4
Basic Drafting Techniques
Section 4.1
Getting Ready to Draw
Section 4.2
Creating a Drawing
Chapter Objectives
• Prepare a drawing
•
•
•
•
sheet for a technical
drawing.
Use basic drafting
tools and equipment.
Produce a finished
technical drawing
using board-drafting
techniques.
Use standard layouts
to create and set up a
drawing file on a CAD
system.
Create basic geometry
and produce a technical drawing using CAD
commands.
Checkmate Each type of piece
you need for a chess game must
go through an entire design
process. How many pieces would
you need to design for a complete
chess set?
88
Todd France/Corbis
Drafting Career
Michael Graves, Product Designer
When you think of a chess set, do you think of
mechanical drawing and illustrations? Michael Graves
and his team of designers understand the connection.
Graves is a world-renowned architect and designer
who creates the whimsically designed games, dog
food dishes, toasters, teapots, and housewares that are
sold in Target stores nationwide.
The Graves design team uses CAD software to
visualize and design each product. The team presents
paper drawings with just a few models. Then 3D
drawings are completed and used to manufacture the
large assembly machines that stamp out the forms or
create the molds for items like toasters and cappuccino makers.
Academic Skills and Abilities
• Math
• Computer science
• Information systems
• Computer programming
• Business management skills
• Verbal and written communication skills
• Organizing and planning skills
Career Pathways
In addition to a bachelor’s degree in industrial
design, commercial and industrial designers usually receive on-the-job training and normally need
one to three years of training before they advance to
higher level positions. Some experienced designers
open their own design firms.
Go to glencoe.com for this book’s OLC to learn more
about Michael Graves Design.
89
4.1
Getting Ready to Draw
Connect Board and CAD drafters must select and gather the appropriate tools and prepare
their work areas. As you read this section, take notes on preparing a drawing sheet.
Content Vocabulary
• sheet layout
• reference
zones
• revision
• drawing
history block
• application
blocks
templates
• model space
• paper space
• limits
• layer
Academic Vocabulary
Learning these words while you read this section will also help you in your other subjects and tests.
• appropriate
Graphic Organizer
On a chart like the one below, list the tools you will need to create a board-based drawing and a
CAD drawing.
Board-Based Drafting tools
CAD tools
Go to glencoe.com for this
book’s OLC for a downloadable
version of this graphic organizer
Academic Standards
English Language Arts
Use written language to communicate effectively (NCTE 4)
Conduct research and gather, evaluate, and synthesize data to communicate discoveries (NCTE 7)
Mathematics
Number and Operations Compute fluently and make reasonable estimates (NCTM)
Problem Solving Solve problems that arise in mathematics and other contexts (NCTM)
NCTE National Council of
Teachers of English
NCTM National Council
of Teachers of
Mathematics
ADDA American Design
Drafting Association
ANSI
American National
Standards Institute
ASME American Society of
Mechanical Engineers
Industry Standards
ADDA Section 1
Functional/Simplified Drafting (ASME Y14.3M, ANSI Y14.4, ANSI Y14.6)
90
Chapter 4 Basic Drafting Techniques
Ted Mishima
Preparing the Drawing
Sheet
What are the steps in preparing a drawing
sheet?
Hold Head of
T-Square in
contact with
edge of
board
Align edge
of paper
with blade of
T-Square
Proper sheet preparation is an important part of the drafting process. Preparing the drawing sheet includes choosing an
appropriate size and type of drawing sheet,
fastening it to the drawing board, and laying
out the borders and title block.
Choosing the Drawing Sheet
Approx. 1”
The type of drawing sheet you select
depends on how the final drawing will be
used. For example, drawing paper is appropriate for short-term use, while polyester film is
better for long-term use.
The size of the sheet is determined by the
size and complexity of the drawing. It is often
useful to make a freehand sketch of the views
and notes before proceeding to do the final
instrument drawing. Except in rare cases,
standard drawing-sheet sizes should be used.
Fastening the Drawing Sheet to
the Board
By attaching the drawing sheet to the
board, you have the freedom to move the Tsquare and triangles freely over the whole
sheet. The sheet may be held in place on the
board in several ways. Some drafters put drafting tape across the corners of the sheet and,
if needed, at other places. Others use small,
precut, circular pieces of tape, called dot tape.
Neither of these two methods will damage the
corners or the edges of the sheet. They also
can be used on composition boards or other
boards with hard surfaces.
To fasten the paper or other drawing sheet,
place it on the drawing board with the left
edge 1″ (25 mm) or so away from the left edge
of the board, as shown in Figure 4-1. (Lefthanded students should work from the right
edge.) Put the lower edge of the sheet at least
4″ (100 mm) up from the bottom of the board
so you can work on it comfortably. Then
line up the sheet with the T-square blade, as
shown in Figure 4-1. Hold the sheet in position. Move the T-square down, keeping the
Figure 4-1
To fasten the drawing sheet to the board, first
align the sheet with the T-square blade.
head of the T-square against the edge of the
board. Then fasten each corner of the sheet
with drafting tape.
Sheet Layout
Sheet Layout is the process of placing the
border and title block on the drawing sheet.
U.S. Customary drawing sheet layouts (inch
sizes) are designed and recommended by the
American Society of Mechanical Engineers
(ASME). Metric sheet layouts (millimeter
sizes) are designed and recommended by the
International Organization for Standardization (ISO). Margins for the borders on metric
sheets are somewhat uniform in size, while
those on U.S. Customary sheets vary. However, the sheet sizes and layouts prepared
by ASME and ISO are simply recommendations. They may vary according to the user’s
Section 4.1 Getting Ready to Draw
91
requirements. However, all drawing sheets
should have a border and title block. Also, it
is strongly recommended that the location of
various elements of the title block be placed
as specified by ASME or ISO. In many industries, borders and title blocks are printed on
the drawing sheets and the drafter simply fills
in the blanks in the title block and prepares
the drawing within the borderlines.
The layout recommendations of both ASME
and ISO are shown in Figure 4-2. ASME actually lists six standard sizes for drawing sheets
plus special roll sizes, and ISO lists five standard sizes plus various elongated sizes. The
information in Figure 4-2 is limited to the
most common sheet sizes used in educational
programs.
Reference zones given in the margins
are used to locate specific information on
the drawing. The title block provides basic
information about the drawing— the “who,
what, when, and where.” The revision
history block specifies revision dates and
related information. The application
blocks are optional. They provide columns
for purposes such as listing specific information used to relate a given drawing to other
drawings in a set.
Identify What do the acronyms ASME and
ISO stand for?
Sheet Layout: U.S. Customary
Table 4-1 gives specific sizes for standard
sheets. For example, an A-size sheet placed
in the horizontal position is 8.50 vertically
and 11.00 horizontally (8.50 11.00). When
placed in the vertical position, it is 11.00 vertically and 8.50 horizontally (11.00 8.50).
MARGIN DRAWING
NUMBER BLOCK
I
A AND A4 SIZE
(HORIZONTAL)
REFERENCE ZONES
D
2
REVISION
HISTORY
BLOCK
APPLICATION BLOCK
I
F
REVISION
HISTORY BLOCK
C
SEE TABLE 4-1
E
B AND A3 SIZE
B
A AND A4 SIZE
(VERTICAL)
B
TITLE BLOCK
D
C AND A2 SIZE
APPLICATION
BLOCK
A
A
6
5
4
3
2
I
TITLE BLOCK
MICROFILM CENTERING ARROW
B
TITLE BLOCK
REVISION STATUS
A
A
8
7
6
5
4
3
2
GENERAL NOTE:
DIMENSIONS SHOWN ARE RECOMMENDED AND MAY BE VARIED
TO ACCOMMODATETHE USER'S REQUIREMENTS.
Figure 4-2
Decimal-inch and metric drawing sheet layout.
92
Chapter 4 Basic Drafting Techniques
I
TITLE BLOCK
Table 4-1
Decimal-Inch Sizes
Margin Sizes
Size
Designation
Vertical
Sheet Size
Horizontal
Sheet Size
A (Horizontal)
8.50
11.00
.38
.25
A (Vertical)
11.00
8.50
.25
.38
B (Horizontal)
11.00
17.00
.38
.62
C (Horizontal)
17.00
22.00
.75
.50
Horizontal
Decimal-Inch and Metric
Drawing Sheets
Vertical
Metric Sizes
A4 (Horizontal)
210 mm
297 mm
10
10
A4 (Vertical)
297 mm
210 mm
10
10
A3
297 mm
420 mm
10
10
A2
420 mm
594 mm
10
10
B- and C-size sheets are generally not used in
the vertical position.
Figure 4-3 shows a recommended layout for the title block, which should be
placed in the lower right-hand corner
of the drawing. Since it is only recommended, it can be altered in both size and
content. For example, “cage code” is a reference number generally used on drawings
prepared for government contracts. It can
be eliminated on drawings that are not
government-related.
Since the trim sizes recommended by
ASME and ISO are in almost universal use in
industry, they are also useful sizes for drafting courses. Most of the drawing problems
throughout this book are planned for A-, B-,
A4-, or A3-size sheets. However, to reduce the
amount of time and space required to draw
the title blocks, you may use the modified
3.90
2.80
.40
INFORMATION RELATED
TO PREPARATION OF
DRAWING INCLUDES
NAME OF DRAFTER,
ENGINEER, CHECKER,
ISSUE DATE, ETC.
COMPANY NAME
AND ADDRESS
TITLE
2.00
1.40
SIZE
CAGE CODE
DWG NO.
REV
.60
SCALE
SHEET
.30
1.80
3.30
4.30
6.30
GENERAL NOTE:
DIMENSIONS SHOWN ARE RECOMMENDED AND MAY BE VARIED
TO ACCOMMODATETHE USER'S REQUIREMENTS.
Figure 4-3
Recommended title block for A, B, and C drawing sheet sized (decimal inch)
Section 4.1 Getting Ready to Draw
93
Larger sheets are generally used only in the
horizontal position.
Figure 4-6 shows a recommended layout for
the metric title block. It is essentially the same
as the decimal-inch title block. The difference is
in the units of measure used to lay it out. Like
the U.S. Customary recommendations, metric
recommendations may be altered to accommodate the user’s specific requirements.
Figures 4-7 and 4-8 show recommended
A4 and A3 drawing-sheet layouts with borders
and title blocks. These have been modified from
the recommended ISO standard metric sheet
version shown in Figure 4-4 for U.S. Customary drawings. Alternate layouts are shown
in Figure 4-5. Your instructor may assign one
of these or one that he or she has designed.
