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Blueprint Reading for the Machine Trades, Sixth Edition Unit 2: Dimensioning Systems. Russ Schultz and Larry Smith PowerPoint presentation created by LaVonne Vichlach. Dimensioning Systems. Four different systems of dimensioning used in U.S. and Canada Fractional inch Decimal inch

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blueprint reading for the machine trades sixth edition unit 2 dimensioning systems

Blueprint Reading for the Machine Trades, Sixth Edition Unit 2: Dimensioning Systems

Russ Schultz and Larry Smith

PowerPoint presentation created by LaVonne Vichlach

dimensioning systems
Dimensioning Systems
  • Four different systems of dimensioning used in U.S. and Canada
    • Fractional inch
    • Decimal inch
    • Dual dimensioning
    • SI Metric
slide8
Fractional type steel rules divided into units of:
    • 1/16
    • 1/32
    • 1/64
  • Major graduation accentuated by longer lines
  • Some have small numbers printed adjacent to lines
fractional dimensioning
Fractional Dimensioning
  • Always reduce a fraction to its lowest terms
  • If numerator is even number-it can be reduced
  • Begin your count from a major graduation close to the reading
scale reading quiz 1
Scale Reading Quiz 1

Record the scale length identified by

  • 3/4

1

scale reading quiz 11
Scale Reading Quiz 1

Record the scale length identified by

  • 1 5/8

2

scale reading quiz 12
Scale Reading Quiz 1

Record the scale length identified by

  • 2 7/16

3

scale reading quiz 13
Scale Reading Quiz 1
  • 3 3/16

Record the scale length identified by

4

scale reading quiz 14
Scale Reading Quiz 1
  • 3 15/16

Record the scale length identified by

5

scale reading quiz 15
Scale Reading Quiz 1
  • 13/16

Record the scale length identified by

6

scale reading quiz 16
Scale Reading Quiz 1
  • 1 ¾

Record the scale length identified by

7

scale reading quiz 17
Scale Reading Quiz 1
  • 2 11/16

Record the scale length identified by

8

scale reading quiz 18
Scale Reading Quiz 1
  • 3 17/32

Record the scale length identified by

9

scale reading quiz 19
Scale Reading Quiz 1
  • 3 31/32

Record the scale length identified by

10

decimal scales
Decimal Scales
  • Subdivided into units of 1/10, 1/20, 1/50, or 1/100 in.
  • 1/50 is sufficient for most applications
  • With 50 increments to an inch each increment =.02 in.
  • Reading between increments-capable of determining closest .01 inch measurement
decimal scales1
Decimal Scales
  • Closer measurements require using micrometer, vernier or dial calipers
  • Major graduations are accented by longer lines-usually every 1/10 in.
  • Popular scales graduation style has .04 and .06 increments slightly longer than .02 and .08
  • Reads faster, more recognizable
scale reading quiz 2
Scale Reading Quiz 2
  • .80

Record the scale length identifiedby...

