GD&T Document

DIMENSIONAL ENGINEERING

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Course Outline 1. Introduction 2. Symbols 3. Terms 4. General Rules 5. Datum's 6. Form Control 7. Orientation controls 8. Location controls 9. Run-out

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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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Symbols Symbols 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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Feature control Frame

Geometric Characteristic symbol

Geometric tolerance

Primary Datum

Primary Datum

Geometric tolerance zone

Datum Modifier

Tertiary Datum

Modifier

10

Feature control Frame attached to features

11

GD&T Symbology

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Terms Basic 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 dimension and a size tolerance. FOS is •Cylindrical surface •Two opposed parallel surfaces •A special Surface •Two opposite line elements

have

a

13

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

Internal Features

VC = MMC + Geo. Tol. at MMC

VC = MMC - Geo. Tol. at MMC

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Datum Plane

15

Maximum Material Condition

External Features (Pins) Actual Feature Size

MMC

Bonus (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

MMC

Bonus (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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Rules Rule#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 .020 drawing above:_________

2.

If the pins is produced at a dia. 1.010, it must be .010 straight within the tolerance? _______

3.

If the pins is produced at a dia. 1.015, it must be .005 straight within the tolerance? _______

4.

If the pins is produced at a dia. 1.020, it must be 0 straight within the tolerance? _______

5.

If the pins is produced at a dia. 1.000, it must be .020 straight within the tolerance? _______ 19

Rule#5

Virtual condition Calculation

Internal Features

External Features

MMC

1.010

1.025

Geometric Tolerance

-.010

+ .010

Virtual Condition

1.000

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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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

Datum feature selection Datum features are selected to meet design requirements: They should be:  Functional surfaces  Mating surfaces  Readily accessible  Repeatable 22

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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Datum Quiz True or False A Datum is theoretically exact geometric reference.

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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Establish Datum's

A

D

A

B

B

C

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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)

MMC Perfect Form Boundary

25.1 (LMC)

Internal Feature of Size

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Extreme Variations of Form Allowed By Size Tolerance 25 24.9

24.9 (LMC)

25 (MMC)

24.9 (LMC) MMC Perfect Form Boundary

25 (MMC)

24.9 (LMC)

External Feature of Size

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Straightness (Flat Surfaces) 0.5

0.1

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 31

Straightness (Flat Surfaces) 0.5 Tolerance Zone

24.75 min

25.25 max

0.1 Tolerance Zone

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.

traightness tolerance is applied in the view where the ents to be controlled are represented by a straight line

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Straightness (Surface Elements) 0.1

0.1 Tolerance Zone MMC

0.1 Tolerance Zone MMC

0.1 Tolerance Zone MMC

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. 33

Straightness (RFS) 0.1

0.1 Diameter Tolerance Zone MMC

Outer Boundary (Max)

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 0.1

15 (MMC)

M

0.1 Diameter Tolerance Zone

15.1 Virtual Condition 14.85 (LMC)

0.25 Diameter Tolerance Zone

15.1 Virtual Condition 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. 35

Flatness 0.1

25 +/-0.25

0.1 Tolerance Zone 0.1 Tolerance Zone

24.75 min

25.25 max

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.

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. 36

Circularity (Roundness) 0.1

90 0.1

90

0.1 Wide Tolerance Zone

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.

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

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Cylindricity 0.1

0.1 Tolerance Zone

MMC

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.

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. 38

Orientation controls

Angularity

Perpendicularity

Parallelism

39

Angularity (Feature Surface to Datum Surface) 20 +/-0.5 0.3 A 30

o

A 19.5 min

20.5 max

30

A

0.3 Wide Tolerance Zone

o

30

A

o

0.3 Wide Tolerance Zone

The tolerance zone in this example is defined by two parallel planes oriented at the specified angle to the datum reference plane.

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. 40

Angularity (Feature Axis to Datum Surface) NOTE: Tolerance applies to feature at RFS 0.3 A

0.3 Circular Tolerance Zone

0.3 Circular Tolerance Zone

60

A

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.

A

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. 41

Angularity (Feature Axis to Datum Axis) NOTE: Feature axis must lie within tolerance zone cylinder

0.3 A

NOTE: Tolerance applies to feature at RFS

A

0.3 Circular Tolerance Zone

0.3 Circular Tolerance Zone 45 o

Datum Axis A 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.