Sheet Layout: Metric
In Table 4-1, you will see that the smallest
metric-size sheet is A4. Placed in a horizontal position, it is 210 mm vertically and 297
mm horizontally (210 297). When placed
in a vertical position, it is 297 mm vertically
and 210 mm horizontally (297 210). The
A4-size sheet may be used in either position.
.50
8.50
OR
17.00
5 X .12
NAME OF SCHOOL
LOCATION
DRAWING NAME
SCALE
DRAWN BY
DATE
DWG NO.
.60
APPROVED BY
.30
3.00
3.00
.80
.30
11.00
Figure 4-4
Suggested sheet layout for an A- or B-size sheet.
B ( 11x17 ) or A3
( 297 mm x 420 mm )
Drawing Sheet
Horizontal Position
B ( 11x17 ) or A3
( 297 mm x 420 mm )
Drawing Sheet
Vertical Position
Figure 4-5
Alternate layouts.
A ( 8.50 x 11.00 ) or A4
( 210 mm x 297 mm )
Drawing Sheet
Horizontal Position
94
Chapter 4 Basic Drafting Techniques
layouts. The sheet sizes are ISO standard; the
layouts have been modified to save time and
space in preparing the sheets. Your instructor
may assign one of these or one that he or she
has designed. Figure 4-8 shows alternate title
block layouts for decimal-inch and metric drawing sheets.
Identify Where is the title block placed on a
drawing?
95
70
10
COMPANY NAME
AND ADDRESS
INFORMATION RELATED
TO PREPARATION OF
DRAWING INCLUDES
NAME OF DRAFTER,
ENGINEER, CHECKER,
ISSUE DATE, ETC.
TITLE
54
36
SIZE
CAGE CODE
DWG NO.
REV
16
SCALE
SHEET
6
45
80
Figure 4-6
110
Recommended title
block for A2, A3, and
A4 drawing-sheet sizes
(metric)
160
12
210
METRIC
NAME OF SCHOOL
LOCATION
Recommended sheet
layout for an A4- or
A3-size sheet
5X3
DRAWING NAME
SCALE
DRAWN BY
DATE
DWG NO.
15
APPROVED BY
Figure 4-7
8
75
8
20
75
8
297
METRIC
Decimal-inch
.12 TYPICAL
3mm TYPICAL
NAME OF SCHOOL
DRAWING NAME
SCALE
DRAWING NAME
2.10
DWG NO.
.60
APP BY
15
LOCATION
.60
DATE
DWN BY
Figure 4-8
NAME OF SCHOOL
.60
LOCATION
SCALE
15
53
DATE
DWN BY
DWG NO.
15
Alternate title block
layouts for decimal-inch
(A- and B-size) and metric
(A3- and A-4 size) sheets
APP BY
.30
.80
3.30
8
20
.30
.30
85
Section 4.1 Getting Ready to Draw
95
Getting Ready to Create
a CAD Drawing
How does preparing a CAD drawing differ
from preparing a drawing sheet?
Techniques for creating a technical drawing
using CAD differ greatly from those used in
board drafting. One of the biggest differences
is that CAD drawings are drawn at full scale,
whether the object being drawn is a microchip or a municipal parking lot.
Obviously, you cannot print a drawing of
a parking lot at full size. Therefore, you must
print the drawing at a scale that allows it to
fit on the selected drawing sheet. If you set
the drawing up properly before you begin to
draw, you can draw at full size and print at the
appropriate scale on the drawing sheet.
In other ways, drafting using a CAD system
is similar to board drafting. You must understand drafting concepts before you can create an acceptable CAD drawing. Except where
noted, all of the drafting principles discussed
in this and other chapters apply equally to
CAD and board drafting.
This part of the chapter is designed to be
“done,” rather than just read. Ideally, you
should have access to a CAD workstation, so
you can try the techniques as you read about
them. If this is not possible, read the contents
thoroughly, and then have the book with you
the next time you have access to CAD.
Creating a New Drawing
As with board drafting, you must plan carefully before you begin to draw in CAD. Even
though you will be drawing at full size, you
must select a sheet size—and a scale—for the
printed drawing before you begin.
The first step in preparing a drawing file is to
open a new drawing in AutoCAD. Some versions
of AutoCAD contain drawing templates for
the various ASME sheet sizes (see Figure 4-9).
A drawing template is a standard drawing setup
that conforms to ASME or ISO standards. For
this example, we will use AutoCAD’s acad.dwt
template.
1. Enter the NEW command to create a
new drawing. For this exercise, either
type NEW or pick New from the File pulldown menu. (Do not use the button on
the Standard toolbar.)
2. In the Select Template dialog box, select
the acad.dwt template.
Notice the MODEL button at the bottom of
the screen, below the border and title block.
AutoCAD has two drawing spaces. Model
space is a working space, where you will
do most of your drawing. Layout, or paper
space, allows you to position your drawing
on the specified drawing sheet.
In most versions of AutoCAD, you will also
see tabs at the bottom of the drawing area. If
the tabs are not present, right-click the Model
or Paper button on the status bar and choose
REVISIONS
ZONE
REV
DESCRIPTION
DATE
APPROVED
Figure 4-9
Some versions of AutoCAD
provide templates for
standard ISO and ASME
borders and title blocks.
This is a layout for a B-size
sheet.
SIZE
SCALE
96
Chapter 4 Basic Drafting Techniques
FSCM NO.
DWG NO.
REV
SHEET
to show the Model and Layout tabs. Remember to choose the Model tab whenever you are
actually creating or editing a drawing. Choose
the appropriate layout tab to view or work
with the drawing in paper space.
Setting the Drawing Units
Drawings based on the acad.dwt template
open automatically in model space. Be sure
that the Model tab is the active tab. Then continue to set up the drawing file. The next task
is to specify the drawing units.
In AutoCAD, the term unit is purposely
vague. AutoCAD ensures that 1 unit 1 unit.
It is up to you to determine whether the unit
stands for millimeters, inches, miles, or, for
some engineering applications, even hours or
other nonlinear units. Therefore, before you
begin drawing, you must specify what the
units will be.
To set the units in a drawing, enter the
UNITS command. AutoCAD presents a dialog
box that lets you choose from architectural,
decimal, engineering, fractional, or scientific
units for both length and angle measurements. For the drawings in this textbook, you
should choose decimal units unless directed
otherwise.
Selecting decimal units in AutoCAD does
not limit you to working in decimal inches.
By choosing decimal units, you are setting
up the drawing correctly for both ASME and
ISO standards. Only the precision differs. For
ASME, select a length precision of two decimal places (0.00). For ISO or metric, select a
length precision of one decimal place (0.0).
For both standards, set angle precision to no
decimal places (0), unless directed otherwise.
In this case, choose precisions.
Setting the Drawing Limits
Next, set the limits, or physical size of
the drawing area, to correspond to the drawing sheet size you will use for paper space.
The paper-space layout does not affect
model space, so you have to set the limits
separately.
Zooming
CAD programs allow you to “zoom
out” to see all of a drawing, or “zoom
in” to see part of it in a magnified
form that is easier to see and work
with. After you have set the drawing limits and set the snap and grid,
zoom out to see the whole drawing.
To do so, enter the ZOOM command
(or press the “z” key and Enter) and
then type the word All. The entire
drawing space appears in the drawing area.
Later, if you want to see a detail of
part of the drawing, enter the ZOOM
command and then specify the part
you want to see by using the mouse
to create a window, or rectangle,
around that part. ZOOM All always
takes you back to a view of the entire
drawing.
17 11. To do this, use the LIMITS command. This command works by specifying
the lower left and upper right corners of the
drawing area.
Enter the LIMITS command, and then look
at the Command line at the lower left corner
of the screen. It shows that the lower left corner is currently set to 0.00,0.00. This means
that the lower left corner of the drawing is
set at 0.00 inches horizontally and vertically.
In general, you should leave the values at
0.00,0.00. Press Enter to continue. For an Asize sheet (without scaling), type 11.00,8.50
and press Enter. Do not type a space between
the comma and the 8.50. Then enter the
ZOOM command and the All option to view
the entire drawing area.
Limits for Printing at Full Size
This example will use an A-size sheet. If
your drawing will fit on the sheet without
scaling, you should set the drawing size to
Describe What function does the LIMITS
command perform?
Section 4.1 Getting Ready to Draw
97
Sheet Size
Drawing
Scale
ASME A
1:1
1:2
1:4
11.00 8.50
22.00 17.00
44.00 34.00
ASME B
1:1
1:2
1:4
17.00 11.00
34.00 22.00
68.00 44.00
ASME C
1:1
1:2
1:4
17.00 22.00
34.00 44.00
68.00 88.00
1:1
1:2
1:4
210 mm 297 mm
420 mm 594 mm
840 mm 1188 mm
ISO A3
1:1
1:2
1:4
297 mm 420 mm
594 mm 840 mm
1188 mm 1680 mm
ISO A2
1:1
1:2
1:4
420 mm 594 mm
840 mm 1188 mm
1680 mm 2376 mm
ISO A4
Ø.50
10 – 32 UNC – 2B
ASME B1.1
Model Space
Limits
.50
Ø2.00
Ø1.10
R.10
.20
1.50
.05 X 45°
CHAMFER
A
Table 4-2
Drawing limits
B
Figure 4-10
Limits for Printing a Scaled
Drawing
If you plan to scale the drawing to fit on the
drawing sheet, you should set the model space
limits accordingly. For example, suppose you
are working with a B-size sheet, and you plan
to print the drawing at a scale of 1:2. In other
words, your full-size drawing will be twice
as big as it will appear on the printed sheet.
Therefore, your model-space limits should be
twice the size of the B-size sheet, or 34 22.
Table 4-2 shows common drawing limits for
drawings of different sizes and scales.
Working with Layers
All CAD programs, including AutoCAD,
have a system of layers that gives the CAD
operator much greater control over a drawing. A layer is similar to a transparent paper
overlay. By setting up a layer for dimensions,
for example, the CAD operator can control
whether dimensions are displayed by turning the layer on and off, or by “freezing” and
“thawing” it, as shown in Figure 4-10.
Most companies have rules about what layers to use, what to call them, and what colors
98
Chapter 4 Basic Drafting Techniques
By placing dimensions on a separate layer, you
can control whether the dimensions display. In
(A), the dimension layer is displayed. In (B), it has
been frozen, so it does not show on the screen. If
you print the drawing with the dimension layer
frozen, the layer will not print.
should be associated with them. Some companies even use their own drawing templates
in which these layers have already been set
up. For instructional purposes, this textbook
will use a generic set of layers. These layers are
shown in Table 4-3.
