Download - GD&T Document
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DIMENSIONAL ENGINEERING
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1. Introduction
2. Symbols
3. Terms
4. General Rules
5. Datum's
6. Form Control
7. Orientation controls
8. Location controls
9. Run-out
Course Outline
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Course Objectives
Participants will• Be able to explain the main benefits of
GD&T– Diametrical tolerance zone– MMC– Datum's specified in order of precedence
• Develop a solid foundation of GD&T fundamentals– Symbols– Terms– Rules
• Be able to properly apply frequently used geometric controls
• Should be able to demonstrate the working knowledge of application of positional tolerance.
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Introduction to GD&T
• GD&T is a symbolic language. It is used to specify size, shape, orientation and location. GD&T reflects the actual relationship between the mating parts. Drawings with properly applied geometric tolerance provide the best opportunity for uniform interpretation.
• GD&T is a design tool• GD&T communicates the design intent.• Dimensioning & Tolerance ASME Y14.5
1994, is current authorities document specifying the proper application of GD&T.
• Document as grown from– ASA Y14.5 1957– SAE, Automotive, Aerospace Drawing standards &
MIL-STD-8C 1963.– USASI Y14.5 1966– ANSI Y 14.5 1973– ANSI Y14.5M 1982
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When do we use GD&T
• When drawing interpretation must be
same.
• When features are critical to function
or interchangeability.
• When it is important to eliminate the
scrapping of perfectly good parts.
• When it is important to reduce the
drawing changes.
• When functional gauging is required.
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Cylindrical Tolerance zone Vs.
Rectangular Tolerance zone
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SYMBOLS, TERMS and RULES are the
basics of GD&T. They are the alphabets,
definitions and syntax of this language.
You can’t expect to communicate in a
language if you don’t know its words,
symbols and how those words and
symbols fit together
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SymbolsSymbols are essence of this graphic language. It is important not only to know each symbol, but also to know how to apply these symbols to drawings.
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Datum feature symbols attached to features
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Geometric Characteristic
symbol
Geometric tolerance zone
Geometric tolerance
Modifier
Primary Datum
Primary Datum
Datum Modifier
Tertiary Datum
Feature control Frame
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Feature control Frame attached to features
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GD&T Symbology
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TermsBasic Dimension is a numeric value used to describe the theoretically exact size, or profile, or orientation, or location of a feature or datum target. Basic dimensions are used to define or position tolerance zones. They are dimension without tolerances
Datum is a theoretically exact point, line, or plane derived from true geometric counterpart of a specified datum feature. Datum's are the origin from which the location of features are established.
Datum feature is a actual feature on part that is used to establish a datum.
Datum feature simulator is a real surface of adequacy precise form, such as a surface plate or machine table used to contact datum features to establish simulated datum's.
Feature is a physical portion of a part, such as a surface, pin, hole, tab, or slot.
Feature of sizes are features that have a dimension and a size tolerance. FOS is •Cylindrical surface•Two opposed parallel surfaces•A special Surface•Two opposite line elements
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Maximum Material Condition (MMC) of a feature of size is a maximum amount of material within stated limits of the size; for example maximum shaft diameter or minimum hole diameter.
Regardless of feature (RFS) is a term used to indicate that a specified geometric tolerance or a datum reference applies at each increment of size of feature within its limits of size. Regardless of feature size specifies that no bonus tolerance is allowed.
True position is exact location of feature established by basic dimensions. Tolerance zones are located at true position.
Virtual condition for a tolerance specified at MMC is constant boundary generated by the collective effects of the MMC limit of size of feature and the applicable geometric tolerance.
External Features
VC = MMC + Geo. Tol. at MMC
Internal Features
VC = MMC - Geo. Tol. at MMC
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Datum Plane
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Maximum Material Condition
External Features (Pins)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.600
.580
.540
.520
External Features (Pins)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.600 .600 .000 .020 .020
.580 .600 .020 .020 .040
.540 .600 .060 .020 .080
.520 .600 .080 .020 .100
Internal Features (Holes)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.600
.580
.540
.520
Internal Features (Holes)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.600 .520 .080 .020 .100
.580 .520 .060 .020 .080
.540 .520 .020 .020 .040
.520 .520 .000 .020 .020
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RulesRule#1:
When no geometric tolerance is specified, the dimensional tolerance controls the geometric form as well as the size. No element of the feature shall extend beyond of perfect form. The form tolerance increases as the actual size of the feature departs from MMC towards LMC
Rule#2 (1994 standard):
RFS automatically applies to individual tolerances and to datum feature of sizes. MMC & LMC must be specified where required.