1

scale reading quiz 21
Scale Reading Quiz 2
  • 1.60

Record the scale length identified by…

2

scale reading quiz 22
Scale Reading Quiz 2
  • 2.50

Record the scale length identified by…

3

scale reading quiz 23
Scale Reading Quiz 2
  • 3.32

Record the scale length identified by…

4

scale reading quiz 24
Scale Reading Quiz 2
  • 3.86

Record the scale length identified by…

5

decimal dimensioning
Decimal Dimensioning
  • Drawing may be dimensioned using two- or three-place decimals
  • Amount of tolerance is determined by number of decimal places
decimal dimensioning1
Decimal Dimensioning
  • .50 may have tolerance of ± .01
  • .500 may have tolerance of ± .001
  • .5000 may have tolerance of ±.0001
decimal dimensioning2
Decimal Dimensioning
  • Converting fractions to decimals-results in too many decimal places
  • Need to round off those numbers to desired places
decimal dimensioning3
Decimal Dimensioning
  • Rule #1-When the figure following the last digit to be retained is greater than 5---increase the last number by one
    • .016 becomes .02
    • .047 becomes .05
    • .078 becomes .08
decimal dimensioning4
Decimal Dimensioning
  • Rule #2-When the figure following the last digit to be retained is less than 5---retain the last number
    • .031 becomes .03
    • .062 becomes .06
    • .093 becomes .09
decimal dimensioning5
Decimal Dimensioning
  • Rule #3-When the figure following the last digit to be retained is exactly 5 and the figure to be retained is odd---increase the last number by one
    • .375 becomes .38
    • .875 becomes .88
decimal dimensioning6
Decimal Dimensioning
  • Rule #4-When the figure following the last digit to be retained is exactly 5 and the figure to be retained is even---retain the last number
    • .125 becomes .12
    • .625 becomes .62
decimal dimensioning7
Decimal Dimensioning
  • Rule #3 and #4 are different
    • Established to even numbers as often as possible
    • Even numbers are preferred
    • Decimal numbers divided by two-e.g.-diameter/2 = radius-----results will contain same number of decimal places
decimal rounding quiz
Decimal Rounding Quiz

.11

  • .109 =
  • .125 =
  • .156 =
  • .234 =
  • .438 =
  • .547 =
  • .562 =

.12

.16

.23

.44

.55

.56

decimal rounding quiz1
Decimal Rounding Quiz

.64

  • .641 =
  • .797 =
  • .875 =
  • 1.056 =
  • 1.672 =
  • 2.205 =
  • 2.454 =

.80

.88

1.06

1.67

2.20

2.45

decimal rounding quiz2
Decimal Rounding Quiz

3.34

  • 3.335 =
  • 3.767 =
  • 5.555 =
  • 6.665 =
  • 7.045 =
  • 8.885 =

3.77

5.56

6.66

7.04

8.88

metric dimensioning
Metric Dimensioning
  • Metric increment of measure is millimeter
  • Will be noted if different
  • Dual dimensioning system-SI Metric-used in U.S. and Canada
  • Convert a metric dimension to inches by multiplying it by .03937
metric dimensioning1
Metric Dimensioning
  • Conversion charts are available to provide converted dimensions
  • Metric scales are available and can be used-eliminating need for conversion
metric dimensioning2
Metric Dimensioning
  • Metric scales
    • Have graduations every millimeter of half-millimeter
    • Designated “mm” or “1/2 mm”
    • Every fifth millimeter is accentuated by a longer line
    • Every tenth millimeter is identified by a number
scale reading quiz 3
Scale Reading Quiz 3

Record the scale length identified by

  • 20 mm

1

scale reading quiz 31
Scale Reading Quiz 3

Record the scale length identified by

2

  • 35 mm
scale reading quiz 32
Scale Reading Quiz 3

Record the scale length identified by

3

  • 51 mm
scale reading quiz 33
Scale Reading Quiz 3
  • 77.5 mm

Record the scale length identified by

4

scale reading quiz 34
Scale Reading Quiz 3
  • 93.5 mm

Record the scale length identified by

5

blueprints
Blueprints
  • Blueprinting-Term can be interpreted as
    • Drawing
    • Picture
  • Contains information
    • Required sizes
    • Tolerances
    • Essential requirements
    • Notes and instructions
engineering drawings
Engineering Drawings
  • Original drawing made by drafter or engineer
  • Prints are referred to as engineering drawings
  • Also referred to as blueprints (more common term)
engineering drawings1
Engineering Drawings
  • Standardized drawings
    • “A” size is 8 ½ x 11 inches
    • “B” size is 11 x 17 inches
    • “C” size is 17 x 22 inches
    • “D” size is 22 x 34 inches
    • “E” size is 34 x 44 inches
engineering drawings3
What are the basic dimensions of the A-size drawing?Engineering Drawings

8 ½ X 11

2. If C-size is twice as large as B-size, how much larger is it than A-size?

4X

engineering drawings4
Will an E-size print fold to fit in the same envelope with an A-size print?