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. 42

Perpendicularity (Feature Surface to Datum Surface) 0.3 A

A 0.3 Wide Tolerance Zone

A

0.3 Wide Tolerance Zone

The tolerance zone in this example is defined by two parallel planes oriented perpendicular to the datum reference plane.

A

Perpendicularity is the condition of the planar feature surface at a right angle to the datum reference plane, within the specified tolerance zone. 43

Perpendicularity (Feature Axis to Datum Surface) 0.3 Diameter Tolerance Zone

0.3 Circular Tolerance Zone

C

NOTE: Tolerance applies to feature at RFS

0.3 Circular Tolerance Zone 0.3 C

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.

Perpendicularity is the condition of the feature axis at a right angle to the datum reference plane, within the specified tolerance zone. 44

Perpendicularity (Feature Axis to Datum Axis) NOTE: Tolerance applies to feature at RFS 0.3 A

A

0.3 Wide Tolerance Zone

Datum Axis A 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. 45

Parallelism (Feature Surface to Datum Surface)

0.3 A

25 +/-0.5

A 0.3 Wide Tolerance Zone

25.5 max

0.3 Wide Tolerance Zone

24.5 min

A

The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.

A

Parallelism is the condition of the planar feature surface equidistant at all points from the datum reference plane, within the specified tolerance zone. 46

Parallelism (Feature Axis to Datum Surface) NOTE: The specified tolerance does not apply to the orientation of the feature axis in this direction

NOTE: Tolerance applies to feature at RFS

0.3 Wide Tolerance Zone

0.3 A

A

The tolerance zone in this example is defined by two parallel planes oriented parallel to the datum reference plane.

A

Parallelism is the condition of the feature axis equidistant along its length from the datum reference plane, within the specified tolerance zone. 47

Parallelism (Feature Axis to Datum Surfaces) 0.3 Circular Tolerance Zone

B NOTE: Tolerance applies to feature at RFS 0.3 Circular Tolerance Zone

0.3 Circular Tolerance Zone 0.3 A B

B

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 planes.

A

Parallelism is the condition of the feature axis equidistant along its length from the two datum reference planes, within the specified tolerance zone. 48

Parallelism (Feature Axis to Datum Axis) 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 0.1 Circular Tolerance Zone

0.1 A

A

0.1 Circular Tolerance Zone

Datum Axis A

Parallelism is the condition of the feature axis equidistant along its length from the datum reference axis, within the specified tolerance zone. 49

Location Controls

True Position

Concentricity

Symmetry

50

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 surfaces Mating surfaces Readily accessible Repeatable 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

Internal Features

VC = MMC + Geo. Tol. at MMC

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. 51

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.

52

MMC

External Features (Pins) Actual Feature Size

MMC

Bonus (Difference)

Geometric Tolerance

Total Position Tolerance

.800

.800

.000

.020

.020

.790

.800

.010

.020

.030

.780

.800

.020

.020

.040

.770

.800

.030

.020

.050

Internal Features (Holes) Actual Feature Size

MMC

Bonus (Difference)

Geometric Tolerance

Total Position Tolerance

.800

.770

.030

.020

.050

.790

.770

.020

.020

.040

.780

.770

.010

.020

.030

.770

.770

.000

.020

.020 53

Zero Positional Tolerance

54

Zero Positional Tolerance- Exercise

4 X .750 - .830

φ .000M

A

B C

55

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.

56

57

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 58

Multiple Patterns of the feature

SEPARATE REQUIREMENT

SEPARATE REQUIREMENT

59

Location Tolerance

 What are the tolerances for datum hole D if produced at φ .525: Location .015 + .010 = .025 .015 + .002 = .017 tolerance ? __________ Orientation tolerance? ______________ .500 .508 Virtual conditions are, Location:_______ Orientation___________  What are the tolerances for the 4Xφ .380 holes if produced at φ .415 .040 .040 .375 Location:_______ Orientation_______ Virtual Condition__________  For datum hole (D), what datum (s) determine (s) A B&C Orientation:___________ Location:____________  For the φ .380 hole pattern what datum (s) determine (s) A D B Orientation:__________ Location: __________Clocking:_________  If the gauge is used to check the φ .380 hole pattern: Datum D pin should .510 - .002 = .508 be at what diameter_________ .375

The gauge pins for the φ .380 holes should be of dia:________ 60

Composite Positional Tolerance 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.