Rule#2 (1982 standard):
When using a position control in a feature control frame, MMC, LMC or RFS must be specified for the geometric tolerances and datum features of size.
Rule#3(1982 standard):
For all other geometric controls, RFS automatically applies.
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Rule#4:
All geometric tolerances specified for screw threads apply to the axis of thread derived from pitch diameter. Exceptions must be specified by a note (such as MAJOR DIA, MINOR DIA or PITCH DIA) at which each applies.
Rule#5:
Where datum feature of size is controlled by geometric tolerance and is specified as secondary or tertiary datum, the datum applies at virtual condition with respect to orientation.
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Rule#1
1. What is the straight tolerance is implied in the
drawing above:_________
2. If the pins is produced at a dia. 1.010, it must be
straight within the tolerance? _______
3. If the pins is produced at a dia. 1.015, it must be
straight within the tolerance? _______
4. If the pins is produced at a dia. 1.020, it must be
straight within the tolerance? _______
5. If the pins is produced at a dia. 1.000, it must be
straight within the tolerance? _______
.010
.020
.005
0
.020
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Rule#5
Virtual condition Calculation
Internal Features
MMC 1.010
Geometric Tolerance -.010
Virtual Condition 1.000
External Features
1.025
+ .010
1.035
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Datum's
Datum's are theoretically perfect points, lines and planes. These points, lines and planes exist within a structure of three mutually perpendicular intersecting planes called a datum reference frame.
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Datum feature selection Datum features are selected to meet design requirements:
They should be:
Functional surfaces
Mating surfaces
Readily accessible
Repeatable
Immobilization of part Datum features of a part are oriented and immobilized in selected order of preference relative to three mutually perpendicular intersecting planes of datum reference frame. To properly position the part on the datum reference frame, the datum's must be specified in the order of preference.
Primary datum, contacts the datum reference with minimum of 3 points of contact not in the straight line.
Secondary datum, feature contacts the datum reference frame with minimum of 2 points of contact
Tertiary datum, contacts the datum reference frame with minimum of 1 point of contact
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Datum feature identification
Datum feature symbols are used to identify physical features of a part. Datum feature symbols shall not be applied to center lines, center planes or axes. Datum's may be designated with any letter of alphabet except I, O or Q.
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Multiple datum features
When more than one feature is used to establish a single datum reference letters are separated by a dash and specified in one compartment of feature control frame.
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A Datum is theoretically exact geometric reference.
Datum Quiz
True or False
Datum exist on the part itself.
Simulated datum's are established by processing or inspection equipment.
Surface plates, V-Blocks, may be used to establish the simulated datum's.
Datum features are theoretically exact surfaces.
In datum reference frame consists of three mutually perpendicular planes
Letters I, O or Q are not used as datum symbols
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A D B
A B C
Establish Datum's
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Datum's Exercise
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Form Controls
Straightness Flatness
Circularity Cylindricity
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Extreme Variations of Form Allowed By Size Tolerance
25.1 25
25 (MMC)
25.1 (LMC)
25.1 (LMC)
25 (MMC)
25.1 (LMC)
MMC Perfect Form Boundary
Internal Feature of Size
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Extreme Variations of Form Allowed By Size Tolerance
25 24.9
25 (MMC) 24.9
(LMC)
24.9 (LMC)
MMC Perfect Form Boundary
25 (MMC)
24.9 (LMC)
External Feature of Size
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25 +/-0.25
0.1 Tolerance
0.5 Tolerance
Straightness is the condition where an element of a surface or an axis is a straight line
Straightness (Flat Surfaces)
0.5 0.1
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Straightness (Flat Surfaces)
24.75 min25.25 max
0.5 Tolerance Zone
0.1 Tolerance Zone
The straightness tolerance is applied in the view where the elements to be controlled are represented by a straight line
In this example each line element of the surface must lie within a tolerance zone defined by two parallel lines separated by the specified tolerance value applied to each view. All points on the surface must lie within the limits of size and the applicable straightness limit.