A2

Engineering Drawings

YES

4. What metric size is twice as large as the A3 size?

title blocks
Title Blocks
  • Each drawing contains a Title Block
    • Drawing number is most prominent lettering in title block
    • Lettered larger to stand out
    • Scale determines the size of the object drafted
title blocks1
Title Blocks
  • Mechanical drawings may be reduced to
    • Half size
    • Quarter size
    • One eighth size
title blocks2
Title Blocks
  • Mechanical drawings may be enlarged
    • Double
    • Four times
    • Ten times
title blocks3
Title Blocks
  • Half scale---1/2, 1:2, or ½”=1”
  • Twice scale-2/1, 2:1, 2-1, 2”=1” or 2X
  • Arrangement of numerals indicates relationship
title blocks4
Title Blocks
  • Refer to scale as the “Do Scale”
    • “D” stands for the drawing
    • “O” stands for the object
    • Sale of 1:2 means
      • The drawing is 1 inch
      • Object is 2 inches
    • A “Do Scale” of 2:1 means
      • The drawing is 2 inches
      • The object is one inch or one half the drawing size
drawing notes
Drawing Notes
  • Local notes-apply to specific item or area
    • Use leaders
    • Direct notes to point of application
  • General notes apply to whole drawing or product
    • Machining
    • Heat treat
    • Material
    • Tolerances
drawing notes1
Drawing Notes
  • Abbreviations are used in notes
  • Keep them brief
drawing notes general
UNLESS OTHERWISE SPECIFIED

METRIC UNITS ARE MILLIMETERS

FILS & RNDS ARE .12R

PART SYM ABOUT CL

Drawing Notes-General
drawing notes local
5 HOLES EQL SP ON 6.000BC

.344 DR, .500 CBORE, .30 DP

.281 DR, 82° CSK, .53 DIA

Drawing Notes-Local
drawing notes quiz
Drawing Notes Quiz
  • What type of note applies to an entire drawing?

General

drawing notes quiz1
Drawing Notes Quiz
  • What type of line is used with local notes?

Leader

drawing notes quiz2
Drawing Notes Quiz
  • Where do general notes appear on a drawing?

Above the title block

drawing notes quiz3
Drawing Notes Quiz
  • Interpret the abbreviations SYM and CL used in the third general note.

Symmetrical and centerline

drawing notes quiz4
Drawing Notes Quiz
  • Interpret the abbreviations DR and CSK used in the third local note.

Drill and countersink

single view drawings
Single-View Drawings
  • Sometimes adequate to describe object
  • Material thickness is listed
detail drawings
Detail Drawings
  • “Production drawings” and “working drawings” are general terms
  • Includes all types of engineering drawings
detail drawings1
Detail Drawings
  • Detail drawings include
    • Sufficient number of views
    • Dimensions
    • Notes
    • Other pertinent information
centerlines1
Centerlines
  • Intersecting centerlines drawn through each hole
  • Used for location-centerlines are extended outside view and dimensions are added
  • Radii are the same-often share a common axis-common design practice
diameters and radii1
Diameters and Radii
  • Internationally recognized symbol for diameter
  • Use in place of the abbreviation DIA
  • Number of holes indicated
diameters and radii2
Diameters and Radii
  • Overall dimensions can be calculated
  • Remaining material around hole can be calculated
diameters and radii3
Diameters and Radii
  • Remaining material around hole can be calculated
thermostat gasket
Thermostat Gasket

1. What is the part number?

11A001

thermostat gasket1
Thermostat Gasket

2. What is the name of the part?

Thermostat gasket

thermostat gasket2
Thermostat Gasket

3. What is the drawing size? (A, B, or C)

A

thermostat gasket3
Thermostat Gasket

4. What scale is the drawing?

1:1

thermostat gasket4
Thermostat Gasket

5. Use words to explain the answer to question 4.

Actual size

thermostat gasket5
Thermostat Gasket

6. How thick is the part?

.06

thermostat gasket6
Thermostat Gasket

7. Is the part symmetrical?

Yes

thermostat gasket7
Thermostat Gasket

8. Which system of dimensioning was used? (Refer to page 21.)

Decimal

thermostat gasket8
Thermostat Gasket

9. What is the fractional equivalent of the center hole size? (Refer to the equivalency chart, page 25.)

2 3/16

thermostat gasket9
Thermostat Gasket
  • What is the fractional equivalent of the mounting hole spacing? (Refer to the equivalency chart, page 25.)

