- The document discusses various methods for dimensioning and tolerancing parts in engineering drawings, including dimensioning different geometric shapes, coordinate dimensioning, tabular dimensioning, dual dimensioning, and specifying fits and tolerances. - It explains concepts like maximum material condition, allowance, nominal/basic/actual sizes, and types of fits including clearance, interference, transition, and line fits. - Tables are presented showing how to specify tolerances for holes and shafts based on fit class and size range in both inch and metric systems.

1. Precision Dimensioning
Engineering II

2. Dimensioning Rectangular Prisms

3. Dimensioning Cylinders
• The diameter of
cylinders should be
dimensioned in the
rectangular view
(not the circular
view).
• Cylinders without a
hole passing
through them only
require one view.

4. Dimensioning Cones

5. Dimensioning Spheres

6. Rectangular Coordinate Dimensioning
• Used when computer-controlled production
machines are used to manufacture parts.
• The designer should consult with personnel in
manufacturing to ensure that the origin is
located in an appropriate position.
• Two types of rectangular coordinate
dimensioning:
– Coordinate Dimensioning with Dimension Lines
– Coordinate Dimensioning Without Dimension
Lines

7. Coordinate Dimensioning with
Dimension Lines

8. Coordinate Dimensioning without
Dimension Lines

9. Tabular Dimensioning
• Tabular dimensioning is used when a
series of parts consists of the same
features or geometry but vary in
dimension.
• Letters are used in place of dimension
values, and the values are then placed
in a table.
• Most standard parts are dimensioned
this way in catalogs, the machinery
handbook, and in the back of most
textbooks.

10. Tabular Dimensioning

11. Dual Dimensioning – Position Method
• Millimeter value is placed above (or
below) the inch value or separated by a
dash.

12. Dual Dimensioning – Bracket Method
• Millimeter value is enclosed in square
brackets. A note should be placed on the
drawing such as: DIMENSIONS IN [ ]
ARE MILLIMETERS.

13. Tolerance Dimensioning
• Why do we need tolerance
dimensioning?
– Interchangeable parts manufacturing
– Parts are manufactured at widely separate
localities
– Effective size control
– Modern industry relies on it for
subcontracting and replacement parts
• Accuracy is Expensive, however

14. Reading Dimensions
.1 One tenth of an inch
.01 One hundredth of an inch
.001 One thousandth of an inch
.0001 One ten-thousandth of an inch
.00001 One millionth of an inch

15. Specification of Tolerances
Bilateral-Equal
Limit Dimension
Bilateral-Unequal
Unilateral

16. Tolerance
• Tolerance is the total amount a specific
dimension is permitted to vary
(difference between the maximum and
minimum limits).
• The dimension below has a tolerance of
.0003.

17. Maximum Material Condition
• When specifying tolerance dimensions,
the maximum material condition
(MMC) means the product or part
contains the maximum amount of
material specified by the tolerance.
• The heaviest part.

18. Maximum Material Condition
• For the part shown here the MMC is
1.4996 since that size would yield the
most material.

19. Allowance
• Allowance is the minimum clearance or
maximum interference intended
between the maximum material
condition (MMC) of mating parts.
• The allowance for the system below is:
25.000 - 24.890 = 0.110

20. More Terminology
• Nominal Size - General identification in
fractions (ex. 1-1/2 for 1.500).
• Basic Size - General identification in
decimal (ex. 1.500).
• Actual Size - Measured size.
• Limits - Maximum and minimum sizes
indicated by the tolerance dimensions.

21. Clearance Fit
• Space is always left between parts.
• What is the allowance in this case?
• 1.5000 – 1.4988 = .0012

22. Interference Fit
• Always an interference of material.
• What is the allowance in this case?
• 1.5000 – 1.5013 = -.0013 or just .0013

23. Transition Fit
• Fit might result in clearance or interference.

24. Line Fit
• Clearance or surface contact may result at
assembly.

25. Basic Hole System (Hole Basis)
• The minimum size hole is taken as the basic
size.
• Used when standard tools are used to produce
holes (reamers & broaches).

26. Basic Shaft System (Shaft Basis)
• The maximum shaft size is taken as the basic
size.
• When several parts having different fits, but
one nominal size are required on a single shaft.

27. Specifying a Fit - Inches
Nominal
Size Range
Inches
Over To
Class RC 1
Limits
of
Clear.
Standard
Limits
Hole
H5
Shaft
g4
0-0.12
0.1
0.45
+0.2
–0
–0.1
–0.25
0.12-0.24
0.15
0.5
+0.2
–0
–0.15
–0.3
0.24-0.40
0.2
0.6
+0.25
–0
–0.2
–0.35
0.40-0.71
0.25
0.75
+0.3
–0
–0.25
–0.45
0.71-1.19
0.3
0.95
+0.4
–0
–0.3
–0.55
1.19-1.97
0.4
1.1
+0.4
–0
–0.4
–0.7
• Determine type of fit
and find corresponding
table
• Determine basic size
• Find size range on
table
• Determine tolerances
for Hole and Shaft
• Remember values are
in thousandths of an
inch.

28. Specifying a Fit - Inches
Nominal
Size Range
Inches
Over To
Class RC 1
Limits
of
Clear.
Standard
Limits
Hole
H5
Shaft
g4
0-0.12
0.1
0.45
+0.2
–0
–0.1
–0.25
0.12-0.24
0.15
0.5
+0.2
–0
–0.15
–0.3
0.24-0.40
0.2
0.6
+0.25
–0
–0.2
–0.35
0.40-0.71
0.25
0.75
+0.3
–0
–0.25
–0.45
0.71-1.19
0.3
0.95
+0.4
–0
–0.3
–0.55
1.19-1.97
0.4
1.1
+0.4
–0
–0.4
–0.7
• RC1 - Close Sliding Fit
• Basic size of 1.500
• Upper tolerance on
hole is +0.4, which is
really +0.0004
• Lower tolerance on
hole is -0.
• Upper tolerance on
shaft is -0.0004
• Lower tolerance on
shaft is -0.0007

29. Specifying a Fit - Inches
Nominal
Size Range
Inches
Over To
Class RC 1
Limits
of
Clear.
Standard
Limits
Hole
H5
Shaft
g4
0-0.12
0.1
0.45
+0.2
–0
–0.1
–0.25
0.12-0.24
0.15
0.5
+0.2
–0
–0.15
–0.3
0.24-0.40
0.2
0.6
+0.25
–0
–0.2
–0.35
0.40-0.71
0.25
0.75
+0.3
–0
–0.25
–0.45
0.71-1.19
0.3
0.95
+0.4
–0
–0.3
–0.55
1.19-1.97
0.4
1.1
+0.4
–0
–0.4
–0.7

30. Specifying Fits - Metric
Basic
Size
Loose Running
Hole
H11
Shaft
c11
Fit
1 Max
Min
1.060
1.060
0.940
0.880
0.180
0.060
20 Max
Min
20.130
20.000
19.890
19.760
0.370
0.110
25 Max
Min
25.130
25.000
24.890
24.760
0.370
0.110
• Determine type of fit
and find corresponding
table
• Determine basic size
• Find size range on
table
• Determine tolerances
for Hole and Shaft

31. Specifying Fits - Metric
Basic
Size
Loose Running
Hole
H11
Shaft
c11
Fit
1 Max
Min
1.060
1.060
0.940
0.880
0.180
0.060
20 Max
Min
20.130
20.000
19.890
19.760
0.370
0.110
25 Max
Min
25.130
25.000
24.890
24.760
0.370
0.110
• Loose Running Fit
• Basic size of 25