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Straightness (Surface Elements)
MMC
0.1 Tolerance Zone
0.1
MMC
0.1 Tolerance Zone
MMC
0.1 Tolerance Zone
In this example each longitudinal element of the surface must lie within a tolerance zone defined by two parallel lines separated by the specified tolerance value. The feature must be within the limits of size and the boundary of perfect form at MMC. Any barreling or wasting of the feature must not exceed the size limits of the feature.
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Straightness (RFS)
0.1
Outer Boundary (Max)
MMC
0.1 Diameter Tolerance Zone
Outer Boundary = Actual Feature Size + Straightness Tolerance
In this example the derived median line of the feature’s actual local size must lie within a tolerance zone defined by a cylinder whose diameter is equal to the specified tolerance value regardless of the feature size. Each circular element of the feature must be within the specified limits of size. However, the boundary of perfect form at MMC can be violated up to the maximum outer boundary or virtual condition diameter.
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Straightness (MMC)15 14.85
15.1 Virtual Condition
15 (MMC)
0.1 Diameter Tolerance Zone
15.1 Virtual Condition
14.85 (LMC)
0.25 Diameter Tolerance Zone
Virtual Condition = MMC Feature Size + Straightness Tolerance
In this example the derived median line of the feature’s actual local size must lie within a tolerance zone defined by a cylinder whose diameter is equal to the specified tolerance value at MMC. As each circular element of the feature departs from MMC, the diameter of the tolerance cylinder is allowed to increase by an amount equal to the departure from the local MMC size. Each circular element of the feature must be within the specified limits of size. However, the boundary of perfect form at MMC can be violated up to the virtual condition diameter.
0.1 M
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Flatness
Flatness is the condition of a surface having all elements in one plane. Flatness must fall within the limits of size. The flatness tolerance must be less than the size tolerance.
25 +/-0.25
24.75 min25.25 max
0.1
0.1 Tolerance Zone
0.1 Tolerance Zone
In this example the entire surface must lie within a tolerance zone defined by two parallel planes separated by the specified tolerance value. All points on the surface must lie within the limits of size and the flatness limit.
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Circularity is the condition of a surface where all points of the surface intersected by any plane perpendicular to a common axis are equidistant from that axis. The circularity tolerance must be less than the size tolerance
90
90
0.1
0.1 Wide Tolerance Zone
Circularity (Roundness)
In this example each circular element of the surface must lie within a tolerance zone defined by two concentric circles separated by the specified tolerance value. All points on the surface must lie within the limits of size and the circularity limit.
0.1
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Cylindricity
Cylindricity is the condition of a surface of revolution in which all points are equidistant from a common axis. Cylindricity is a composite control of form which includes circularity (roundness), straightness, and taper of a cylindrical feature.
0.1 Tolerance Zone
MMC
0.1
In this example the entire surface must lie within a tolerance zone defined by two concentric cylinders separated by the specified tolerance value. All points on the surface must lie within the limits of size and the Cylindricity limit.
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Orientation controls
Angularity
Perpendicularity
Parallelism
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Angularity (Feature Surface to Datum Surface)
Angularity is the condition of the planar feature surface at a specified angle (other than 90 degrees) to the datum reference plane, within the specified tolerance zone.
A
20 +/-0.5
30 o
A
19.5 min
0.3 Wide Tolerance
Zone
30 o
A
20.5 max
0.3 Wide Tolerance
Zone
30 o
The tolerance zone in this example is defined by two parallel planes oriented at the specified angle to the datum reference plane.
0.3 A
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Angularity is the condition of the feature axis at a specified angle (other than 90 degrees) to the datum reference plane, within the specified tolerance zone.
A
0.3 A
A
60 o
The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented at the specified angle to the datum reference plane.
0.3 Circular Tolerance Zone
0.3 Circular Tolerance Zone
Angularity (Feature Axis to Datum Surface)
NOTE: Tolerance applies to feature at RFS
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0.3 Circular Tolerance Zone
NOTE: Tolerance applies to feature at RFS
Angularity is the condition of the feature axis at a specified angle (other than 90 degrees) to the datum reference axis, within the specified tolerance zone.
0.3 Circular Tolerance Zone
A
Datum Axis A
Angularity (Feature Axis to Datum Axis)
The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented at the specified angle to the datum reference axis.
