Transcript chapter 2

CHAPTER 2
Drafting Equipment, Media,
and Reproduction Methods
Learning Objectives
• Describe and demonstrate the use of
manual drafting equipment and
supplies
• Explain the concept of drawing scale,
and identify common inch and metric
scales
• Read metric, civil engineer, architect,
and mechanical scales
Learning Objectives
• Describe and use drafting media, sheet
sizes, and sheet blocks and symbols
• Explain common drawing reproduction
methods
Manual Drafting (Hand Drafting)
• Mostly replaced by computer-aided
design and drafting (CADD)
• Manual drafting and CADD require
understanding the basics of drafting
• Scale
• Sheet size
• Sheet format
Manual Drafting Equipment and
Supplies
• Historical reference
• Still valuable for:
• Sketching
• Taking measurements
• Other related activities
• Still used by some companies for
certain applications
Automatic Pencils
• Common for manual drafting,
sketching, and office use
• Do not require sharpening
• Available in several different lead sizes
• Combination of 0.5, 0.7, and 0.9 mm
pencils and leads good for sketching
and daily use
Lead Grades
• Different grades of hardness for
specific techniques
• 2H and H good for typical daily office use
• 2H to F for thick lines
• 4H to H for thin lines
• 6H or 4H for construction lines and
guidelines
Compasses
• Especially useful
for large circles
and arcs
• More time
consuming than a
template
• Bow compass
(shown)
Dividers
• Bow
• Proportional
Parallel Bar
• Draw horizontal lines
• Use triangles to draw vertical lines and
angles
Triangles
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Straightedge
Draw angles
Connect points
30°–60° triangle
• Angles of 30°–60°–90°
• 45° triangle
• Angles of 45°–45°–90°
Templates
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Circles
Ellipses
Letters
Specific requirements and drafting
disciplines
• Examples:
 Architectural
symbols
 Electronic schematic symbols
Irregular Curves
• Have no constant radii
• French and flexible curves
• Radius curve
Drafting Machines
• Generally take the place of triangles
and parallel bars
• Maintains a horizontal and vertical
relationship between scales
• Scales serve as straightedges
• Protractor allows scales to be set
quickly at any angle
Arm and Track Drafting Machines
Scale
• Measurement instrument
• Specific scales for mechanical,
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architectural, civil, and metric drawings
Used by manual drafters to help create
scaled drawings
Still useful for sketching, taking
measurements, and related tasks
Four basic shapes
Scale
• Concept
• A universal and critical design and drafting
concept
Drawing Scale
• Drawings are scaled so the objects
represented can be illustrated clearly
on standard sizes of paper
• Depends on:
• Actual size of the objects drawn
• Amount of detail to show
• Media size
• Amount of dimensioning and notes
required
Inch Mechanical Drawing Scales
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Full scale = FULL or 1:1
Half scale = HALF or 1:2
Quarter scale = QUARTER or 1:4
Twice scale = DOUBLE or 2:1
Four times scale = 4:1
Ten times scale = 10:1
Drawing Scale
Metric Mechanical Drawing Scales
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Full scale = 1:1
Half scale = 1:2
One fifth scale = 1:5
One twenty-fifth scale = 1:25
One thirty-three and one-third scale =
1:33 1/3
• One seventy-fifth scale = 1:75
U.S. Customary Architectural
Drawing Scales
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1/8" = 1'–0"
1/4" = 1'–0"
1/2" = 1'–0"
1" = 1'–0"
1 1/2" = 1'–0"
3" = 1'–0"
U.S. Customary Civil Drawing
Scales
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1" =
1" =
1" =
1" =
1" =
1" =
10'
20'
30'
50'
60'
100'
Metric Scale
• Any scale is a multiple of ten
• Any reductions or enlargements are easy
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to perform
No mathematical calculations should be
required
Civil Engineer’s Scale
Divisions
Ratio
Scales Used with This Division
10
1:1
1" = 1"
1" = 1'
1" = 10'
1" = 100'
20
1:2
1" = 2"
1" = 2'
1" = 20'
1" = 200'
30
1:3
1" = 3"
1" = 3'
1" = 30'
1" = 300'
40
1:4
1" = 4"
1" = 4'
1" = 40'
1" = 400'
50
1:5
1" = 5"
1" = 5'
1" = 50'
1" = 500'
60
1:6
1" = 6"
1" = 6'
1" = 60'
1" = 600"
Civil Engineer’s Scale
• Any multiple of ten
• 10 scale often used for mechanical
drawings at full, decimal-inch scale (1:1)
• 20 scale common for mechanical drawings
at half scale (1:2)
• 20 scale used for scales of 1" = 2', 1" = 20',
and 1" = 200'
• 50 scale popular in civil drafting
Architect’s Scale
• 11 different scales
• Ten of the scales
