1. Glossary of
Terms

2. Feature

3. Feature
- general term applied to a physical
portion of a part

4. Feature - general term applied to a physical portion of a part
- any observable geometry

5. Feature of Size (FOS)

6. Feature of Size (FOS)
- a feature with opposed surface(s)

7. Feature of Size (FOS) - a feature with opposed surface(s)
- may be planar or cylindrical

8. Feature of Size (FOS) - a feature with opposed surface(s)
- may be planar or cylindrical
- is measurable; associated with a
size dimension

9. Examples of Features of Size:

10. Examples of Features of Size:
 Cylindrical FOS

11. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS

12. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole

13. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS

14. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft

15. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS

16. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS

17. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot

18. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot
External Planar FOS

19. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot
External Planar FOS
……….… Tab

20. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot
External Planar FOS
……….… Tab
The uses the term:
Fit Design Analyst TM

21. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot
External Planar FOS
……….… Tab
The uses the term:
Fit Design Analyst TM
- “Hole” as an analog to refer to any internal FOS

22. Examples of Features of Size:
 Cylindrical FOS
Internal Cylindrical FOS
………… Hole
External Cylindrical FOS
……..….. Shaft
 Planar FOS
Internal Planar FOS
………..… Slot
External Planar FOS
……….… Tab
The uses the term:
Fit Design Analyst TM
- “Hole” as an analog to refer to any internal FOS
- “Shaft” as an analog to refer to any external FOS

23. Nominal Size

24. Nominal Size - designation used for the purpose
of general identification

25. Nominal Size - designation used for the purpose
of general identification
- usually expressed in common
fractions

26. Nominal Size - designation used for the purpose
of general identification
- usually expressed in common
fractions 1
Nominal Size is Ø 2

27. Basic Size or Basic Dimension

28. Basic Size or Basic Dimension
the theoretical (ideal) size to which a tolerance is applied

29. Basic Size or Basic Dimension
the theoretical (ideal) size to which a tolerance is applied
limit dimensions result from the application of a tolerance specification to a basic dimension

30. Basic Size or Basic Dimension
the theoretical (ideal) size to which a tolerance is applied

31. Basic Size or Basic Dimension
the theoretical (ideal) size to which a tolerance is applied
Tolerance Specification,
applied to the basic dimension
Basic Dimension

32. Basic Size or Basic Dimension
limit dimensions result from the application of a tolerance specification to a basic dimension

33. Basic Size or Basic Dimension
limit dimensions result from the application of a tolerance specification to a basic dimension
Resulting limit dimensions

34. Basic Hole System

35. Basic Hole System
A widely-used fit system employed when standard tools (e.g., drills, reamers) are used to produce holes

36. Basic Hole System
A widely-used fit system employed when standard tools (e.g., drills, reamers) are used to produce holes
the small hole (lower limit) is assigned the basic size (typically the nominal size), to which the hole tolerance and fit allowance is applied: “the small hole is basic”

37. Basic Hole System
A widely-used fit system employed when standard tools (e.g., drills, reamers) are used to produce holes
the small hole (lower limit) is assigned the basic size (typically the nominal size), to which the hole tolerance and fit allowance is applied: “the small hole is basic”
The toleranced shaft size is then designed around the resulting hole limits in order to achieve the desired fit

38. Basic Shaft System

39. Basic Shaft System
A less widely-used fit system typically employed where shafts are purchased in standard sizes or where two or more fits are required on the same shaft

40. Basic Shaft System
A less widely-used fit system typically employed where shafts are purchased in standard sizes or where two or more fits are required on the same shaft
the large shaft (upper limit) is assigned the basic size to which the shaft tolerance and fit allowance is applied: “the large shaft is basic”

41. Basic Shaft System
A less widely-used fit system typically employed where shafts are purchased in standard sizes or where two or more fits are required on the same shaft
the large shaft (upper limit) is assigned the basic size to which the shaft tolerance and fit allowance is applied: “the large shaft is basic”
The toleranced hole size is then designed around the resulting shaft limits in order to achieve the desired fit

42. LIMITS

43. LIMITS
the maximum and minimum sizes indicated by a toleranced dimension

44. LIMITS
the maximum and minimum sizes indicated by a toleranced dimension
called the “upper limit” (large)
and “lower limit” (small) dimensions

45. Tolerance

46. Tolerance
- the total permissible variation
of a dimension

47. Tolerance - the total permissible variation of a dimension
TOL = UPPER LIMIT DIM - LOWER LIMIT DIM

48. Tolerance
- the total permissible variation of a dimension

49. Tolerance
- the total permissible variation of a dimension
TOL = UPPER LIMIT DIM - LOWER LIMIT DIM
TOL =
.996
TOL =

50. Maximum Material Condition
(MMC)

51. Maximum Material Condition (MMC)
the limit of size of a feature which results in the feature having the maximum amount of material

52. Maximum Material Condition (MMC)
the limit of size of a feature which results in the feature having the maximum amount of material
MMCSHAFT = upper limit (large shaft)

53. Maximum Material Condition (MMC)
the limit of size of a feature which results in the feature having the maximum amount of material
MMCSHAFT = upper limit (large shaft)
MMCHOLE = lower limit (small hole)

54. Least Material Condition
(LMC)

55. Least Material Condition (LMC)
the limit of size of a feature which results in the feature having the minimum amount of material

56. Least Material Condition (LMC)
the limit of size of a feature which results in the feature having the minimum amount of material
LMCSHAFT = lower limit (small shaft)

57. Least Material Condition (LMC)
the limit of size of a feature which results in the feature having the minimum amount of material
LMCSHAFT = lower limit (small shaft)
LMCHOLE = upper limit (large hole)

58. ALLOWANCE

59. ALLOWANCE the minimum clearance (or maximum
interference) between mating features

60. ALLOWANCE the minimum clearance (or maximum
interference) between mating features
the allowance represents "the condition
of tightest permissible fit" between
mating features

61. ALLOWANCE the minimum clearance (or maximum
interference) between mating features
the allowance represents "the condition
of tightest permissible fit" between
mating features
ALLOWANCE = SMALLEST - LARGEST
HOLE SHAFT

62. MEAN DIMENSION

63. MEAN DIMENSION the arithmetic average of the upper and
lower limit dimensions

64. MEAN DIMENSION the arithmetic average of the upper and
lower limit dimensions
the mean dimension is used to create
geometry in computer-aided design (CAD)

65. MEAN DIMENSION the arithmetic average of the upper and
lower limit dimensions
the mean dimension is used to create
geometry in computer-aided design (CAD)
note: the mean dimension is not necessarily equal to the basic dimension

66. End.