Creating a New Layer
To set up new layers in a drawing, enter the
LAYER command. Look closely at the contents
of the dialog box. The 0 layer is the default
layer. Notice that several properties are listed
for each layer, including:
•
•
•
•
•
layer name
on or off
frozen or thawed
layer color
linetype
• line weight
• plot style
• plot (whether the layer plots when the
drawing is printed)
Some versions of AutoCAD have additional properties, but those listed here are
common to all versions. One of the standard
layers used in this textbook is the Objects
layer. This layer will be used for all of the visible lines of the part or object. Therefore, you
already know that it will need to be a solid
(or continuous) line that is .30 mm thick. To
create a new layer named Objects, click the
New button in the dialog box. A new layer
appears in the window, and the layer name
is highlighted. Type the word Objects in the
layer name box.
Setting the Layer Color
Figure 4-11
By default, new layers in AutoCAD are
white. To set the color for a layer, pick White
or the color box for that layer. A color palette
appears. To choose a different color, just pick
a color and pick OK. However, because this is
the Objects layer, leave it white.
Colors are used in CAD programs to help
the CAD operator distinguish among the
layers. See Figure 4-11. Some companies
prefer to use white for all of their layers. Others establish company-wide standards. For
example, they may declare that all electrical
wiring will be on a blue layer named Electr.
These colors may or may not print, depending on the plot setting and the printer being
used. It is also possible to set up the layers in
Colors can be used to distinguish visually the
different elements in a CAD file.
Name
Color
Linetype
Line Weight
Objects
White
Continuous
.30 mm
Dimensions
Red
Continuous
.18 mm
Hidden Lines
White
Hidden
.18 mm
Centerlines
Blue
Center
.18 mm
Notes
Magenta
Continuous
.18 mm
Border
White
Continuous
.18 mm
Viewports
Magenta
Continuous
.18 mm
Table 4-3
Layers for drafting problems
various colors, but set up a plot style to print
them all in black ink. Therefore, the color of
a layer may or may not determine the color
of the lines on that layer when the drawing is
printed. This is up to the individual drafter or
company.
Selecting the Linetype
AutoCAD gives new layers a continuous linetype by default, so the Objects
layer is already set up for the correct linetype. However, as you can see in Table 4-3,
you will need to change it for some of the
other layers. To do so, click the word Continuous. A dialog box appears from which
you can change the linetype, but notice
that you have no other choices. To load
other standard linetypes into the drawing,
pick the Load button. Another dialog box
appears, allowing you to select from several
ISO and ASME linetypes. To load the ISO
standard dashed line, for example, choose
ISO02W100 ISO Dash and pick OK. The linetype becomes available for use in the drawing. To choose the ASME standard dashed
line for hidden lines, scroll down to Hidden,
pick it, and pick OK.
Section 4.1 Getting Ready to Draw
99
Figure 4-12
AutoCAD provides
many standard line
widths.
Selecting the Line Width
The default line width in AutoCAD is 0.
This does not mean that the line does not
print. However, the width of the line is not
defined. You can and should define the width
of the lines on your drawings. To do so, pick
the word Default in the Line Width column
for the Objects layer.
AutoCAD specifies all of its line widths in
millimeters, as shown in Figure 4-12. Visible
lines in CAD are generally made at a width of
.12, or .30 mm. Select .30 mm from the list
of line widths, and pick OK to apply it to the
Objects layer.
Section 4.1 Assessment
After You Read
Self-Check
1. Describe the procedure for preparing a
drawing sheet for a technical drawing.
Academic Integration
English Language Arts
2. Write a one-page essay explaining
the different parts of a sheet layout.
Use Content Vocabulary terms and
other information from this section to
explain each part of the layout.
Loading Linetypes
You will usually know in advance
which linetypes you will need for a
drawing. It is more efficient to load
all of the needed lines at one time,
before you close the dialog box. After
adding each linetype, pick the Load
button again to choose another one.
Some versions of AutoCAD allow you
to load all available linetypes by picking a Load All button. When you have
finished, select the linetype you need
for the current layer. Then, select
OK to return to the dialog box for
managing layers.
Finishing Layer Setup
Now finish the layer setup for your drawing by creating the other layers listed in Table
4-3. Be sure to give each layer the properties
shown in the table. Then enter the Save command to save the drawing file. Because of the
settings chosen in this example, a suitable
name for this file in Chapter 4 ASME B Full
Scale, or use a name given by your instructor.
Drafting Practice
3. On an 8½ 11 inch sheet of grid paper
(inch or metric), sketch the borders
and title block shown in Figure 4-6 or
4-9 as assigned by your instructor. All
guidelines for lettering should be very
thin and light; all other lines should be
thick, sharp, and black.
4. If you have access to a computer with
CAD software, follow the procedure you
just read about to set up an ASME B-size
drawing sheet that includes borders and
title block. Experiment with other sheet
sizes. What are the dimensions of a
B-size sheet?
Go to glencoe.com for this book’s OLC
for help with this drafting practice.
100
Chapter 4 Basic Drafting Techniques
4.2
Creating a Drawing
Preview When preparing to draw, it is important to know how to use the basic tools. As you read
this section, have your drawing tools or computers ready, so you can practice the various techniques.
Content Vocabulary
• inking
• alphabet of lines
• inclined lines
• hidden lines
• centerlines
• line weight
• symmetrical
• Ortho mode
• polar
• polyline
• radius
• snap
• grid
• viewports
coordinates
Academic Vocabulary
Learning this word while you read this section will also help you in your other subjects and tests.
• differentiate
Graphic Organizer
On a chart like the one below, list the basic ASME and ISO standards you will need to follow when
drafting in CAD.
ASME Standards
ISO Standards
Go to glencoe.com for this
book’s OLC for a downloadable
version of this graphic organizer
Academic Standards
NCTE National Council of
Teachers of English
Science
Science and technology in local, national, and global challenges (NSES)
NCTM National Council
of Teachers of
Mathematics
Mathematics
Geometry Use visualization, spatial reasoning, and geometric modeling to solve problems (NCTM)
English Language Arts
Read texts to acquire new information. (NCTE)
Industry Standards
NSES National Science
Education Standards
ADDA American Design
Drafting Association
ANSI
American National
Standards Institute
ASME American Society of
Mechanical Engineers
ADDA Section 1
Functional/Simplified Drafting (ASME Y14.3M, ANSI Y14.4, ANSI Y14.6)
Section 4.2 Creating a Drawing
101
When using drawing tools, why is it
important to keep the drawing neat
and clean?
Techniques for using drafting pencils are
somewhat different from those for using technical pens. Unlike pencil marks, ink must be
allowed to dry before it can be touched. This
affects the way the instrument should be held,
as well as the order in which the lines should
be drawn.
Sharpening the Pencil
grade mark, being careful not to cut the lead.
Leave about half an inch (13 mm) exposed.
Then shape the lead to a long, conical point.
Do this by rubbing the lead back and forth on
a sandpaper pad or on a long file, while turning it slowly to form the point, as shown in
Figure 4-13B and 4-13C. Some drafters prefer the flat point, or chisel point, shown in
Figure 4-13D. Keep the sandpaper pad or file
at hand, so that you can sharpen the point
often, as shown in Figure 4-14.
Mechanical sharpeners have special drafter’s
cutters that remove the wood, as shown in
Figure 4-15. Special pointers are made for
shaping the lead, as in Figure 4-16. Such
To sharpen a wooden pencil, cut away the
wood at a long slope, as shown in Figure
4-13A. Always sharpen the end opposite the
A
B
C
D
Figure 4-13
Figure 4-15
Sharpening the pencil properly is important.
A drafter’s pencil sharpener cuts the wood,
not the lead.
Figure 4-14
Rub the pencil
on a sandpaper
pad, turning
it slowly, to
achieve a
conical point.
BEFORE
AFTER
Figure 4-16
The lead pointer allows a choice of point shapes.
102
Chapter 4 Basic Drafting Techniques
Ted Mishima
Working with Drafting
Pencils and Pens
Courtesy of Staedtler Inc.
uniform and keep the point from wearing
down unevenly.
Inking Techniques
Inking is the process of creating technical drawings using technical pens. Techniques
for inking are slightly different from those
for drawing in pencil. Hand position and the
order in which items are drawn are affected
by the fact that ink, unlike pencil, must be
allowed to dry to help avoid smudges.
Figure 4-17 shows the correct position
for drawing lines with a technical pen. Hold
the technical pen in a nearly vertical position,
perpendicular to the drawing surface, to get
the most uniform line.
Using Erasers
Figure 4-17
The position of the technical pen is important
when drawing lines.
devices may be hand-operated or electrically
powered.
Mechanical pencils hold plain sticks of lead
in a chuck that allows the exposed lead to be
extended various lengths. The lead for most
lead holders should be shaped in the same
way as the lead in wooden pencils. Some refill
pencils have a built-in sharpener that shapes
the lead.
Never sharpen a pencil over the drawing
board. After you sharpen a pencil, wipe the lead
with a cloth or a Styrofoam™-type “stab-it” to
remove the dust. Being careful in these ways
will help keep the drawing clean and bright.
Techniques for Using a Drafting
Pencil
Pencil lines must be clean and sharp; not
fuzzy. They must be dark enough for the views
to be seen when standard line widths are used.
If you use too much pressure, you will groove
the drawing surface. You can avoid this by
using the correct grade of lead.
Rotate the pencil between your thumb and
forefinger as you draw to help make the line
Use soft erasers to clean soiled spots or light
pencil marks from drawings. Keep in mind
that regular ink erasers often contain grit.
If you use these erasers at all, use them very
carefully to keep from damaging the drawing
surface.
The ink used on polyester drafting film is
waterproof. However, you can easily remove
ink from the film by rubbing it with a moistened plastic eraser or by using an electric erasing machine. Do not apply pressure when
rubbing. The polyester film does not absorb
ink, so all ink dries on top of its highly finished surface. Remove ink from other surfaces,
such as tracing vellum or illustration board,
with regular ink erasers or chemically treated
ink erasers that absorb ink. Press lightly with
strokes in the direction of the line to remove
ink caked on the surface. Too much pressure
damages the surface and makes it hard to
revise the drawing.
When working on paper or cloth, erase
lines along the direction of the work. On film,
always erase across the direction of the work.
Always erase carefully to avoid marring the
finish on the drawing sheet. Use an erasing
shield to protect nearby lines and areas that
you do not want to erase.
Contrast Explain how using a drafting
pencil differs from using a drafting pen.