NOTE: Feature axis must lie within tolerance zone cylinder
0.3 A
o45
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0.3 A
A
0.3 Wide Tolerance Zone
A A
Perpendicularity is the condition of the planar feature surface at a right angle to the datum reference plane, within the specified tolerance zone.
Perpendicularity (Feature Surface to Datum Surface)
0.3 Wide Tolerance Zone
The tolerance zone in this example is defined by two parallel planes oriented perpendicular to the datum reference plane.
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C
Perpendicularity is the condition of the feature axis at a right angle to the datum reference plane, within the specified tolerance zone.
Perpendicularity (Feature Axis to Datum Surface)
0.3 C
0.3 Circular Tolerance Zone
0.3 Diameter Tolerance Zone
0.3 Circular Tolerance Zone
NOTE: Tolerance applies to feature at RFS
The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented perpendicular to the datum reference plane.
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Perpendicularity (Feature Axis to Datum Axis)
NOTE: Tolerance applies to feature at RFS
The tolerance zone in this example is defined by two parallel planes oriented perpendicular to the datum reference axis.
Perpendicularity is the condition of the feature axis at a right angle to the datum reference axis, within the specified tolerance zone.
0.3 Wide Tolerance Zone
A
Datum Axis A
0.3 A
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0.3 A
A
25 +/-0.5
25.5 max
0.3 Wide Tolerance Zone
A
24.5 min
0.3 Wide Tolerance Zone
A
Parallelism is the condition of the planar feature surface equidistant at all points from the datum reference plane, within the specified tolerance zone.
Parallelism (Feature Surface to Datum Surface)
The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.
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A
0.3 Wide Tolerance Zone
Parallelism (Feature Axis to Datum Surface)
0.3 A
A
NOTE: The specified tolerance does not apply to the orientation of the feature axis in this direction
Parallelism is the condition of the feature axis equidistant along its length from the datum reference plane, within the specified tolerance zone.
The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.
NOTE: Tolerance applies to feature at RFS
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A
B
Parallelism (Feature Axis to Datum Surfaces)
A
B
0.3 Circular Tolerance Zone
0.3 Circular Tolerance Zone
0.3 Circular Tolerance Zone
Parallelism is the condition of the feature axis equidistant along its length from the two datum reference planes, within the specified tolerance zone.
The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented parallel to the datum reference planes.
NOTE: Tolerance applies to feature at RFS
0.3 A B
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Parallelism (Feature Axis to Datum Axis)
Parallelism is the condition of the feature axis equidistant along its length from the datum reference axis, within the specified tolerance zone.
A
0.1 A
0.1 Circular Tolerance Zone
0.1 Circular Tolerance Zone
Datum Axis A
The tolerance zone in this example is defined by a cylinder equal to the length of the feature, oriented parallel to the datum reference axis.
NOTE: Tolerance applies to feature at RFS
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Location Controls
True Position
Concentricity
Symmetry
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Positional Tolerance A review of rules and definitions that apply to
positional tolerance
Maximum Material Condition (MMC) of a feature of size is a maximum amount of material within stated limits of the size; for example maximum shaft diameter or minimum hole diameter.
Least Material Condition (LMC) smallest shaft diameter or largest hole diameter.
Datum feature selection:Functional surfacesMating surfacesReadily accessibleRepeatable
Virtual condition for a tolerance specified at MMC is constant boundary generated by the collective effects of the MMC limit of size of feature and the applicable geometric tolerance.
External Features
VC = MMC + Geo. Tol. at MMC
Internal Features
VC = MMC - Geo. Tol. at MMC
Virtual condition is size of the part that results in worst case fit with mating parts. Mating parts are designed to virtual condition; they must always assemble. Functional gauges are made to the virtual condition of the parts they are designed to inspect.
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Rule#5:
Where datum feature of size is controlled by geometric tolerance and is specified as secondary or tertiary datum, the datum applies at virtual condition with respect to orientation.
