1. Geometric Dimensioning and Tolerancing
Unit 4 – Position Verification

2. Coordinate Measuring Machine (CMM)
Typical ‘bridge’ CMM is composed of 3 axes.
A touch probe indicates contact with a body.
Typical precision measured in microns or micrometers (10-6 m)

4. CMM

7. Position Tolerance Verification
This unit covers some simple verification techniques for position tolerancing.

8. 3.6 C B A Position Tolerancing Verification Actual Manufactured Part 12 . 5 7 8 1 C B A M
Size of hole is produced
at .750 (MMC).
X² + Y² = Z² - Pythagorean Theorem
2X .005 = Ø.010 Tol Zone
X² + Y² = Z
X² + Y² = Diameter Tol Zone 2
Actual Manufactured
Part
.005
.004
The following slides illustrate how a position tolerance may be verified. The object is not to make everyone experts in inspection but impart some general knowledge on the verification procedure.
The material explains the verification principles of geometric tolerancing. This discussion will prepare the students for the verification exercises they must complete in unit 4. This material is covered at the end of unit 3 or at the beginning of unit 4. To ensure continuity, the Hole Bar in the model set is used to explain the verification principles and then in unit 4 the students will work similar position verification exercises.
1.504
Actual
2.503 Actual
.003
1.500
Let us check this part to see if the hole location is within tolerance.
2.500
3.6

9. Chart that can be used to convert plus/minus values to position tolerance.
See also inch chart on rear cover of pocket guide and metric chart on rear inside cover of pocket guide.
4.7/4.8

10. 3.6 C B A Position Tolerancing Verification Actual Manufactured Part 12 . 5 7 8 1 C B A M
Since the hole is produced at MMC (.750), it is allowed .010 position tolerance. The actual calculated position of the hole falls within the .010 zone.
2X .005 = Ø.010 Tol Zone
Actual Manufactured
Part
.005
.004
The following slides illustrate how a position tolerance may be verified. The object is not to make everyone experts in inspection but impart some general knowledge on the verification procedure.
The material explains the verification principles of geometric tolerancing. This discussion will prepare the students for the verification exercises they must complete in unit 4. This material may be covered at the end of unit 3 or at the beginning of unit 4. To ensure continuity, the hole bar from the model set is used to explain the verification principles and then in unit 4 the students will work similar position verification exercises.
1.504
Actual
2.503 Actual
.003
1.500
2.500
3.6

11. 3.6 C B A Position Tolerancing Verification Actual Manufactured Part 12 . 5 7 8 1 C B A M
Size of hole is produced
at .755.
Let us try another example, this time the hole is produced at .755.
Is the location good or bad?
Actual Manufactured
Part
.005
The following slides illustrate how a position tolerance may be verified. The object is not to make everyone experts in inspection but impart some general knowledge on the verification procedure.
The material explains the verification principles of geometric tolerancing. This discussion will prepare the students for the verification exercises they must complete in unit 4. This material may be covered at the end of unit 3 or at the beginning of unit 4. To ensure continuity, the Hole bar is used to explain the verification principles and then in unit 4 the students will work similar position verification exercises.
1.505
Actual
2.506 Actual
.006
1.500
Let us check this part to see if the hole location is within tolerance.
2.500
3.6

12. 4.7/4.8

13. 3.6 C B A Position Tolerancing Verification 1 8 ± 7 M 2 . 57 8 1 C B A M
If the hole is produced at .755, it is allowed a position tolerance of .015.
The calculations show the hole is produced within a zone, so
the hole location is out by
2X = Ø.0156 Tol Zone
.0078
.005
The following slides illustrate how a position tolerance may be verified. The object is not to make everyone experts in inspection but impart some general knowledge on the verification procedure.
The material explains the verification principles of geometric tolerancing. This discussion will prepare the students for the verification exercises they must complete in unit 4. This material may be covered at the end of unit 3 or at the beginning of unit 4. To ensure continuity, the Hole bar is used to explain the verification principles and then in unit 4 the students will work similar position verification exercises.
1.505
Actual
2.506 Actual
.006
1.500
The above part may be repaired by opening the size of the hole by
2.500
3.6

14. 4.5 Class Exercise Position Verification At MMC- Inch As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
4.5

15. 4.5 MMC =Smallest Hole MMC = Smallest Hole .371 Class Exercise
Position Verification
At MMC- Inch
As drawn
MMC =Smallest Hole
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
MMC = Smallest Hole
.371
4.5

16. 4.5 Actual Size of Hole Actual Size of Hole .371 .376 Class Exercise
Position Verification
At MMC- Inch
As drawn
Actual Size of Hole
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
Actual Size of Hole
.371
.376
4.5

17. 4.5 .005 Position Plus .005 Departure from MMC .010
Class Exercise
Position Verification
At MMC- Inch
As drawn
.005 Position
Plus
.005 Departure from MMC
.010
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
Position + Departure from MMC = .010
.371
.376
.010
4.5

18. 4.5 X Deviation .371 .376 .010 -.004 Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
X Deviation
.371
.376
.010
-.004
4.5

19. 4.5 Y Deviation Y Deviation .371 .376 .010 -.004 +.002 Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
Y Deviation
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
Y Deviation
.371
.376
.010
-.004
+.002
4.5

20. This conversion chart may be found in the workbook as well as on the pocket guide. There are two charts available, one is metric and the other is inch.
4.7

21. 4.5 From Chart .371 .376 .010 -.004 +.002 .0089 Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
From Chart
.371
.376
.010
-.004
+.002
.0089
4.5

22. 4.5 From Chart .371 .376 .010 -.004 +.002 .0089 X Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
From Chart
.371
.376
.010
-.004
+.002
.0089 X
4.5

23. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371

24. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379

25. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379
.013

26. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379
.013
+.004

27. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379
.013
+.004
+.005

28. 4.7

29. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379
.013
+.004
+.005
.0128

30. Class Exercise
Position Verification
At MMC- Inch
As drawn
Produced part
The upper drawing on this slide is the part print. The lower drawing is a produced part and its associated actual measured dimensions. The instructor should use this graphic to explain the procedure to the students.
.371
.376
.010
-.004
+.002
.0089 X
4.5
.371
.379
.013
+.004
+.005
.0128 X

31. POSITION
Hole Verification
at MMC
4.3

32. 4.14 Workshop Exercise 4.6 - Inch
Have the students work the problems and afterwards click thru the slides and provide the answers. Walk around and make sure students are understanding the problems.
4.14

33. Workshop Exercise
4.6 - Inch
4.14