Section 4.2 Creating a Drawing
103
THICK
THICKNESS MAY VARY
TO SUIT SIZE OF
DRAWING
THIN
DASHES .12±
SPACES .03±
THIN
EVENLY SPACED
ON SECTION VIEW
VISIBLE LINE
HIDDEN LINE
VISIBLE LINE
HIDDEN LINE
CENTERLINE
SECTION LINE
THIN
CENTERLINE
LONG DASHES
.75 TO 1.50±;
SHORT DASHES .06±
SECTION LINE
CUTTING-PLANE LINE
EXTENSION LINE
EXTENSION LINE
EXTENDS BEYOND
DIMENSION LINE .12±
HIN
T
LEADER
THIN
Ø.375
LEADER
DIMENSION LINE
1.62
2.50
2'–3
THIN
THIN
DIMENSION LINE
EXTENSION LINE
DIMENSION LINE
THICK
CUTTING-PLANE LINE OR VIEWING-PLANE LINE
DIMENSION LINE
UNBROKEN EXCEPT AT
FIGURE; ARROWHEADS
AT ENDS
UNBROKEN DIMENSION
LINE WITH FIGURE
ABOVE USED FOR CIVIL
AND ARCHITECTURAL
DRAWINGS
LONG DASHES .75
TO 1.50±; SHORT
DASHES .12±;
SPACES .06±
SHORT-BREAK LINE
THICK
EQUAL DASHES .25±
CUTTING-PLANE LINE OR VIEWING-PLANE LINE
THICK
FREEHAND LINE FOR
SHORT BREAKS
THIN
RULED LINES WITH
FREEHAND ZIGZAGS
FOR LONG BREAKS
THIN
LONG DASHES .75
TO 1.50±; SHORT
DASHES .12±
FOR ALTERNATE
POSITIONS, REPEATED
DETAIL, ETC.
SHORT-BREAK LINE
LONG-BREAK LINE
LONG-BREAK LINE
TRAVEL
PHANTOM LINE
PHANTOM LINE
Figure 4-18
Alphabet of lines
104
Chapter 4 Basic Drafting Techniques
Ted Mishima
Alphabet of Lines
Why is the term “alphabet” used to
describe the various lines used in drafting?
The different lines or line symbols used
on drawings form a kind of graphic alphabet
commonly known as the alphabet of lines.
The line symbols recommended by ASME are
shown in Figure 4-18. Two line widths–thick
and thin—are generally used. Drawings are
easier to read when there is good contrast
among different line widths. All lines must be
uniformly sharp and black.
other material. Always keep the point of the
lead a little distance away from the corner
between the guiding edge and the drawing
surface, as shown in Figure 4-20. This will
let you see where you are drawing the line.
It will also help you avoid making a poor or
smudged line. Be careful to keep the line parallel to the guiding edge.
Explain Why does the alphabet of lines
utilize two different line widths?
Techniques for Drawing
Lines
Why does line drawing require special
instruments?
The sections that follow discuss basic drawing techniques. Additional, more complex
techniques will be presented in later chapters.
Horizontal Lines
To draw a horizontal line, use the upper
edge of the T-square blade as a guide. With
your left hand, place the head of the T-square
in contact with the left edge of the board.
Keeping the head in contact, move the Tsquare to the place you want to draw the line.
Slide your left hand along the blade to hold
it firmly against the drawing sheet. Hold the
pencil about 1" (25 mm) from its point. Slant
it in the direction in which you are drawing
the line. (This direction should be left to right
for right-handers and right to left for lefthanders.) While drawing the line, rotate the
pencil slowly and slide your little finger along
the blade of the T-square, as shown in Figure
4-19. This will give you more control over the
pencil.
On film, keep the pencil at the same angle
(55° to 65°) all along the line. You must also
use less pressure on film than on paper or
Figure 4-19
Drawing a horizontal line.
GUIDE (T-SQUARE
OR TRIANGLE)
90°
SPACE
TILT PENCIL
SLIGHTLY FOR
EXTREME ACCURACY
60° TO 75°
ON PAPER
OR CLOTH
55° TO 65°
ON FILM
POSITION OF PENCIL
VIEWED FROM THE FRONT
Figure 4-20
To ensure accurate drawing, position the pencil
as shown here.
Section 4.2 Creating a Drawing
105
Use a triangle and a T-square to draw vertical lines, as shown in Figure 4-21. Place the
head of the T-square in contact with the left
edge of the board. Keeping the T-square in
contact, move it to a position below the start
of the vertical line. Place a triangle against the
T-square blade. Move the triangle to where
you want to begin the line. Keeping the vertical edge of the triangle toward the left, draw
upward. Slant the pencil in the direction in
which you are drawing the line. Be sure to
keep this angle the same when you are drawing on film. Keep the point of the lead far
enough out from the guiding edge so you can
see where you are drawing the line. Be careful
to keep the line parallel to the guiding edge.
Figure 4-21
Drawing a vertical line
Inclined Lines
Inclined lines are lines drawn at an
angle that is neither horizontal nor vertical.
Decimal Degrees
It is becoming a more common practice to
specify angles in decimal degrees rather than
degrees, minutes, and seconds. Convert
the following measurements into decimal
degrees.
Decimal Degree Equivalent
Degrees, Minutes
and Seconds
0°45
0°014
25°3036
Decimal Degrees
25°030
Academic Standards
Mathematics
Select, apply, and translate among mathematical
representations to solve problems. (NCTM)
106
Chapter 4 Basic Drafting Techniques
Degrees convert directly to
the same number of decimal degrees. Minutes will be divided by 60 minutes per degree
to arrive at the decimal degree, and seconds
will be divided by 3600 seconds per degree to
arrive at the decimal degree.
Example:
Convert 25°3036 to decimal degrees.
25°
25.00 degrees
30
.50 degrees
(30 minutes / 60 minutes per degree .50)
36 .01 degrees
(36 seconds / 3600 seconds per degree 01)
25.51 degrees
For math help, go to the Math
Appendix located at the back of
this book.
Ted Mishima
Vertical Lines
They are drawn using triangles, a protractor,
or a drafting machine.
30°, 45°, and 60° Lines
Angles are measured in degrees, minutes, and seconds. You can draw lines
at 30°, 45°, or 60° angles from the horizontal or vertical by using the triangles.
Lines inclined at 30° and 60° are drawn
with the 30°-60° triangle held against the
T-square blade, as shown in Figure 4-22
or against a horizontal straightedge. The
30°-60° triangle can also be used to lay off
equal angles, 6 at 60° or 12 at 30°, about a
center point.
To draw lines inclined at 45° from horizontal or vertical lines, hold the triangle
against the T-square blade, as shown in
Figure 4-23, or against a horizontal
straightedge. The 45° triangle can also be
used to lay off eight equal angles of 45°
about a center point.
Lines Inclined at 15° Increments
The 45° and 30-60° triangles, alone or
together and combined with a T-square, can
be used to draw angles increasing by 15° from
the horizontal or vertical line. Some ways of
placing the triangles to draw angles of 15° and
75° are shown in Figure 4-24.
90°
8 ANGLES AT
45° = 360°
45°
90°
90°
90°
A
B
C
Figure 4-23
The 45° triangle has angles of 45° and 90°.
60°
6 ANGLES AT
60° = 360°
15°
15°
60°
75°
75°
75°
75°
15°
15°
15°
15°
75°
75°
75°
A
60°
B
60°
30°
30°
90°
60°
15°
75°
75°
75°
75°
30°
60°
15°
15°
15°
15°
90°
15°
D
15°
30°
30°
75°
15°
C
90°
90°
15°
75°
75°
12 ANGLES AT
30° = 360°
C
D
A
B
Figure 4-22
Figure 4-24
The 30°-60° triangle has angles of 30°, 60°,
and 90°.
Drawing lines at 15° and 75° using the two
triangles
Section 4.2 Creating a Drawing
107
Techniques for Special Lines
and Surfaces
To describe an object fully, you must show
every feature in each view, whether or not it
can ordinarily be seen. You must also include
other lines that are not actually part of the
object to clarify relationships and positions in
the drawing. To reduce confusion, special line
symbols, or linetypes, are used to differentiate
between object lines and lines that have other
special meanings.
Hidden Lines
It is necessary to describe every part of an
object. Therefore, every detail must be represented in each view, whether or not it can be
seen. Both interior and exterior features are
projected in the same way. Parts that cannot be
seen in the views are drawn with hidden lines
that are made up of short dashes, as shown in
Figure 4-25. Notice in Figure 4-25A that
the first dash of a hidden line touches the line
where it starts. If a hidden line is a continuation of a visible line, space is left between the
visible line and the first dash of the hidden line
(see Figure 4-25B). If the hidden lines show
corners, the dashes touch the corners, as shown
in Figure 4-25C.
Dashes for hidden arcs start and end at the tangent points, as shown in Figure 4-26A. When
a hidden arc is tangent to a visible line, leave a
space, as shown in Figure 4-26B. When a hidden line and a visible line project at the same
place, show the visible line. See Figure 4-26C.
When a centerline and a hidden line project at the same place, draw the hidden line, as
shown in Figure 4-27A. When a hidden line
crosses a visible line as in Figure 4-27B, do
not cross the visible line with a dash. When
A
ARCS END AT TANGENT POINT
A
NO SPACE
SPACE
B
SPACE
SPACE
B
NO SPACE
SPACE
C
C
DASHES TOUCH
108
SHOW FULL LINE
Figure 4-25
Figure 4-26
Treatment of hidden lines
Treatment of hidden arcs
Chapter 4 Basic Drafting Techniques
hidden lines cross, the nearest hidden line
has the “right of way.” Draw the nearer hidden line through a space in the farther hidden
line, as in Figure 4-27C.
A
SHOW HIDDEN LINE — NOT C
Centerlines
Centerlines are special lines used to
locate views and dimensions (see the alphabet of lines, Figure 4-18). Primary centerlines,
marked P in Figure 4-28, locate the center on
symmetrical views in which one part is a mirror image of another. Primary centerlines are
used as major locating lines to help in making
the views. They are also used as base lines for
dimensioning. Secondary centerlines, marked
S in Figure 4-28, are used for drawing details
of a part.
Primary centerlines are the first lines to be
drawn. The views are developed from them.
Note that centerlines represent the axes of
cylinders in the margin view. The centers of
circles and arcs are located first so that measurements can be made from them to locate
the lines on the various views. As you may
recall from the previous section, when a hidden line falls on a centerline, the hidden line
is drawn. When a hidden line falls on a visible
line, draw the visible line.
B
FULL LINE IN FRONT
SPACE
C
LEAVE SPACE FOR NEAREST LINE
Figure 4-27
Technique for presenting hidden and visible
lines
Identify What drafting tools are used to
draw vertical lines?