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External Features (Pins)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.800
.790
.780
.770
.800 .000 .020 .020
.800 .010 .020 .030
.800 .020 .020 .040
.800 .030 .020 .050
MMC
Internal Features (Holes)
Actual Feature Size
MMCBonus
(Difference)Geometric Tolerance
Total Position
Tolerance
.800
.790
.780
.770
.770 .030 .020 .050
.770 .020 .020 .040
.770 .010 .020 .030
.770 .000 .020 .020
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Zero Positional Tolerance
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.000 A B CM
4 X .750 - .830
Zero Positional Tolerance- Exercise
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Project Tolerance Zone
The application of this concept is recommended where the variations in perpendicularity of threaded or press-fit holes could cause fasteners, such as screws, studs, or pins, to interfere with mating parts.
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Exercise
Specify the positional tolerance of .020” for each threaded hole
Include a project tolerance zone project 1.250 above through hole.
Specify the projected tolerance project .750 above the blind hole
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SEPARATE REQUIREMENT SEPARATE REQUIREMENT
Multiple Patterns of the feature
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What are the tolerances for datum hole D if produced at .525: Location
tolerance ? __________ Orientation tolerance? ______________
Virtual conditions are, Location:_______ Orientation___________
What are the tolerances for the 4X.380 holes if produced at .415
Location:_______ Orientation_______ Virtual Condition__________
For datum hole (D), what datum (s) determine (s)
Orientation:___________ Location:____________
For the .380 hole pattern what datum (s) determine (s)
Orientation:__________ Location: __________Clocking:_________
If the gauge is used to check the .380 hole pattern: Datum D pin should
be at what diameter_________
The gauge pins for the .380 holes should be of dia:________
Location Tolerance
.015 + .010 = .025 .015 + .002 = .017
.500 .508
.040 .040 .375
A B & C
A D B
.510 - .002 = .508
.375
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This provides a composite application of positional tolerance for the location of feature patterns as well as the interrelation (position and orientation) of features within these patterns.
Composite Positional Tolerance
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Location (Concentricity)Datum Features at RFS
A
15.9515.90
As Shown on Drawing
Derived Median Points of Diametrically Opposed Elements
Axis of DatumFeature A
Means This:
Within the limits of size and regardless of feature size, all median points of diametrically opposed elements must lie within a 0.5 cylindrical tolerance zone. The axis of the tolerance zone coincides with the axis of datum feature A. Concentricity can only be applied on an RFS basis.
0.5 A6.35 +/- 0.05
0.5 Coaxial Tolerance Zone
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Location (Symmetry)Datum Features at RFS
A
15.9515.90
0.5 A6.35 +/- 0.05
Derived MedianPoints
Center Plane of Datum Feature A
0.5 Wide Tolerance Zone
Means This:
Within the limits of size and regardless of feature size, all median points of opposed elements must lie between two parallel planes equally disposed about datum plane A, 0.5 apart. Symmetry can only be applied on an RFS basis.
As Shown on Drawing
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Runout
Circular Run out
Total Run out
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Datum feature
Datum axis (established from datum feature
Angled surfaces constructed around a datum axis
External surfaces constructed around a datum axis
Internal surfaces constructed around a datum axis
Surfaces constructed perpendicular to a datum axis
Features Applicable to Run out Tolerance
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0+ -
Full Indicator Movement
Maximum Minimum
Total Tolerance
Maximum Reading
Minimum Reading
Full Part Rotation
Measuring position #1 (circular element #1)
Circular Run out
When measuring circular run out, the indicator must be reset to zero at each measuring position along the feature surface. Each individual circular element of the surface is independently allowed the full specified tolerance. In this example, circular run out can be used to detect 2-dimensional wobble (orientation) and waviness (form), but not 3-dimensional characteristics such as surface profile (overall form) or surface wobble (overall orientation).
Measuring position #2 (circular element #2)
Circular run out can only be applied on an RFS basis and cannot be modified to MMC or LMC.
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o360 Part Rotation
50 +/- 2o o
As Shownon Drawing
Means This:
Datum axis A
Single circular element
Circular Run out (Angled Surface to Datum Axis)
0.75 A
A
50 +/-0.25
0+-
NOTE: Circular run out in this example only controls the 2-dimensional circular elements (circularity and coaxially) of the angled feature surface not the entire angled feature surface
Full Indicator Movement( )
The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.
Allowable indicator reading = 0.75 max.
When measuring circular runout, the indicator must be reset when repositioned along the feature surface.
