Transcript Reading Plans

Reading Technical
Drawings
Foundations of Manufacturing
Dimensioning Systems
 Four different systems of
dimensioning used in U.S.
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Fractional inch
Decimal inch
Dual dimensioning
SI Metric
Dimensioning Systems
Dimensioning Systems
Dimensioning Systems
Dimensioning Systems
Dimensioning Systems
 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
Scale Reading Quiz 1
Record the
scale length
identified by
1. 3/4
1
Scale Reading Quiz 1
Record the
scale length
2
identified by
2. 1 5/8
Scale Reading Quiz 1
Record the
scale length
3
identified by
3. 2 7/16
Scale Reading Quiz 1
Record the
scale length
identified by
4. 3 3/16
4
Scale Reading Quiz 1
Record the
scale length
identified by
5. 3 15/16
5
Decimal Scales
• Subdivided into units of 1/10, 1/20,
1/50, or 1/100 in.
• 1/50 is sufficient for most
applications
Decimal Scales
• Closer measurements require using micrometer,
vernier or dial calipers
• Major graduations are accented by longer linesusually every 1/10 in.
• Popular scales graduation style has .04 and .06
increments slightly longer than .02 and .08
• Reads faster, more recognizable
Decimal Scales
Decimal Scales
Decimal Scales
Decimal Scales
Scale Reading Quiz 2
Record the
scale length
identified by...
1
1. .80
Scale Reading Quiz 2
Record the
scale length
identified by...
2
2. 1.60
Scale Reading Quiz 2
Record the
scale length
identified by...
3
3. 2.50
Scale Reading Quiz 2
Record the
scale length
identified by...
4
4. 3.32
Scale Reading Quiz 2
Record the
scale length
identified by...
5
5. 3.86
Decimal Dimensioning
• Drawing may be dimensioned
using two- or three-place
decimals
• Amount of tolerance is
determined by number of
decimal places
Decimal Dimensioning
• .50 may have tolerance of ± .01
• .500 may have tolerance of ± .001
• .5000 may have tolerance of
±.0001
Decimal Dimensioning
• Converting fractions to
decimals-results in too many
decimal places
• Need to round off those
numbers to desired places
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 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 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 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 Dimensioning
Decimal Rounding
Quiz
1.
2.
3.
4.
5.
6.
7.
.109 =
.125 =
.156 =
.234 =
.438 =
.547 =
.562 =
.11
.12
.16
.23
.44
.55
.56
Decimal Rounding Quiz
8.
9.
10.
11.
12.
13.
14.
.641 = .64
.797 = .80
.875 = .88
1.056 = 1.06
1.672 = 1.67
2.205 = 2.20
2.454 = 2.45
Decimal Rounding Quiz
15.
16.
17.
18.
19.
20.
3.335 =
3.767 =
5.555 =
6.665 =
7.045 =
8.885 =
3.34
3.77
5.56
6.66
7.04
8.88
Metric Dimensioning
• Metric increment of measure is
millimeter
• Will be noted if different
• Convert a metric dimension to
inches by multiplying it by
.03937
Metric Dimensioning
• Conversion charts are available
to provide converted dimensions
• Metric scales are available and
can be used-eliminating need for
conversion
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
Metric Dimensioning
Scale Reading
Quiz 3
Record the scale
length identified by 1
1. 20 mm
Scale Reading
Quiz 3
Record the scale
2
length identified by
2. 35 mm
Scale Reading
Quiz 3
Record the scale
3
length identified by
3. 51 mm
Scale Reading
Quiz 3
Record the scale
length identified by 4
4. 77.5 mm
Scale Reading Quiz 3
Record the scale
length identified by 5
5. 93.5 mm
Blueprints
 Blueprinting-Term can be interpreted as
 Drawing
 Picture
 Contains information

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
Required sizes
Tolerances
Essential requirements
Notes and instructions
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 Drawings
 Standardized drawings

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“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 Drawings
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 Blocks
 Mechanical drawings may be
reduced to
 Half size
 Quarter size
 One eighth size
Title Blocks
 Mechanical drawings may be
enlarged
 Double
 Four times
 Ten times
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 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
Title Blocks
Title Blocks
Title Blocks
Title Blocks
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
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
Machining
Heat treat
Material
Tolerances
Drawing Notes
• Abbreviations are used in notes
• Keep them brief
Drawing Notes-General
(Example)
• UNLESS OTHERWISE
SPECIFIED
1.
2.
3.
METRIC UNITS ARE
MILLIMETERS
FILS & RNDS ARE .12R
PART SYM ABOUT CL
Single-View Drawings
 Sometimes
adequate to
describe object
 Material
thickness is
listed
Detail Drawings
 “Production drawings” and
“working drawings” are general
terms
 Includes all types of engineering
drawings
Detail Drawings
 Detail drawings include
 Sufficient number of views
 Dimensions
 Notes
 Other pertinent information
Centerlines
Centerlines
 Intersecting centerlines
drawn through each hole
 Used for locationcenterlines are extended
outside view and
dimensions are added
 Radii are the same-often
share a common axiscommon design practice
Diameters and Radii
Diameters and Radii
 Internationally
recognized symbol
for diameter

 Use in place of the
abbreviation DIA
 Number of holes
indicated
Diameters and Radii
 Overall
dimensions can
be calculated
 Remaining
material around
hole can be
calculated
Diameters and Radii
 Remaining
material
around hole
can be
calculated
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
Lines
Drawing is full
size and does
not require a “B”
size drawing
Break Lines
Cylindrical Break
Short Break
Long Break
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
 Indicated by note
 Indicated by view’s centerline
carrying abbreviation
Thermostat
Gasket
1. What is the
part number?
11A001
Thermostat
Gasket
2. What is the
name of the
part?
Thermostat
gasket
Thermostat
Gasket
3. What is the
drawing size?
(A, B, or C)
A
Thermostat
Gasket
4. What scale is
the drawing?
1:1
Thermostat
Gasket
5. Use words to
explain the
answer to
question 4.
Actual size
Thermostat
Gasket
6. How thick is
the part?
.06
Thermostat
Gasket
7. Is the part
symmetrical?
Yes
Thermostat
Gasket
8. Which system of
dimensioning was
used? (Refer to
page 21.)
Decimal
Thermostat
Gasket
9. What is the
fractional
equivalent of the
center hole size?
2 3/16
Thermostat
Gasket
10. What is the
fractional
equivalent of the
mounting hole
spacing? (Refer to
the equivalency
chart, page 25.)
3 5/8
Thermostat
Gasket
11. Calculate the
longest overall
dimension of
the part.
4.24
Thermostat
Gasket
12. Calculate the
overall
dimension of
the part
(height.)
2.88
Thermostat
Gasket
13. Calculate the
material
remaining
between the
large hole and
the nearest
outside edge.
.345
Thermostat
Gasket
14. Calculate the
material
remaining
between the
small hole and
the nearest
outside edge.
.155
Thermostat
Gasket
15. Calculate the
material
remaining
between the
large hole and
the nearest
small hole.
.56