 Inch
represents a specific increment of feet
 Feet subdivided into multiples of 12 parts to
represent inches and fractions of an inch
• Eleventh scale
 Full
scale divided into 16 parts, each part
equal to 1/16 of an inch
Mechanical Engineer’s Scale
• Common for mechanical drawings in
fractional or decimal inches
• Full-scale divisions divided into 1/16,
10, and 50
Vellum
• Most common drafting media
• Inexpensive
• Good smoothness, erasability, and
transparency
• Less durable and dimensionally stable
• Appropriate for regular graphite leads
• Well drawn graphite on vellum
reproduces well
Polyester Film
• Mylar®
• Expensive
• Excellent durability, smoothness,
erasability, dimensional stability, and
transparency
• Best with ink or special polyester leads
• Well drawn ink on polyester film
reproduces the best
Sheet Size and Format
• Standards for sheet size and format
• ASME Y14.1, Decimal Inch Drawing Sheet
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Size and Format
ASME Y14.1M, Metric Drawing Sheet Size
and Format
Architectural, civil and structural
drawings often use unique sheet format
and may use unique sheet sizes
ASME Inch Sheet Size and Format
[Insert Figure 2.31]
ASME Metric Sheet Size and
Format
Selecting a Sheet Size
• Size of objects drawn
• Drawing scale
• Amount of additional content on the
sheet
• Border
• Title block
• Drafting standards and company
practice
ASME Inch Sheet Sizes
Size Designation
Size in Inches
Vertical
Horizontal
8 1/2
11 (horizontal format)
11
8 1/2 (vertical format)
B
11
17
C
17
22
D
22
34
E
34
44
F
28
40
A
G, H, J, and K apply to specific roll sizes
ASME Metric Sheet Sizes
Size in Millimeters
Size Designation
Vertical
Horizontal
A0
841
1189
A1
594
841
A2
420
594
A3
297
420
A4
210
297
A1.0, A2.1, A2.0, A3.2, A3.1, and A3.0 apply to specific elongated sizes
Line Format
• Specified in ASME Y14.2M, Line
Conventions and Lettering
• Thick lines of 0.6 mm (.02 in.)
• Borders
• Outline of principle blocks
• Main divisions of blocks
• Thin lines of 0.3 mm (.01 in.)
• Dividing parts lists and Revision History blocks
• Minor subdivisions of the title block and
supplementary blocks
ASME Lettering Style
• Vertical uppercase Gothic
• Arial, Roman, or similar font when
using CADD
ASME Letter Heights
Sheet Elements
Minimum Letter
Letter Heights Drawing Sizes
Drawing Sizes INCH
Heights INCH
METRIC (mm)
METRIC
Drawing title, sheet size,
CAGE Code, drawing
number, revision letter in
the title block
.24
D, E, F, H, J, K
6
A0, A1
Drawing title, sheet size,
CAGE Code, drawing
number, revision letter in
the title block
.12
A, B, C, G
3
A2, A3, A4
Zone letters and numbers
in borders
.24
All sizes
6
All sizes
Drawing block headings
All other characters
.10
.12
All sizes
All sizes
2.5
3
All sizes
All sizes
Border
• Format margin of a sheet
• Borderlines form a rectangle to
establish the border
• ASME minimum distance from the
edges of the sheet to borderlines:
• .5 in. for all inch drawing sheet sizes
• 20 mm for A0- and A1-size sheets
• 10 mm for A2-, A3-, and A4-size sheets
Zoning
• Allows the drawing to read like a road
map
• Recommend by ASME standards for all
sheets
• Optional for A, B, and A4 size sheets
Title Block
• Provides a variety of
information about a
drawing
• Size and location
specified by ASME
standards
• Other sheet blocks
often group with the
title block
ASME Title Block
1. Company or design
activity
2. Title
3. Sheet size
4. CAGE Code
5. Drawing number
6. Revision of the part
or drawing
7. Principal drawing
scale
8. Actual or estimated
weight
9. Sheet relative to a
group of sheets or
set of sheets
10.Approvals 1
11.Approval 2
12.Approval 3
Angle of Projection Block
• Third angle projection
• First angle projection
Dimensioning and Tolerancing
Block
Revision History Block
1. Zone
2. Revision
3. Description
4. Date
5. Approval
Revision Status of Sheets Block
• Not required on single-sheet drawings
• Horizontal or vertical
• Located by the title block or in the
area of the Revision History block
Revision Status Notation
• ALL SHEETS ARE THE SAME REVISION
STATUS
• Optional
• Next to the title block when the
revision status of all sheets is the same
Additional Sheet Blocks and
Symbols
• Margin drawing number block
• Application block
• Microfilm alignment arrows
Diazo Reproduction
• Ozalid dry prints or blue-line prints
• Not an actual blueprint
• Mostly replaced by photocopy
reproduction and CADD prints
Photocopy Reproduction
• Photocopy printers or engineering
copiers
• Photographically reproduces material,
especially by xerography
• Advantages over diazo printing
Properly Folding Prints