Collect or Chuck
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As Shownon Drawing
50 +/-0.25
0.75 A
Circular Run out (Surface Perpendicular to Datum Axis)
o360 Part Rotation
0+-
Datum axis A
Single circular element
NOTE: Circular run out in this example will only control variation in the 2-dimensional circular elements of the planar surface (wobble and waviness) not the entire feature surface
The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.
Means This:
Allowable indicator reading = 0.75 max.
When measuring circular run out, the indicator must be reset when repositioned along the feature surface.
A
69
0+ -
Allowable indicator reading = 0.75 max.
Single circular element
o360 Part Rotation
Means This:
As Shownon Drawing
50 +/-0.25
0.75 A
Datum axis A
When measuring circular run out, the indicator must be reset when repositioned along the feature surface.
Circular Run out (Surface Coaxial to Datum Axis)
The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.
NOTE: Circular run out in this example will only control variation in the 2-dimensional circular elements of the surface (circularity and coaxially) not the entire feature surface
A
70
0+ -
Allowable indicator reading = 0.75 max.
Single circular element
o360 Part Rotation
Means This:
As Shownon Drawing
0.75 A-B
Datum axis A-B
When measuring circular run out, the indicator must be reset when repositioned along the feature surface.
Circular Run out (Surface Coaxial to Datum Axis)
The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.
NOTE: Circular run out in this example will only control variation in the 2-dimensional circular elements of the surface (circularity and coaxially) not the entire feature surface
Machine center
Machine center
BA
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As Shownon Drawing
50 +/-0.25
Circular Run out (Surface Related to Datum Surface and Axis)
o360 Part Rotation
0+ -
Datum axis B
Single circular element
The tolerance zone for any individual circular element is equal to the total allowable movement of a dial indicator fixed in a position normal to the true geometric shape of the feature surface when the part is located against the datum surface and rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface.
Means This:
A
Allowable indicator reading = 0.75 max.
When measuring circular run out, the indicator must be reset when repositioned along the feature surface.
Collets or Chuck
Stop collar
0.75 A B
Datum plane A
B
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0+
Full Indicator Movement
Total Tolerance
Maximum Reading
Minimum Reading
Full Part Rotation
-
0+ -
Total Run out
Maximum Minimum
When measuring total run out, the indicator is moved in a straight line along the feature surface while the part is rotated about the datum axis. It is also acceptable to measure total run out by evaluating an appropriate number of individual circular elements along the surface while the part is rotated about the datum axis. Because the tolerance value is applied to the entire surface, the indicator must not be reset to zero when moved to each measuring position. In this example, total run out can be used to measure surface profile (overall form) and surface wobble (overall orientation).
Indicator Path
Total run out can only be applied on an RFS basis and cannot be modified to MMC or LMC.
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Full Part Rotation
50 +/- 2o o
As Shownon Drawing
A
50 +/-0.25
0.75 A
Means This:
Datum axis A
0+-
The tolerance zone for the entire angled surface is equal to the total allowable movement of a dial indicator positioned normal to the true geometric shape of the feature surface when the part is rotated about the datum axis and the indicator is moved along the entire length of the feature surface.0
+-
NOTE: Unlike circular run out, the use of total run out will provide 3-dimensional composite control of the cumulative variations of circularity, coaxially, angularity, taper and profile of the angled surface
Total Run out (Angled Surface to Datum Axis)
Collets or Chuck
When measuring total run out, the indicator must not be reset when repositioned along the feature surface.
(applies to the entire feature surface)Allowable indicator reading = 0.75 max.
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0+-
Total Run out (Surface Perpendicular to Datum Axis)
As Shownon Drawing
A
50 +/-0.25
0.75 A
35
10
0+-
Datum axis AFull Part Rotation
35
10
Means This:
NOTE: The use of total run out in this example will provide composite control of the cumulative variations of perpendicularity (wobble) and flatness (concavity or convexity) of the feature surface.
The tolerance zone for the portion of the feature surface indicated is equal to the total allowable movement of a dial indicator positioned normal to the true geometric shape of the feature surface when the part is rotated about the datum axis and the indicator is moved along the portion of the feature surface within the area described by the basic dimensions.
When measuring total run out, the indicator must not be reset when repositioned along the feature surface.
(applies to portion of feature surface indicated)Allowable indicator reading = 0.75 max.
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