151018 GD T Basics Wall Chart

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All drawings made in first angle projection

SYMBOL

NAME

ON DRAWING

TOLERANCE ZONE Two parallel lines 0.03 apart

0.03

Straightness

GAUGING

(Surface)

M

10±0.050 0.03 M

Straightness

(Derived Median Line w/

M

Cylindrical Tolerance Zone 0.03 when Part ∅ = 10.05 0.13 when Part ∅ = 9.95

Cylinder Gauge ID = M + Gauge ID = 10.08

)

Flatness

Two parallel planes 0.030 apart

0.03

FORM

(Surface)

M

Flatness

10±0.05 0.03 M

Cylindricity

ORIENTATION

M +

0.03

Two concentric circles 0.03 apart

0.03

Two concentric cylinders 0.03 apart

A

Two parallel planes 0.03 apart

Flat datum block (Datum A)

A

(Feature)

Datum A

90°

10±0.05 0.03 M A Bonus tolerance

Perpendicularity

Datum A

Two parallel planes 0.03 apart

0.03 A

Gauge Block

A

60°

Datum A

60°

Profile of a line Profile of a surface

0.03 A B B

60°

60

°

Uniform Linear Boundary About True Profile 0.03 apart

Datum B Gauge must follow true profile.

A

Profile is usually measured with a CMM.

Basic dimensions (not shown) must be used to define the True Profile

Datum B

Uniform Surface Boundary About True Profile 0.03 apart

0.03 A B B

Datum A

Gauge must follow true profile.

A

Profile is usually measured with a CMM.

Basic dimensions (not shown) must be used to define the True Profile

Datum A

10±0.05 0.03 A B C

Measure X and Y location and compare to the true position.

Part (actual) position

B

True Position

True

A

10±0.05 0.03 M A B C

B

True X Actual X Actual Pin Position

FUNCTIONAL GAUGING

Part

True position

For an External Feature

Tolerance Zone of Hole Gauge

25.0

25.0

Actual Y True Y

0.03

True center

C

(Maximum Material Condition)

This formula must be less than the ∅ True Position tolerance

Actual

20.0

True Position

2X √ (Actual X - True X)2 + (Actual Y - True Y)2

Y

30.0

LOCATION

Pin Gauge ∅ = 9.92 (9.95 - 0.03)

90°

(Feature of Size w/ M )

Angularity

Pin Gauge OD = M −

Gauge pin inserted perpendicular to datum

Axis Tolerance Zone at M

A

PROFILE

Flat datum block (Datum A)

Datum A

0.03 A

Perpendicularity

= 10.08

Two parallel planes 0.03 apart

0.03 A

Parallelism

M

Gauge spacing at Virtual Condition

(Derived Median Plane w/ M )

Circularity

M

Planar Tolerance Zone

C

A

X

Part

Tolerance Zone of Pin Gauge True position

For an Internal Feature

Actual Hole Position

Gauge

Gauge

1

0.03 A

Concentricity

Datum axis

Datum A Tolerance Zone

A

A

A

0.03 A

A

Measured axis

A Datum A Plane

Symmetry

1

Two parallel planes 0.03 apart

0.03 A

Runout

Datum A Fixed axially + Rotated

A

A

The following is usually done with a CMM: 1. Determine Datum axis 2. Measure referenced surface 3. Determine if central axis falls in TZ

The following is usually done with a CMM: 1. Determine Datum plane 2. Measure both surfaces of features 3. Determine if midpoints fall in TZ

Datum A Fixed + Rotated

RUNOUT

A A

0.03 A

A

Total Runout

A

Datum A Fixed axially + Rotated

Datum A Fixed + Rotated

A A

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