61

Location (Concentricity) Datum Features at RFS 6.35 +/- 0.05 0.5 A

A

15.95 15.90

As Shown on Drawing Means This:

Axis of Datum Feature A

0.5 Coaxial Tolerance Zone

Derived Median Points of Diametrically Opposed Elements 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. 62

Location (Symmetry) Datum Features at RFS 6.35 +/- 0.05 0.5 A

A

15.95 15.90

As Shown on Drawing Means This:

Center Plane of Datum Feature A

0.5 Wide Tolerance Zone

Derived Median Points 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. 63

Runout

Circular Run out

Total Run out

64

Features Applicable to Run out Tolerance Internal surfaces constructed around a datum axis

External surfaces constructed around a datum axis Datum axis (established from datum feature

Datum feature

Angled surfaces constructed around a datum axis

Surfaces constructed perpendicular to a datum axis 65

Circular Run out Total Tolerance

Maximum

Circular run out can only be applied on an RFS basis and cannot be modified to MMC or LMC.

Minimum

Full Indicator Movement Maximum Reading

+

Minimum Reading 0

-

Measuring position #1 (circular element #1)

Full Part Rotation

Measuring position #2 (circular element #2)

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). 66

Circular Run out (Angled Surface to Datum Axis) 0.75 A A

50 +/-0.25 50

Means This: Allowable indicator reading = 0.75 max. Full Indicator Movement

(

) -

0

+

o

+/- 2

o

As Shown on Drawing 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. Collect or Chuck

When measuring circular runout, the indicator must be reset when repositioned along the feature surface.

Datum axis A

360 o Part Rotation

Single circular element

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 67

Circular Run out (Surface Perpendicular to Datum Axis) 0.75 A A

50 +/-0.25

As Shown on Drawing Means This:

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 rotated 360 degrees about the datum axis. The tolerance limit is applied independently to each individual measuring position along the feature surface. -

360 o Part Rotation

0

+

When measuring circular run out, the indicator must be reset when repositioned along the feature surface. Allowable indicator reading = 0.75 max.

Datum axis A 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 68

Circular Run out (Surface Coaxial to Datum Axis) 0.75 A A

50 +/-0.25

As Shown on Drawing Means This:

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.

0

-

When measuring circular run out, the indicator must be reset when repositioned along the feature surface.

Single circular element 360 o Part Rotation

Datum axis A

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

69

Circular Run out (Surface Coaxial to Datum Axis) 0.75 A-B

A

B

As Shown on Drawing Means This:

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.

Machine center

0

-

When measuring circular run out, the indicator must be reset when repositioned along the feature surface.

Single circular element Datum axis A-B

360 o Part Rotation

Machine center 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

70

Circular Run out (Surface Related to Datum Surface and Axis) A

B

0.75 A B 50 +/-0.25

As Shown on Drawing 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:

Single circular element

Allowable indicator reading = 0.75 max.

360 o Part Rotation

+

0

Stop collar -

Collets or Chuck

Datum axis B

When measuring circular run out, the indicator must be reset when repositioned along the feature surface.

Datum plane A 71

Total Run out Total Tolerance

Maximum

Total run out can only be applied on an RFS basis and cannot be modified to MMC or LMC.

Minimum

Full Indicator Movement Maximum Reading

Minimum Reading

+

0

-

Indicator Path

Full Part Rotation

+

0

-

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). 72

Total Run out (Angled Surface to Datum Axis) 0.75 A A

50 +/-0.25 50

o

+/- 2

Means This: When measuring total run out, the indicator must not be reset when repositioned along the feature surface.

-

0

+

0

+

o

As Shown on Drawing 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. Allowable indicator reading = 0.75 max. (applies to the entire feature surface)

Collets or Chuck

Full Part Rotation

Datum axis A

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 73

Total Run out (Surface Perpendicular to Datum Axis) 0.75 A

10 35

50 +/-0.25

A

Means This:

10 35 Full Part Rotation

As Shown on Drawing

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.

-

0

-

0

+ +

When measuring total run out, the indicator must not be reset when repositioned along the feature surface.

Allowable indicator reading = 0.75 max. (applies to portion of feature surface indicated)

Datum axis A 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. 74

THANK YOU

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