Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 1
Unit 2: Drafting Instruments
(Chapter2: Layouts and Lettering)
DFTG-1305 Technical Drafting
Instructor: Jimmy Nhan
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 2
OBJECTIVES
1. Identify the line patterns used in technical drawings and describe how they are used.
2. Identify standard drawing media and sheet sizes.
3. Label drawing scale information.
4. Identify drafting equipment and describe its usages
5. Fill in a standard title block with the appropriate information.
6. Lay out a drawing sheet.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 3
DRAWING PENCILS
High-quality drawing pencils help produce good quality technical
sketches and drawings.
Hard
The hard leads in thisgroup (left) are usedwhere extremeaccuracy is required,as on graphicalcomputations andcharts and diagrams.The softer leads in thisgroup (right) aresometimes used forline work onengineering drawings,but their use is limitedbecause the lines areapt to be too light.
Medium
These grades are for
general-purpose work in
technical drawing. The
softer grades (right) are
used for technical sketching,
lettering, arrowheads,
and other freehand work
on mechanical drawings.
The harder leads (left) are
used for line work on
machine drawings and
architectural drawings. The
H and 2H leads are widely
used on pencil tracings for
reproduction.
Soft
These leads are too
soft to be useful in
mechanical drafting.
They tend to produce
smudged, rough lines
that are hard to erase,
and the lead must be
sharpened continually.
These grades are used
for artwork of various
kinds, and for full-size
details in architectural
drawing.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 4
ALPHABET OF LINES
Thick and Thin Drawing Lines
Freehand line technique
Line styles
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 5
More
LINES
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 6
FREEHAND LINESThe main difference between an instrument or CAD drawing and a freehand sketch is
in the appearance of the lines. A good freehand line is not expected to be precisely
straight or exactly uniform, as is a CAD or instrument-drawn line. Freehand lines show
freedom and variety.
Freehand construction lines are very light, rough lines. All
other lines should be dark and clean.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 7
STANDARD SHEETS
There are ANSI/ASME standards for international and U.S. sheet sizes.
Note that drawing sheet size is given as height width. Most standard
sheets use what is called a “landscape” orientation.
* May also be used as a vertical sheet size at 11" tall by 8.5" wide.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 8
Typical Sheet Sizes and Borders
• Margins and Borders
• Zones
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 9
Title Block
The title block is located in the lower right corner of the format.
Standard areas in the title block provide the information as shown
below.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 10
PLANNING YOUR DRAWING OR SKETCH
When laying out a drawing sheet, you
will need to consider:
The size and scale of the object you
will show, the sheet size, the
measurement system (units) for the
drawing, the space necessary for
standard notes and title block.
The object you are drawing is the “star” of the sketch. Keep the object near the center of
the sheet. It should be boldly drawn, using thick visible lines. Make it large enough to fill
most of the sheet and so that details show clearly.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 11
MEASUREMENT SYSTEMS
U.S. Customary Units
The Metric System
Dual-Dimensioned
Today’s metric system is the International System of Units, commonly referred to as SI
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 12
DRAWING SCALE
Drawing scale is the reduction or enlargement of the drawn object
relative to the real object
Reduced and Enlarged Scale. Many drawings must be shown at reduced scale for the object to fit on the paper.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 13
SPECIFYING THE SCALE ON A DRAWING
List the predominant drawing scale in the titleblock. (Courtesy of Dynojet Research, Inc.)
For a part that is shown on the paper
at half its actual size, the scale is listed
in one of these three ways:
SCALE: 1:2
SCALE: 1/2
SCALE: .5
Architectural drawings list the scale based
on the number of fractions of an inch on the
drawing that represent one foot on the
actual object. Example:
SCALE: 1/8" 1'
Map scales are indicated in terms of
proportions such as Scale 1:62500,
fractions such as Scale 1∙62500, or
graphically, such as:
For machine drawings, the scale indicates
the ratio of the size of the drawn object to
its actual size, regardless of the unit of
measurement used. Expansion or
enlargement scales are given as 2:1, 4:1;
5:1, 10:1, and so on.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 14
SCALES
Scales are measuring tools
used to quickly enlarge or
reduce
Drawing measurements.
Types of Scales
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 15
METRIC SCALES
The triangular scales have
one full-size scale and five
reduced-size scales, all fully
divided.
Using these scales, a drawing
can be made full size,
enlarged sized, or reduced
sized.
Full Size 1:1 scale
Half Size 1:2 scale
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 16
ENGINEERS’ SCALES
An engineers’ scale (also called a civil engineers’ scales) is a decimal scale
graduated in units of 1 inch divided into 10, 20, 30, 40, 50, and 60 parts.
Because the engineers’ scale divides inches into decimal units, it is convenient
in machine drawing to set off inch dimensions expressed in decimals.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 17
MECHANICAL ENGINEERS’ SCALES
Triangular combination scales are available that include full- and half-size mechanical engineers’ scales, several architects’ scales, and an engineers’ scale all on one stick.
Mechanical engineers’ scales are divided into units representing inches to full
size, half size, quarter size, or eighth size.
To draw an object to a scale of half size, for example, use the mechanical
engineers’ scale marked half size, which is graduated so that ever ½” represents
1". In other words, the half-size scale is simply a full-size scale compressed to half
size.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 18
Architects’ ScaleThe architects’ scale is intended primarily for drawings of buildings, piping
systems, and other large structures that must be drawn to a reduced scale to fit on a
sheet of paper.
AutoCAD software users sometimes become confused using architectural units. When selecting architecturalunits and entering lengths, keep in mind that a value of 1 is one inch, not one foot.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 19
TEMPLATES
Templates are available for a great variety of specialized needs. Templates may be found for drawing almost any ordinary drafting symbol or repetitive feature.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 20
Drafting Equipment and its Usage
Adjustable drafting table is used to draw parallel, perpendicular
or oblique lines.
Technical Drawing with Engineering Graphics, 15th edition
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman 21
Drafting Equipment and its Usage (cont.)
Portable Drafting Board is used to draw parallel
Courtesy of Keuffel & Esser Co.