CL
P
S
S
S
S
P
P
Figure 4-28
Primary and
secondary
centerlines
S
S
CL = CENTERLINE
P = PRIMARY CENTERLINE
S = SECONDARY CENTERLINE
Section 4.2 Creating a Drawing
109
Ann Garvin
Working with Drawing
Instruments
How can you further improve the accuracy
of your drawings?
The correct use of drawing instruments
plays an important role in creating an accurate drawing. The following paragraphs
explain how to use the basic drawing
instruments.
PERPENDICULAR
TO SURFACE
Using the Dividers
RADIUS OVER 2"
To transfer a distance using the dividers,
adjust the points to exactly the length to be
transferred, such as the radius of a circle or the
length of a line. Transfer the length by positioning the dividers at a new location.
You can also use the dividers to divide a
line, arc, or circle into equal parts. For example, to divide a line into three equal parts:
Figure 4-30
Adjusting the compass for large circles
the points of the dividers by an amount
about one third the distance. Then start
at the beginning of the line again.
6. If the last point overruns the end of the
line, decrease the distance between the
points by one third the extra distance.
1. Adjust the points of the dividers until
they seem to be about one third the
length of the line. To adjust the dividers, hold them between your thumb
and index finger. Set them to the desired
radius using your third and fourth fingers, as shown in Figure 4-29A.
2. Put one point on one end of the line and
the other point on the line, as shown in
Figure 4-29B.
3. Turn the dividers about the point that
rests on the line, as in Figure 4-29C.
4. Then turn them in the alternate direction, as in Figure 4-29D.
5. If the last point falls short of the end of
the line, increase the distance between
A
B
For four, five, or more spaces, follow the
same rules, but correct by one fourth, one
fifth, etc., of the overrun or underrun. You
can divide an arc or circle in the same way.
Using the Compass
As you may recall from Chapter 3, the compass is used to draw regular curves, such as
circles and circular arcs. Leave the legs of the
compass straight for radii under 2 (50 mm).
For larger radii, make the legs perpendicular (at a 90° angle) to the paper, as shown in
C
Figure 4-29
The dividers are used to divide and transfer distances.
110
Chapter 4 Basic Drafting Techniques
NEEDLE - POINT
LEG
PENCIL
LEG
D
Ted Mishima
LENGTHENING BAR
.38 +
DRAWING SURFACE
NEEDLE POINT EXTENDS SLIGHTLY
BEYOND THE LEAD POINT
Figure 4-31
Figure 4-32
Use the lengthening bar in compasses for circles
and arcs of large radii.
Adjusting the point of the compass
1. Locate the center of the arc or circle by
drawing two intersecting, or crossing, lines.
2. Lay off the radius by a short, light dash,
as shown in Figure 4-33A.
3. Adjust the compass setting to the radius,
as shown in Figure 4-33B.
4. When the radius is set, raise your fingers to the handle, as shown in Figure
4-33C.
5. Turn the compass by twirling the handle
between your thumb and finger. Start the
arc near the lower side and turn clockwise,
as shown in Figure 4-33D. As you draw
the curve, slant the compass a little in the
direction of the line. Do not force the needle point into the paper. Use only enough
pressure to hold the point in place.
Figure 4-30. When you need a radius of more
than 8" (200 mm), insert a lengthening bar as
shown in Figure 4-31 to increase the length
of the pencil leg, or use a beam compass.
To get the compass ready for use, sharpen
the lead as shown in Figure 4-32, allowing
it to extend about .38" (10 mm). Then adjust
the shouldered end of the needle point until
it extends slightly beyond the lead point,
as shown in Figure 4-32. You cannot use as
much pressure on the lead in the compass as
you can on a pencil. Therefore, use lead one
or two degrees softer in the compass to get
the same line weight. Line weight refers to
the thickness and darkness of a line.
To draw a circle or an arc with the compass,
follow these steps:
A
B
C
D
Figure 4-33
Technique for drawing circles and arcs
Section 4.2 Creating a Drawing
111
Ann Garvin, Arnold and Brown
Using the Bow Instruments
Bow Pencil
The bow pencil is used to draw small circles. Whether you use instruments with center wheels or with side wheels is up to you.
Sharpen and adjust the lead for the bow pencil, as shown in Figure 4-34A. The inside
bevel holds an edge for small circles and arcs,
as shown in Figure 4-34B. For larger radii,
the outside bevel shown in Figure 4-34C
is better. Some drafters prefer a conical center point or an off-center point, as shown in
Figure 4-34D, E, and F.
Use the bow pencil with one hand. Set
the radius as shown in Figure 4-35A. Start
the circle near the lower part of the vertical
centerline, as shown in Figure 4-35B. Turn
clockwise. (Left-handers will need to reverse
this procedure.)
Drop-Spring Bow Compass
Use the drop-spring bow compass to draw
very small circles, as shown in Figure 4-36.
Attach the marking point to a tube that slides
on a pin. Set the radius with the spring screw.
To use the drop-spring bow compass, first
set the radius with the adjusting screw. Keep
the pin still and turn the lead around it. Hold
the marking point up while putting the pin
on the center. Then drop the marking point
and turn it.
Adjusting Bow Instruments
You can make large adjustments quickly
with the side-wheel bows by pressing the fork
and spinning the adjusting nut. Some centerwheel bows are also built for making large,
rapid adjustments. To do this, hold one leg
in each hand and either push to close or pull
Figure 4-34
Bevels and points
A
112
B
C
D
E
F
Chapter 4 Basic Drafting Techniques
A
B
Figure 4-35
Adjusting the radius for the bow pencil compass
to open. Make small adjustments with the
adjusting nut on both the side-wheel and the
center-wheel bows.
List What are the steps involved in drawing a
small circle with a drop-spring bow compass?
Using Irregular Curves
To use an irregular curve, find the points
through which a curved line is to pass. Then
set the path of the curve by drawing a light
line, freehand, through the points. Adjust it
as needed to make the curve smooth. Next,
match the irregular curve against a part of
Figure 4-36
The drop-spring
bow compass is
used for drawing
very small circles,
especially when
there are many to
be drawn.
2
1
1
B
A
SECOND POSITION
FIRST POSITION
3
2
1
C
THIRD POSITION
Figure 4-37
Steps in drawing a smooth curve
the curved line, as shown in Figure 4-37A,
and draw part of the line. Move the irregular curve to match the next part, and so on,
as shown in Figure 4-37B and C. Each new
position should fit enough of the part just
drawn to make the line smooth. Note whether
the radius of the curved line is increasing or
decreasing and place the irregular curve in the
same way. Do not try to draw too much of the
curve with one position. If the curved line is
symmetrical, or mirrored around an axis,
mark the position of the axis or centerline on
the irregular curve on one side. Then turn the
irregular curve around to match and draw the
other side.
Applying Drawing Skills
How do abbreviations and symbols help in
drafting?
As you begin to work on the drawing problems at the end of the chapter, you will notice
the use of various abbreviations and symbols in
dimensions and notes on the assignment drawings. For example in Problem 6, Figure 4-55A,
you will notice such things as 2X, R44, and
Ø54. The 2X is used to specify two times or two
places. The 2X in a dimension or note means
that the item being specified appears twice on
that view or drawing. It eliminates the need to
repeat the dimension for each detail that has
identical size and shape.
The R44 specifies a radius of 44 millimeters
and the Ø54 specifies a diameter of 54 millimeters. Notice that there is no space between
the number and the symbol or abbreviation.
Notice also that, except for the use of the letter X, abbreviations and symbols are placed
before the size dimension. Also, there is no
space between the symbol or abbreviation
and the size dimension.
Symbols and abbreviations are a form of
drafter’s shorthand. They reduce the amount of
time and space needed to provide critical information on the drawing. A list of the most commonly used abbreviations and symbols can be
found in Appendix A.
Section 4.2 Creating a Drawing
113
Applying Basic Drawing Skills
Follow the procedure below to complete the
template drawing shown in Figure 4-38A.
1. Begin with an 11.00 17.00 drawing
sheet and prepare it with .40 borders on
the left, right, and bottom and a .60 border on the top.
2. Measure 3.80 from the left border line,
and from this mark measure 8.50 toward
the right.
3. Lay the scale on the paper vertically
near (or on) the left border line, make
a mark 2.50 up from the bottom border line, and from this measure up 5.50
more. The sheet will appear as in Figure
4-38B.
4. Draw horizontal lines 1 and 2 with the Tsquare and triangle, as shown in Figure
4-38C.
5. Lay the scale along the bottom line of
the figure, with the measuring edge on
the upper side, and make marks 1.70
apart. Then, with the scale on line 3 and
its measuring edge to the left, measure
from the bottom line two vertical distances, 2.50 and 1.50, as shown in Figure 4-38D.
6. Through the two marks, draw light horizontal lines.
7. Draw the vertical lines with T-square
and triangle by setting the pencil on the
marks on the bottom line and starting
and stopping the lines on the proper horizontal lines, as shown in Figure 4-38E.
8. Erase the lines not wanted (if necessary)
and darken the lines of the figure to finish the drawing. Figure 4-38F shows the
finished template. Do not add dimensions unless instructed to do so.
Identify What does the notation ‶2X″
indicate on a drawing?
B
C
1
3
4
2
Figure 4-38
D
Template for drawing practice
A
1.70
1.70
1.70
1.70
E
1.50
3.00
5.50
F
3.80
8.50
2.50
114
Chapter 4 Basic Drafting Techniques
Working with CAD
Commands
Which basic CAD commands are needed to
create a simple CAD drawing?
The commands in a CAD program are the
“tools” the CAD operator uses to create drawings. Instead of using a T-square and triangle
to create a 45° line, for example, the CAD
operator uses the LINE command to create the
line and specifies a 45° angle. Commands vary
among CAD programs, and sometimes even
among different versions of AutoCAD and
AutoCAD LT. Therefore, if you see a command
in this text that does not appear in your software, use the software’s Help feature to find
out which command you should use instead.
However, within AutoCAD and AutoCAD LT,
most of the basic commands are the same.
The sections that follow explain how to use
basic drawing commands in AutoCAD. As you
read each section, pause and try out the technique in AutoCAD before continuing to read.
Drawing Straight Lines
Draw straight lines in AutoCAD by entering
the LINE command. The Command prompt
(at the lower left corner of the screen) asks
for the first point of the line. For now, use the
mouse to pick a point anywhere in the drawing area. The prompt changes to ask for the
next point. Pick another point, and another.
As you can see, you can continue picking
points to create line segments indefinitely.
A
When you are finished, press Enter to leave
the LINE command.