3 5/8

thermostat gasket10
Thermostat Gasket

11. Calculate the longest overall dimension of the part.

4.24

thermostat gasket11
Thermostat Gasket

12. Calculate the overall dimension of the part (height.)

2.88

thermostat gasket12
Thermostat Gasket

13. Calculate the material remaining between the large hole and the nearest outside edge.

.345

thermostat gasket13
Thermostat Gasket

14. Calculate the material remaining between the small hole and the nearest outside edge.

.155

thermostat gasket14
Thermostat Gasket

15. Calculate the material remaining between the large hole and the nearest small hole.

.56

break lines
Break Lines
  • Permits removal of a portion of view
  • Paper size is smaller
  • Drawing scale can get smaller
  • Portion removed must be uniform in shape
break lines1
Break Lines

Drawing is full size and does not require a “B” size drawing

typical dimensions
Typical Dimensions
  • Entered after a dimension
  • Means all other similar dimensions are same as one marked “TYP”
  • Eliminates repetition of dimensions
  • Saves on drawing space
symmetry
Symmetry
  • Indicated by note
  • Indicated by view’s centerline carrying abbreviation
exercise
Exercise

Enter dimensions for the letters provided.

bottom plate12
Bottom Plate

1. What type of line was drawn to indicate symmetry?

Centerline

bottom plate13
Bottom Plate

2. What word is abbreviated TYP?

Typical

bottom plate14
Bottom Plate

3. What is the thickness of the plate?

.25

bottom plate15
Bottom Plate

4. How many round holes does the plate contain?

10

bottom plate16
Bottom Plate

5. What is the fractional equivalent of the small hole diameter?

9/32

bottom plate17
Bottom Plate

6. How much material remains between a .62 Dia. hole and the nearest outside edge?

.25

bottom plate18
Bottom Plate

7. How much material remains between a .28 Dia. hole and the nearest outside edge?

.16

bottom plate19
Bottom Plate

8. Calculate the longest overall dimension of the plate.

6.76

tolerances
Tolerances
  • Tolerances are assigned to every dimension
  • Assign maximum acceptable deviation-tolerance
  • Shown with dimension
  • Shown in the title block as a general tolerance
tolerances1
Tolerances
  • General tolerances commonly assigned using decimals
  • Decimal dimension and tolerance have same number of places
  • Most commonly expressed bilaterally-not always equal in both directions
tolerance quiz
Tolerance Quiz

1. What is the two place decimal tolerance in Example A?

 .03

tolerance quiz1
Tolerance Quiz

2. What is the tolerance for drilled holes in Example A?

+ .010

-.002

tolerance quiz2
Tolerance Quiz

3. What is the three-place decimal tolerance in Example B?

 .004

tolerance quiz3
Tolerance Quiz

4. What is the fractional tolerance in Example C?

 1/64

tolerance quiz4
Tolerance Quiz

5. What is the total tolerance for the two-place decimal inch in Example A?

 .03

tolerance quiz5
Tolerance Quiz
  • What is the angular tolerance in Example C?

 030’

tolerance quiz6
Tolerance Quiz
  • What is the total tolerance for the three-place decimal inch in Example B?

 .004

tolerance quiz7
Tolerance Quiz
  • What is the total tolerance for drilled holes in Example A?

+ .010

-.002

bolt circles
Bolt Circles
  • Three or more holes are positioned around a common center
  • Located angularly on a circular centerline
bolt circles1
Bolt Circles
  • Dimension of bolt circle appears
    • Inside of diagonal dimension line
    • With abbreviation BC after hole data
    • Holes may be equally spaced
    • Abbreviation EQL SP follows quantity in local note
    • Divide 360 by number of holes
    • One of the holes is on vertical or horizontal centerline
bolt circles2
Bolt Circles
  • Inside of diagonal dimension line
bolt circles3
Bolt Circles
  • Inside of diagonal dimension line
bolt circles4
Bolt Circles
  • With abbreviation BC after hole data-Holes may be equally spaced
  • Abbreviation EQL SP follows quantity in local note
bolt circles5
Bolt Circles
  • Holes may be located coordinately
  • Use only vertical or horizontal dimensions
slide152
Shim
  • How thick is the shim?

