more……
General Symbols
Counterbore, Countersink, & Depth symbols are not yet recognized by the ISO standard.
Countersink Symbol
Spherical Radius Symbol
Spherical
Diameter
Symbol
Dimension
Origin Symbol
General Symbols
Radius Symbol (precedes all
radii on the drawing)
Symbol for a Reference Dimension
Controlled Radius Symbol (New)
General Symbols
Dimension Not to Scale
Symbol for “X”number of places
General Symbols
All Around Symbol
Symbol for square area or feature
General Symbols
Dimension has been
toleranced based on
statistical approach
Functional Symbol Families
Feature Control Frame
FEATURE CONTROL FRAMES
POSITION WITHIN A 0.5 CYLINDRICAL
TOLERANCE ZONE (RFS UNDERSTOOD)
WITH RESPECT TO PRIMARY DATUM A
AND SECONDARY DATUM C.
POSITION WITHIN A 0.25 CYLINDRICAL
TOLERANCE ZONE AT MMC WITH
RESPECT TO PRIMARY DATUM A,
SECONDARY DATUM C, AND TERTIARY
DATUM B
CIRCULAR RUNOUT WITHIN 0.13 (F.I.M.)
UNDERSTOOD) FROM PRIMARY
MULTIPLE DATUM A-B
PARALLEL TO PRIMARY MULTIPLE
DATUM C-D WITHIN TWO PARALLEL
PLANES 0.25 APART
General Rule #1
Size features must have perfect form at MMC size
Size tolerances control
form as well as size
Rule 1 does not apply to a. Free state parts b. Standard stock
Rule #2 and #3 z
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Virtual condition is the basis for mating part design
Virtual Condition / Virtual Size z
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