Horizontal and Vertical Lines
AutoCAD allows you to create perfectly
vertical and horizontal lines with very little
effort. The Ortho mode forces every line
you draw to be either vertical or horizontal,
as shown in Figure 4-39. To turn Ortho on,
pick the Ortho button at the bottom of the
screen, or press the F8 function key on the
keyboard.
Inclined Lines
The simplest way to create inclined lines
accurately is to use polar coordinates. Polar
coordinates include a specified distance and
the angle at which the line should extend. For
example, suppose you have already entered
the LINE command and specified the first
point. Typing @2.50<45 when AutoCAD
prompts you for the next point creates a line
that extends 2.50 units at 45 degrees.
Notice the required format for polar coordinates. The @ symbol tells AutoCAD that this
coordinate will be relative to the last point
entered. The @ is followed by the length of
the line. The < symbol represents “angle,” and
the last number is the specified angle.
Polylines
All of the lines discussed so far, even those
whose ends join, are actually individual line
segments. For many manufacturing uses, the
lines must be joined into a single line. AutoCAD makes this possible by providing a polyline. A polyline is a line of any length, with
any number of defining points, that is considered by the software to be a single line object,
as shown in Figure 4-40. Polylines can
contain straight segments, curved segments,
B
Figure 4-39
Figure 4-40
The Ortho mode forces every line you draw to be
perfectly vertical or horizontal. In this illustration,
the points shown in magenta represent the
actual points picked by the CAD operator.
The black lines show how AutoCAD draws the
corresponding lines with Ortho off (A) and with
Ortho on (B).
Examples of
polylines
A
B
Section 4.2 Creating a Drawing
115
or both. To create a polyline, use the PLINE
command. Experiment with this useful command until you feel comfortable using it.
The options that appear at the Command
line after you enter the first point of a polyline
extend its usefulness. The most frequently
used options for most applications are the
Arc and Close options. Arc allows you to add
one or more curved segments to the polyline,
and Close joins the last point you entered to
the first point of the polyline. This creates a
perfectly closed shape, which is very important for use with computer-aided manufacturing (CAM) and computer numerical control
(CNC) systems.
Drawing Circles and Arcs
Circles and arcs are easy to create in AutoCAD. In general, to create a circle, use the
CIRCLE command. To create an arc, use the
ARC command.
The easiest way to create a circle or arc is
to specify a center point and a radius. The
radius of a circle or arc is the distance from
its center point to any point on the rim of
the circle or arc (see Figure 4-41). However,
you can also use other methods, depending
on how you need to incorporate the object
into the drawing. You can specify a center
point and diameter, for instance, or specify
two tangent objects and a radius. Experiment with the options of the CIRCLE and
ARC commands until you feel comfortable
using them.
accurate than just pointing to a place on the
screen to specify endpoints for lines, center
points for circles, and so on. One way to produce lines that meet exactly and are exactly
the right length is to use coordinate entry.
This is a fairly slow method, and it has a
major disadvantage: you must know or figure
out the exact coordinates for every defining
point in the drawing.
Fortunately, there are easier ways. AutoCAD provides two tools called snap and grid
to help you select points accurately. Snap
sets the distance intervals at which the cursor moves when you move the mouse. For
example, a snap of .25 allows you to enter
points at exactly .25-unit intervals. While the
snap is on and set to .25, you cannot accidentally enter a point at .23 unit from the previous point. Snap is like a magnet that attracts
points to the intervals you specify.
To turn the snap on, pick the Snap button at the bottom of the screen or press the
F9 function key. To set the snap interval,
enter the SNAP command at the keyboard.
You can set the X and Y intervals to the
same value or to different values. You can
also rotate snap to any angle, and you can
specify whether you want a standard or
isometric snap.
Using Snap and Grid
To create acceptable technical drawings,
you must use techniques that are more
CENTER
POINT
RADIUS
Figure 4-41
The simplest way to create a circle in AutoCAD is
to specify a center point and a radius.
116
Chapter 4 Basic Drafting Techniques
Coordinate Values
While the LINE command is active,
move the mouse and watch the lower
left part of the screen. The coordinate
values of the cursor position appear
there. Double click the values to turn
the coordinates on and off. Enter the
LINE command and then turn the
coordinates on and off more than
once to notice that the coordinates
can be shown either as coordinate
pairs or as polar coordinates. For most
work, polar coordinates are more useful. Use the coordinates with the snap
and grid to make your work go faster.
Figure 4-42
2.50
Setting snap and
grid values of .50
would help you
create this stencil
for the letter H
very quickly and
accurately.
1.50
2.50
1.50
2.50
1.50
Grid produces a nonprinting grid of dots
on the screen at intervals you specify. These
dots provide a visual reference for the CAD
operator. To turn grid on or off, pick the GRID
button at the bottom of the screen or press
the F7 function key on the keyboard. To set
the grid spacing, enter the GRID command at
the keyboard. You can set the X and Y settings
to the same interval or to separate intervals
(using the Aspect option). You can also set
them to correspond to the snap settings.
By setting up snap and grid intervals that will
be useful in your current drawing, you can cut
down on drawing time. For example, to create
the stencil shown in Figure 4-42, you could set
the snap and grid to equal intervals of .50.
Erasing
Erasing in AutoCAD takes two forms. You
can either use the ERASE command, or you can
simply “undo” one or more of your actions.
When you enter the ERASE command,
AutoCAD asks you to select the objects to be
erased. You can pick them one by one with
the mouse, or you can create a window by
picking two diagonal corners of a rectangle.
All objects inside the rectangle are selected for
erasure. When you have finished selecting the
objects to be erased, press Enter to complete
the command.
AutoCAD has a formal UNDO command
that has several options. However, CAD operators usually just press the “u” key and then
Enter. This causes AutoCAD to undo the last
action you took. If you press “u” again, AutoCAD continues to undo the previous actions
sequentially. In this way, you can undo as
many steps as necessary until the drawing
reaches the state at which it was last saved.
This method can be used even in the middle
of many drawing commands, such as the
LINE command. This makes it a quick and
easy way to correct mistakes without stopping
to enter another command or losing your
train of thought.
Explain How do AutoCAD’s snap and grid
features allow for greater accuracy?
Creating the Layout in Paper
Space
Unless you have used a template that
includes a pre-drawn or ISO border and title
block, you will need to create these items in
paper space before you can lay out the drawing properly in paper space for printing.
1. Pick the Layout1 tab at the bottom of
the drawing area to activate it. Notice
that the stencil you created appears on a
paper-like background inside a rectangle.
In paper space, drawings actually appear
in viewports. Viewports are invisible
windows in the drawing area in which a
view of the drawing can be placed. The
rectangle is the default viewport. However, it is not the right size for an A-size
sheet.
2. Enter the ERASE command, select the
viewport, and press Enter to delete it.
The stencil disappears also, because
model-space geometry requires a viewport to display in paper space. However,
the stencil still exists in model space. You
will create a new viewport to display the
drawing properly, but first, you should
add a border and title block.
3. Switch to the Border layer by selecting it
in the Layer Control drop-down box in
the Layers toolbar or on the Dashboard.
4. Referring to the margin sizes in Table 4-1
on page 93, use the LINE or PLINE command to create a border for a horizontal
A-size sheet.
5. Create a title block in the lower right corner of the drawing sheet, with its bottom
and right sides aligned with the border.
6. Switch to the Viewports layer.
Section 4.2 Creating a Drawing
117
7. Enter the VPORTS command to create a
new viewport. Select the Single option
and pick OK.
8. Follow the prompts to create a rectangle
the size of the border you created earlier.
This will be the new viewport.
The stencil now reappears, but it is
scaled arbitrarily to fit in the viewport.
We want it to display on the drawing
sheet at a scale of 1:1.
9. Click once on the viewport (the magenta
rectangle) to select it. Then right-click
and select Properties from the shortcut
menu to display the Properties palette.
10. Pick the box next to Standard scale to
activate the text box and display an
arrow, as shown in Figure 4-43. Pick
the arrow and select 1:1 to set the drawing scale.
11. If the stencil overlaps the title block, pick
the PAPER button on the status bar to
return to model space within the layout.
Enter the PAN command to move the
stencil to a better location in the viewport. Pick and hold with the mouse button while you move the geometry.
The stencil is now properly displayed
at full scale. To complete the drawing,
you have only to add the appropriate
text to the title block.
12. Enter the TEXT command and complete
the title block. Title the drawing STENCIL,
put your school name in the COMPANY
NAME AND ADDRESS block, specify a
drawing size of A and a scale of 1:1. In the
SHEET area, enter SHEET 1 OF 1.
13. Right-click on the Layout1 tab to display
the shortcut menu and select Rename.
Give the layout a descriptive name such
as A – STENCIL.
14. Save the drawing.
If a drawing will not fit on the drawing
sheet you have selected, you will need to use
a different drawing scale. The procedure is the
same as for creating a full-scale drawing. Just
change the scale in the Properties palette to
the correct scale.
Printing the Drawing
After you have set up the drawing in paper
space and entered the appropriate information in the title block, you are ready to print
the drawing.
1. Enter the LAYERS command and pick the
sun icon in the Viewports row to freeze
Figure 4-43
To change the scale
of a drawing in paper
space without changing
the size of the border
and title block, change
the properties at the
viewport in which the
drawing appears. (A)
Select Viewport to see
the list of properties for
the viewport. (B) Select
the scale at which you
want the drawing to
appear.
118
Chapter 4 Basic Drafting Techniques
the Viewports layer. This will prevent the
viewport rectangle from printing, but the
stencil in the viewport will plot because
it is on the Objects layer.
2. Enter the PLOT command. Check the
printer settings, and make sure the plot
scale is set to 1:1. Then pick OK to print
the drawing.
Explain How are viewports used to scale a
drawing in AutoCAD?
Applying the Concepts
In what ways are board-drafting techniques
different than CAD techniques?
Practice is required to gain the skill
needed to create accurate technical drawings using CAD. The following procedure
steps you through the process of creating a
drawing of the template shown in Figure
4-44. This is the same drawing that is used
in the “Board Drafting Techniques” section
of this chapter. If you are completing both
procedures, notice the differences and similarities between the board drafting and CAD
techniques.
1.75
1.75
1.75
1. Create a new drawing using AutoCAD’s
ASME B template.
2. Switch to model space and set up the
units. For this drawing, use decimal units
with a length precision of two decimal
places and an angle precision of zero decimal places.
3. Set the model-space limits. This drawing
will be printed at full size, so the limits
should equal the sheet size.