.020

slide153
Shim
  • Is the shim symmetrical?

No

slide154
Shim
  • Are the bolt circles concentric?

Yes

slide155
Shim
  • How many holes are in the shim?

8

slide156
Shim
  • What is the tolerance on the .250 Dia. holes?

.005

slide157
Shim
  • What is the tolerance on the .500 Dia. holes?

.008

slide158
Shim
  • What is the tolerance on the 1.000 Dia. hole?

.010

slide159
Shim
  • What is the tolerance on the bolt circles?

.010

slide160
Shim
  • What is the tolerance on the radii?

.02

slide161
Shim
  • How much material is between the 5/8” hole and the nearest outside edge?

.1875

slide162
Shim
  • How far apart angularly are the three .500 Dia. holes?

120°

slide163
Shim
  • How far apart angularly are a .250 Dia. hole and the nearest .500 Dia. hole?

60°

slide164
Shim
  • How far apart angularly are a .250 Dia. hole and the farthest .500 Dia. hole?

180°

slide165
Shim
  • How far apart angularly is the 5/8” hole from the nearest ½” hole?

30°

slide166
Shim
  • What is the angular tolerance for the hole locations?

±0°30’

slide167
Shim

What is the dimension for A?

1.15

slide168
Shim

What is the dimension for B?

1.125

slide169
Shim

What is the dimension for C?

.625

slide170
Shim

What is the dimension for D?

.525

slide171
Shim

What is the dimension for E?

.275

maximum least material condition
Maximum & Least Material Condition
  • MMC
  • Feature of size contains the maximum material within assigned tolerances
maximum least material condition1
Maximum & Least Material Condition
  • For a shaft
    • At MMC when tolerance is added to its size dimension (.760)
    • At LMC when tolerance is subtracted from it size dimension (.740)
maximum least material condition2
Maximum & Least Material Condition
  • Internal feature-hole-is at MMC when it is at its smallest size

Sizes are exaggerated. NTS-Not To Scale

maximum least material condition3
Maximum & Least Material Condition
  • Internal feature-hole-is at LMC when it is at its largest size

Sizes are exaggerated. NTS-Not To Scale

maximum least material condition4
Maximum & Least Material Condition
  • On any part
    • All surfaces are features (they are not measurable-size)
    • For LMC and MMC, the feature must have a size dimension
    • Must be associated with tow opposing elements or two opposed parallel surfaces
    • Must be measurable
slide178

1.005

.995

slide179

3.005

2.995

slide180

1.30

1.32

slide181

.349

.339

slide182

.30

.32

slide183

.66

.64

slide186

.905

.895

slide187

1.91

1.89

slide189

.258

.248

slide190

.370

.380

allowance
Allowance
  • Minimum clearance between mating parts
  • Maximum interference between mating parts
  • Calculate by subtracting MMC of shaft from MMC of hole
allowance1
Allowance
  • When shaft’s MMC is smaller than hole’s MMC-positive allowance-clearance
  • When shaft’s MMC is larger than hole’s MMC-negative allowance-interference
allowance2
Allowance
  • Positive or negative-allowance is always the tightest possible fit between mating parts
allowance3
Allowance

Use the formula for calculating allowance:

MMC Hole - MMC Shaft = Allowance

allowance4
Allowance

MMC Hole =.999

-MMC Shaft A =.998

Allowance =.001 (positive)

allowance5
Allowance

MMC Hole =.999

-MMC Shaft B =1.004

Allowance =-.005 (negative)

arcs and circles
Arcs And Circles
  • When an arc is less than a complete circle-dimension it by radius
  • May have a definite center-e.g.. 1.00R & 4.50R in Dwg. 11A004
  • May float-run tangent with other arcs or lines-e.g. .75R same print
arcs and circles1
Arcs And Circles
  • Radial dimension not used for circles or diameters
  • Radial dimension doubles permit greater variation
arcs and circles2
Arcs And Circles
  • E.g. 1.000 DIA with .01 yields dimension between .99 and 1.01 DIA
  • .50R with .01 would permit diametric dimensions between .98 and 1.02 DIA
arcs and circles4
Arcs And Circles
  • Is the print drawn to (a) half-size or (b) twice-size?