4. Create the appropriate layers. This is a
fairly simple drawing that contains only
visible lines. You will not dimension
this drawing, so you really only need an
Objects layer. Create the layer and set it
up for visible lines .30 mm thick. Leave
the layer color at White.
5. Set the snap and grid. Review the template in Figure 4-45 and notice that all
of the decimals are in multiples of .25.
Therefore, .25 would make a good setting
for the snap and grid.
6. Save the drawing before you proceed.
Give it a name that is easy to identify,
such as Chapter 4 Practice, or name it
according to your instructor’s directions.
7. Refer again to Figure 4-45 to figure out
where to start drawing. In this case, a
convenient place to start is the lower
left corner of the template. Notice that
it is 3.25 from the left side of the border. This becomes the X coordinate for
1.75
1.50
Figure 4-44
3.00
5.50
3.75
Template for
drawing practice
8.75
2.25
Section 4.2 Creating a Drawing
119
90°
ORIGIN
180°
0°
X AXIS
270°
Y AXIS
Figure 4-45
Polar coordinates. Notice that 0° lies to the right
of the origin along the X axis. The angle value
increases counterclockwise through a complete
circle.
your starting point. It is 2.25 from the
bottom, so 2.25 becomes the Y coordinate for the starting point. Therefore,
the coordinates for the starting point are
(3.75,2.25).
There are two ways to proceed from here.
You can determine the exact coordinates
of each of the remaining endpoints on the
drawing, or you can use polar coordinates.
The easier method, used in this exercise, is
the polar coordinates method. Figure 4-45
shows the polar values for the angles you will
need to specify. In general:
prompt, for example, enter @8.75<0.
This draws an 8.75 horizontal line to the
right from the first point.
10. For the second point, you will need to do
a minor calculation. The length of the
line is the total length 5.50 less the 1.50
inset. Subtracting 1.50 from 5.50 equals
4.00, so the next line should be 4.00
drawn vertically bottom-to-top. Therefore, you should enter @4.00<90.
11. Calculate and enter the remaining values on your own. After you have entered
the last value, press Enter to end the
LINE command. Your finished template
should look like the one in Figure 4-45,
without the dimensions.
12. Pick the layout view tab to see how the
drawing looks on the sheet layout. The
drawing should appear to be the correct
size for the drawing sheet, but it may
seem a little off-center. You can change
the position of the drawing on the drawing sheet by selecting the viewport and
entering the PROPERTIES command.
• At the top of the dialog box, select Viewport.
• A line drawn horizontally to the right has
an angle of 0°.
• A line drawn horizontally to the left has an
angle of 180°.
• A line drawn vertically bottom-to-top has
an angle of 90°.
• A line drawn vertically top-to-bottom has
an angle of 270°.
8. Enter the LINE command, and use the
mouse to move the cursor until the
coordinate display in the lower left
corner shows the coordinates to be
3.75,2.25,0.00. (The third number is for
three-dimensional drawings only, so you
can ignore it for this drawing. Its value
will always be 0.00.) Click to set the first
point of the line at 3.75,2.25.
9. Work counterclockwise to draw the lines
for the template. At the first Next point
120
Chapter 4 Basic Drafting Techniques
Figure 4-46
The properties Center X and Center Y allow you
to center the drawing on the drawing sheet for a
pleasing display.
• Scroll down the list until you see Center X
•
•
and Center Y, as shown in Figure 4-46.
These refer to the horizontal and vertical
centers of the drawing.
You can change the defaults either by
entering a new numerical value or by using
the mouse.
To use the mouse, pick the icon at the right
of the current value. A line appears in the
viewport.
Section 4.2 Assessment
After You Read
Self-Check
1. List the basic drafting tools and equipment used by the drafter.
2. Name the line and line symbols recommended by ASME.
3. Identify the basic commands used to
set up a drawing on a CAD system.
4. Describe the correct hand positions for
drawing lines with a technical pen and
with a drafting pencil.
5. List the steps used to draw a circle with
a compass.
Academic Integration
Mathematics
6. Calculate Average Work Time Three
drafting students spent a total of four
hours working together to prepare a set
of mechanical drawings. What is the
average number of minutes each student
spends on the drawings?
Use Variables and
Operations
Translating words into algebraic expressions requires knowledge of the meaning of the verbal descriptions. In algebra,
a variable is a symbol used to represent a
number. Arithmetic operations include
addition, subtraction, multiplication,
and division. If x = the average number of hours each worker spends on the
drawings, the algebraic expression for the
problem is 3x = (4 60).
• The origin of the line is the current horizontal or vertical center.
• Move the mouse and click to select a new
center.
13. Save the drawing file. If your instructor requires a printed copy, print the
drawing. See pages 118 and 119 under
the heading “Printing the Drawing”
for more instructions on printing a
drawing.
Drafting Practice
7. Draw the item shown in Figure 4-47
below. Use the specified sheet size and
scale. Do not dimension.
.75
1.75
5.00
1.50
5.50
12.00
7.00
5.50
3.25
SHEET SIZE: B
SCALE: FULL SIZE
Figure 4-47
8. Draw the frame shown in Figure 4-48.
Locate all centerlines before beginning to
draw the frame.
4x R40
4x R60
4x R30
60
1.00
134
268
Figure 4-48
Go to glencoe.com for this
book’s OLC for help with this
drafting practice.
Section 4.2 Creating a Drawing
121
4 Review and Assessment
Chapter Summary
Section 4.1
Section 4.2
• Preparing the drawing sheet includes
•
•
•
•
choosing an appropriate size and type of
drawing sheet, fastening it to the drawing
board, and laying out the borders and title
block.
Preparing a drawing file in CAD includes
creating a new drawing, selecting a drawing template for the appropriate standard
sheet size, and setting up units, limits, and
layers.
Layers in AutoCAD have specific properties such as line width, linetype, and color.
Commands are the drafting tools used in
a CAD program.
Technical drawings created in CAD can
be printed using ASME or ISO standard
layouts in paper space.
• The use of a drafting pencil differs from
the use of a technical pen.
• The lines and line symbols used on drawings come from the alphabet of lines.
• Techniques for drawing circles, arcs, lines,
•
and inclined lines require the use of a
compass, circle template, T-square, protractor, drop-spring bow compass, dividers
or triangle.
In a CAD system, the LINE, ORTHO, polar
coordinate, and PLINE commands are
used to produce straight lines, vertical or
horizontal lines, inclined lines, and to
join lines into a single line, respectively.
The CIRCLE and ARC commands are
used to produce circles and arcs. Grid and
snap commands produce lines that meet
exactly.
Review Content Vocabulary and Academic Vocabulary
1. Use each of these content and academic vocabulary words in a sentence or drawing.
Content Vocabulary
• sheet layout (p. 91)
• reference zones (p. 92)
• revision history block (p. 92)
• application blocks (p. 92)
• drawing templates (p. 96)
• model space (p. 96)
• paper space (p. 96)
• limits (p. 97)
•
•
•
•
•
•
•
•
•
layer (p. 98)
inking (p. 103)
alphabet of lines (p. 105)
inclined lines (p. 106)
hidden lines (p. 108)
centerlines (p. 109)
line weight (p. 111)
symmetrical (p. 113)
Ortho mode (p. 115)
•
•
•
•
•
•
polar coordinates (p. 115)
polyline (p. 115)
radius (p. 116)
snap (p. 116)
grid (p. 117)
viewports (p. 117)
Academic Vocabulary
• appropriate (p. 91)
• differentiate (p. 108)
Review Key Concepts
2.
3.
4.
5.
6.
7.
122
Describe how to prepare a drawing sheet for a technical drawing.
Define the alphabet of lines.
Explain how the use of the drafting pencil and pen differs.
Describe how to use the compass and the dividers.
Explain how the snap and grid tools function in AutoCAD.
Explain how basic geometry is created to produce a technical drawing with CAD commands.
Chapter 4 Basic Drafting Techniques
Technology
8. Moving from Paper to Electronic
The Bechtel Group is a large international
engineering and construction company.
Among many of its achievements are the
Hoover Dam and the “Chunnel” that runs
underneath the English Channel. As projects
are designed and reviewed, the company is
migrating from paper to primarily electronic
drawings. For an international company with
marketing, legal, engineering, and construction groups, what advantages or disadvantages do you think accompany this change?
Write a one-page paper explaining your ideas.
True/False Questions
Prep
For
Directions Read the following
statements and determine
whether each statement is
true or false.
11. Parts of a drawing that cannot be
seen in the views are drawn with
centerlines.
T
F
12. A revision history block specifies revision dates and related information.
T
F
TEST-TAKING TIP
9. Ethics and Design
You have been asked to design a desk that
will be used in schools nationwide. Your
manager asks you to consider the materials that the desks will be made from. Plastic
laminates, wood, and particle board are some
of your options. What issues might you consider in regard to construction costs, the
environment, and safety? Give a five-minute
presentation that details how you selected the
materials for your design.
Mathematics
10. Calculate Dimensions
At her new job, Tina has been asked to calculate the dimensions of the boxes for a new
line of kitchenware. The volume of the boxes
can be no more than 1,800 cubic inches. To
accommodate the products, the length must
be 15 inches and the height 10 inches. What
should the width of the boxes be?
Dimension and Volume
To calculate the volume of a three-dimensional figure, use the formula V l w h.
Use the information that you have to create
an equation for the volume of the box. Use
w to represent the width. V 15 w 10.
Solve for w.
Read statements slowly and carefully. If any
part of the statement is not accurate, then
the entire statement is false. For the statement to be true, every part must be true.
Win
Competitive
Events
13. Job Interview
Organizations such as SkillsUSA offer
a variety of architectural, career, and
drafting competitions. Completing activities such as the one below will help you
prepare for these events.
Activity Imagine an interviewer says,
“Tell me about a mistake you made at
work, and how you handled it afterwards.” Write four sentences describing
how you could answer this question in
a way that shows resourcefulness and a
positive attitude.
Go to glencoe.com for this book’s
OLC for more information about
competitive events.
Review and Assessment
123
4 Problems
Drafting Problems
The problems in this chapter can be performed using board drafting or CAD
techniques. The problems are presented in order of difficulty, from least to
most difficult. Begin by drawing a border and title block if instructed to do so.
1.
Draw each item shown in Figure 4-49
using the specified sheet size and scale.
Do not dimension.
25
125
75
276 12
5.00
316
1.50
12
1.75
60 70
50
100
12
1.50
200
METRIC
12412
200
8.00
200
12
94
96
416
A
B
SHEET SIZE: A4
SCALE: 1:1
SHEET SIZE: A
SCALE: FULL SIZE
C
METRIC
SHEET SIZE: A4
SCALE: 1:2
6
4.80
1.50
1.75
8.00
1.00
1.50
.20
1.40
6.26
6.00
1.50
1.75
1.60
1.00
.25
1.50
4.80
1.00
1.75
172
8.00 SQ
.20
4.00
5.00
1.40
.25
•
.40
1.00
1.50
.20
(TYP)
D
E
SHEET SIZE: A
SCALE: FULL SIZE
SHEET SIZE: A
SCALE: 3/4 SIZE
Figure 4-49
124
132 SQ
6.00
1.60
6.26
2.20
.40
2.26
Chapter 9 Basic Drafting Techniques
SPACE LINES
3 mm APART
6 (TYP)
15 SQUARE (TYP)
F
SHEET SIZE: A4
SCALE: 1:1
METRIC
2.
4.
Draw the grill plate shown in Figure
4-50. Make all ribs 12 mm wide. The distance AB is 59 mm; BC is 88 mm; AD is
64 mm. The diamond shapes are 38 mm
square. Sheet size: A4. Scale: 1:1.
Practice using a civil engineer’s scale by
drawing the land parcel shown in Figure
4-52. Measure the length of the closing
line to the nearest tenth of a foot and
note it on your drawing. Sheet size: B. 1
40-0.
F
E
C
105°
A
B
C
AB = 600'
BC = 340'
CD = 280'
DE = 105'
EF = 100'
FG = 75'
GH = 120'
HA = ?
F
90°
90°
AB = 55 mm
BC = 90 mm
AD = 200 mm
AE = 65 mm
AF = 130 mm
K10 = 10 mm
D Dimensions 40mm
G
60°
D
E
90°
H
CLOSING
LINE
90°
75°
METRIC
Figure 4-50
B
A
Figure 4-52
3.
The drawing in Figure 4-51 provides
practice in metric measurement. Draw
horizontal line AB 180 mm long. Work
clockwise around the layout. Remember: Angular dimensions are the same in
the U.S. Customary and metric systems.
Measure the closing line and measure
and label the angle at H. Sheet size: A4.
Scale: 1:1.
5.
Draw the head gasket shown in Figure
4-53. Scale: 1:1.
D
C
F
F
E
C
E
A
B
AB = 90 mm
C = R60 mm
D = R40 mm
E = Ø60 mm
F = Ø90 mm
G = Ø20
F
E
60°
75°
C
D
90°
90°
D
H
G – 7 HOLES
G
90°
CLOSING LINE
120°
B
75°
A
AB
BC
CD
DE
EF
FG
GH
=
=
=
=
=
=
=
180 mm
60 mm
48 mm
42 mm
74 mm
50 mm
90 mm
Figure 4-53
METRIC
Figure 4-51
Problems
125
4 Problems
6.
Draw each item in Figure 4-54. Before you begin each drawing, determine a suitable sheet
size and scale. Include all centerlines. Do not dimension.
2X
Ø24
4X
Ø.62
Ø54
R64
R.75
R.56
2.50
4.50
.75
R44
METRIC
150
6.00
8.00
B
A
2X
Ø38.10/1.50
R53.98/2.125
4X
Ø16
EQUALLY
SPACED
Ø44
Ø136
Ø98
R82.55/3.25
C
METRIC
MM; MM/IN.
IN.
127.00
5.00
D
10X18
96
120
3
4X .70
1.00
4
30º
.60
.50
30°
1.88
15º
Ø1.88
4.00
4X
Ø.62
15°
5
3 2
5
1 Ø76
72
1
Ø58
6
R.62
2X R.80
6
77
10X
Ø12
88 9
0
Ø36
0
9
Note:
numbers
are6 10mm
high
NOTE:
NUMBERS
ARE
mm HIGH
4.38
E
4
2
4.40 SQ
F
METRIC
3X
Ø.56
Ø2.25
15.8
.62
4X
Ø19/.75
120.6
4.75
30°
Ø4.50
1.12
3.88
57.2
2.25
R.62
R9.53/.38
152.4
6.00
G
METRIC
Figure 4-54
126
Chapter 4 Basic Drafting Techniques
H
R19/.75
MM
; MM/IN.
IN
7.
Draw each item in Figure 4-55. Determine a suitable sheet size and scale. Include all centerlines. Do not dimension.
2X
Ø44.45/1.75
180
82
60
28
58
58 112
29
3X Ø14
139.70
5.50
MM ; MM/IN.
IN.
R57.15/2.25
58
A
B
METRIC
R42
R66
2X
Ø2.75
R1.12
R1.12
R2.00
R.50
R1.00
R12
88
R12
60°
96
60°
3.50
4X
Ø.75
24
48
190
3.38
7.50
C
METRIC
8.
D
Figure 4-55
Draw the offset bracket shown in Figure 4-56. Locate all center points before beginning to
draw circles and arcs. Do not dimension.
10.62
R1.12
R.62
1.68
1.75
(2.25)
(7.12)
R2.88
2X
O 1.00
Figure 4-56
Problems
127
4 Problems
9.
Draw each item shown in Figure 4-57. Locate and mark points of tangency. Determine an
appropriate sheet size and scale. Include all centerlines. Do not dimension.
4.60
O .60
5 HOLES
EQUALLY SPACED
2.62
POINT
R2.12OF
TANGENCY
STRAIGHT
4.75
LINE
R 5.00
R3.50
2.50
R1.25
POINTS OF 6.00
TANGENCY
2.50
R 3.50
.06
R2.50 1.38
.25
R.50
O 5.96
R 1.30
O 4.78
.10
1.00
R.61
.3
1.28
O 3.40
5.50
11.00
11.00
A
1.00
O1.50
R 1.50
1.00
2x R .24
R.25
R1.50
.75
.50
.50
B
.50.50
O1.00
.50
R1.25
R 1.00
R 1.00
1.50
2.00
4.70
R64
C
7X R6
30° 12
O30
R52
19
15°
O22
30°
30°
O34
Ø110
O16
86
METRIC
NOTE: SMALL RADII R6
D
O.88
3 HOLES
EQUALLY SPACED
Ø76
Ø48
O3.20
O4.40
O5.20
E
4X R8
METRIC
F
Figure 4-57
128
Chapter 4 Basic Drafting Techniques
6X
R.80
R1.00
10.
Draw the multiple dial plate shown in
Figure 4-58. Create the centerlines at
right angles. Distances FC, FD, FG, FE,
EA, and GB are 6.00 each. The diameter
of the inner ring with center F is 4.50.
Diameters of all other inner rings are
4.00. Scale: 3 1-0 (1:4).
12.
Draw the pawl shown in Figure 4-60.
Scale: 1:1.
2X R.50
R3.00
R1.00
2X
R.50
5.50
1.00
.50
H
C
1.00
4X R.50
O1.00
4.00
2.50
8.50
A
E
F
G
B
Figure 4-60
D
Figure 4-58
Draw the tilt scale shown in Figure 4-61.
Scale: 1:1.
R.30
R.20
R2.90
2X R
R 3.50
R2.00
R3.80
30
13.
30
Draw the double dial plate shown in
Figure 4-59. Line AB = 7.00, and distances AC, CD, and DB are equal. Radii
of inner arcs with centers at C and D 1.50 and 1.70, respectively. Radii of
outer arcs with centers E and F are 3.70
and 3.90 respectively. Scale: Full size.
45
45
11.
60
75
90
75
60
F
Figure 4-61
A
C
D
B
E
Figure 4-59
Problems
129
4 Problems
F
14.
Construct the irregular polygon shown in Figure 4-62.
Begin by drawing line AA
centered near the bottom of
the sheet. The length of each
line is given in millimeters
at the right of the polygon.
Scale: 1:2.
105°
135°
H
H
E
105°
D
D
C
C
I
60°
60°
270°
75°
75°
B
Figure 4-62
15.
F
105°
105°
135°
E
G
G
Draw the wire rope hook shown in
Figure 4-63 using the dimensions selected
by your instructor. Determine the radii
necessary for smooth tangencies.
B
150°
150°
AA = 140
AB = 90
BC = 80
CD = 90
DE = 40
EF = 50
FG = 100
GH = 60
A
A
16.
Draw the adjustable link shown in
Figure 4-64. Scale: 1:1.
R. 40
2x R. 50
C
1.80 DIA
.750 DIA
15º
R. 80
1.30
30º
D
R 3.40
A
.88 DIA
R .70
4.00
5.60 TO BORDER
E
METRIC
B
Figure 4-64
Wire Rope Hook
A
B
C
D
E
4.94
3.20
.88
1.06
.84
5.44
3.50
1.00
1.12
.90
6.25
4.10
1.12
1.25
1.12
6.88
4.54
1.25
1.38
1.30
7.62
4.88
1.38
1.50
1.38
8.60
5.75
1.50
1.70
1.56
9.50
6.38
1.16
1.88
1.70
Figure 4-63
130
Chapter 4 Basic Drafting Techniques
1.50 TO TITLE BLOCK
R
Ø.38 SLOTS
17.
R.30
.24
.38
R.34
R.48
2.24
1.00
1.12
.36 .43
.24
3.96
ROUNDS AND FILLETS R.06
MATL – MALLEABLE IRON
6.50
.80
2.36
.2X
Ø.64
Draw a gasket for the bottom
of the guide block shown
in Figure 4-65. It should
be shaped so that when cut
out, it will touch only the
metal surface on the bottom.
Scale: 1:1.
R.64
1.80
.38
.16
1.00
.36
Figure 4-65
Design Problems
Design problems have been prepared to challenge individual students or
teams of students. In these problems, you are to apply skills learned mainly
in this chapter, but also in other chapters throughout the text. The problems
are designed to be completed using board drafting, CAD, or a combination of
the two. Be creative and have fun!
Challenge Your Creativity
Teamwork
1.
3.
Design a nightstand caddy to hold a
watch, wallet, coins, jewelry, and other
items. First, sketch your design ideas and
then prepare instrument or CAD drawings
as assigned. Do not dimension. Material:
Optional.
Teamwork
2.
Design a drawer divider to hold CDs and
DVDs. Inside drawer size: 6 deep 12
wide 26 long. Material: Optional. Do
not dimension. Each team member should
first develop design sketches. The entire
team should then select the best design
(or combined design). Finally, each team
member should prepare finished drawings
of the final design.
Design a fishing-tackle box. The design
team should first make a list of items
and quantities of items that the box is to
accommodate. Next, work in groups of
two or three to design individual sections
of the box. Then work as a full team to
put the sections together into a finished
box design. A cardboard version could
be made to help in visualizing the final
design. Material: 22-gauge galvanized
sheet metal. Do not dimension.
Problems
131