(a) half-size

arcs and circles5
Arcs And Circles
  • What is the thickness of the spacer?

.500

arcs and circles6
Arcs And Circles
  • Interpret the abbreviation CRS used in the title block?

Cold-Rolled Steel

arcs and circles7
Arcs And Circles
  • How many holes does the spacer contain?

10

arcs and circles8
Arcs And Circles
  • Is the spacer symmetrical about the vertical and horizontal centerline?

Vertical

arcs and circles9
Arcs And Circles
  • What is the angular dimension between each small hole?

60

arcs and circles10
Arcs And Circles
  • What is the angular dimension between each large hole?

120

arcs and circles11
Arcs And Circles
  • What tolerance is assigned to the angular spacing of the drilled holes?

 030’

arcs and circles12
Arcs And Circles
  • What is the tolerance on the bolt circles?

 .01

arcs and circles13
Arcs And Circles
  • What is the tolerance on the center hole diameter?

 .005

arcs and circles14
Arcs And Circles
  • What is the MMC of the center hole?

4.995

arcs and circles15
Arcs And Circles
  • What is the tolerance on the drilled holes?

+.010

-.002

arcs and circles16
Arcs And Circles
  • What is the MMC of the .688 holes?

.686

arcs and circles17
Arcs And Circles
  • What is the overall dimension along the horizontal CL?

9.00

arcs and circles18
Arcs And Circles
  • What is the overall dimension along the vertical CL?

10.50

arcs and circles19
Arcs And Circles

Enter the dimension for the letter “A.”

.50

arcs and circles20
Arcs And Circles

Enter the dimension for the letter “B.”

.531

arcs and circles21
Arcs And Circles

Enter the dimension for the letter “C.”

1.00

arcs and circles22
Arcs And Circles

Enter the dimension for the letter “D.”

.656

arcs and circles23
Arcs And Circles

Enter the dimension for the letter “E.”

.687

arcs and circles24
Arcs And Circles

Enter the dimension for the letter “A.”

.81

arcs and circles25
Arcs And Circles

Enter the dimension for the letter “B.”

2.32

arcs and circles26
Arcs And Circles

Enter the dimension for the letter “C.”

.15

arcs and circles27
Arcs And Circles

Enter the dimension for the letter “D.”

3.28

arcs and circles28
Arcs And Circles

Enter the dimension for the letter “E.”

7.26

arcs and circles29
Arcs And Circles

Enter the dimension for the letter “F.”

1.72

arcs and circles30
Arcs And Circles

Enter the dimension for the letter “G.”

1.58

arcs and circles31
Arcs And Circles

Enter the dimension for the letter “H.”

.42

arcs and circles32
Arcs And Circles

Enter the dimension for the letter “I.”

30°

arcs and circles33
Arcs And Circles

Enter the dimension for the letter “J.”

3.98

arcs and circles34
Arcs And Circles

Enter the dimension for the letter “K.”

.01

arcs and circles35
Arcs And Circles

Enter the dimension for the letter “L.”

.20

arcs and circles36
Arcs And Circles

Enter the dimension for the letter “M.”

.19

arcs and circles37
Arcs And Circles

Enter the dimension for the letter “N.”

.12

arcs and circles38
Arcs And Circles

Enter the dimension for the letter “0.”

.30

arcs and circles39
Arcs And Circles
  • How much material remains between a .250 hole and the outside edge?

.225

arcs and circles40
Arcs And Circles
  • How much material remains between a .220 hole and the outside edge?

.19

arcs and circles41
Arcs And Circles
  • Are the .200 holes located in the exact center between ID and OD? (Calculate this.)

No

arcs and circles42
Arcs And Circles
  • What is the MMC of the center hole?

2.555

arcs and circles43
Arcs And Circles
  • What is the MMC of the .250 holes?

.248

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