about engineering

2. OBJECTIVES – Standard VI
& Standard VII
 Interpret plans, diagrams, and working drawings.
 Apply appropriate technical and graphic
communication in the technological systems.
 Identify Line Types for the Alphabet of Lines
 Construct lines properly on drawings.
 Hierarchy of lines

3. ESSENTIAL QUESTIONS
 Why is drafting considered a universal language?
 Why is it important to recognize the alphabet of
lines?
 What is the hierarchy of lines?
 Why is it as well covered/included in welding?

4. Drafting as a Language
 Drafting is called a “universal language”
 Symbols (lines and figures) have specific meaning
are used.
 The symbols accurately describe the shape, size,
material, finish, and fabrication or assembly of a
product.

5. Drafting as a Language
 Drafting is also known as the “language of industry”
 Industry uses this precise language because the
drawings must communicate the information the
designer had in mind to those who produce the
product.

6. Why Study Drafting?
 Drafting is a form of graphic communication.
 “A picture is worth a thousand words.”
 Meaning - A picture tells a story just as well as a
large amount of descriptive text.

7. Significance in Welding
It relays a vital role to draft lay-out
in creating/construction of
framework or working sketch
It also provide a systematic
foundation for the actual size and
measurement of the product being
developed

8. “A picture is worth a thousand words.”
Steps for Drawing the Pink Panther
Draw the border and title block.
Find the center of the work space.
You can’t draw all the letters listed in alphabetical order.
Draw everything lightly at first & then go back and darken the drawing.
Darken in the eye pupils, eyebrows, & nose last to keep your draw neat.
The drawing on the handout is drawn proportional. That means you can use you compass on the handout to help
find center points. The measurements will not be the correct size, but you will be able to location where the center
points should be on the drawing.
Draw the following items in this order to make the drawing a little easier.
1. Draw A – 16 square boxes 1.5”
2. Draw B – 2” square box – This box isn’t centered on the page. The top of the box is located 5/9 of the
1.5”.
3. Draw the following letters next: C, D, E, G, I, J, the outer ear, & the bottom half to the large circle.
4. Draw the eye pupils. Start with the left pupil. Use a circle template to locate a circle that is tangent to
the left side & top of the 2” square. The right pupil is located on the outside right corner of the 2”
square. Extend the right corner of the 2” square to the 1.5” line.
5. Draw M – center for M is where the eye pupil is tangent to the circle C. Bring the center point used for
the left side straight across to the right eye.
6. Draw K – center for K is 3/9 of the 1.5”. K should be tangent to the eye & stops at a 20° from the center
of the circle.
7. Draw top arc of nose. The center for that arc is the top of G where the 1.5” line intersects the circle. The
arc size is tangent to D and will close to the center of the drawing.
8. Find point H. Swing the arc from the top center of the 2” square & the center of G. Where the two arcs
intersect is point H. Must find that point on both right & left side.
9. Draw the arc for the top nose arc between the eyes. Use point H to swing an arc starting at the center of
the 2” square.
10. Draw the dark part of the nose. Draw a 45° line from the center of the drawing. Where the 45° line
intersects the arc for the nose part between the eyes locates the center for the arc for the opposite side of
the black part of the nose. That arc size starts where the arc intersects the top of nose arc and stops on the
center line of the drawing.
11. Draw the top side parts of the head. The center of this part is located by bring point H straight across to
where it intersects the 1.5” line of the box below that section. The size of this arc for the head is tangent
to I.
12. Draw the lower part of the chin. Use the same center point located for drawing the top side part of the
head. The size of the arc is tangent to the opposite side of circle G.
13. Draw the bottom part of the head. The center point for this arc is located by bringing the top corner of
the 2” square straight across to the 1.5” line. The size of this arc for the head is tangent to I.
14. Draw the lower parts of the ears. The inside lower parts are just perpendicular line from the two circles.
The outside parts are going to be 60° lines tangent to the circles.
15. Draw the arc between the eyes for the top of the head. The center for this arc is the middle point between
point X & point Y. The radius of the arc is located 8.5/9 of the 1.5” line up from the center of the
drawing.
16. Draw arc F. Locate the center of arc F by first drawing a 45° line from the bottom corner of the 2”
square to where it intersects the circle D. Next swing arc F from that intersecting point on D & from the
top of the intersecting point of circle G with the 1.5” line. Where those two arcs intersect draw arc F.
17. Draw N. The center point for N is the center of the drawing. It stops straight across from point H. Draw
a 45° line to make the smile.
18. Draw L. To find the center points for circle L find points X & Y. The center for the top L is from the
midpoint between points X & Y. The arc starts on a 45° line from the center of the drawing and stops on
the bottom of the large circle. Point X is the center for the right inter L and point Y is the center for the
left inter L. The inter L starts on circle D and stops on the bottom of the large circle.

9. ALPHABET OF LINES
 Industry standard classifying the different types of
lines used in drawings.
 Developed by the American Society of Mechanical
Engineers (ASME).
 Lines are classified by line thickness and drawn thin or
thick.
 Thick lines are typically drawn with a 0.7 mm or 0.9 mm
mechanical pencil.
 Thin lines are typically drawn with a 0.3 mm or 0.5 mm
mechanical pencil.

10. LINE TYPES

11. CONSTRUCTION
 Used to initially lay out a drawing.
 Used for guide lines for lettering.
 Draw very light and thin so they are barely visible.
 Draw with a 0.5 mm pencil.

12. VISIBLE/OBJECT
These lines are thick
and dark solid
(unbroken) lines that
are used on drawings
to indicate the edges
and details of an
object.
These lines should be the most prominent on the
drawing as they are drawn thicker (wider) than most
other lines. We will use the 0.9 mm pencil.

13. HIDDEN
These lines are medium
dashed lines used to
indicate a surface, edge,
or contour of an object
that cannot be seen, or
is hidden from view.
The dashed lines are 1/8” long with a 1/16” space.
Hidden lines will be drawn with a 0.7 mm pencil.

14. CENTER
These lines are thin
lines made up of
alternating long and
short dashes. They are
used to indicate the
center of circles and of
symmetrical features.
Also as an aid in
dimensioning.
The short dashed lines are
1/8” long, the space is 1/16”, &
the long line ranges from 3/4”
to 1 ½”. Lines will be drawn
with 0.5 mm pencil

15. SECTION
Section lines are thin
“cross hatching” lines
used in sectional
views to symbolize
different parts of an
object or different
materials from which
an object is
manufactured.
Section lines are normally drawn
at a 45° with a 0.5 mm pencil.

16. DIMENSION, EXTENSION, & LEADER
These lines are thin
lines (0.5 mm)used for
dimensioning purposes.
Dimension and leader
lines generally end with
arrowheads and are
accompanied by a number
indicating a size or
location dimensions.
Extension lines aid dimension
lines by extending the surface
of the object so it can be
dimesioned.

17. CUTTING PLANE OR VIEWING
PLANE
These lines are very
thick lines (0.9 mm)
that indicate where an
imaginary cutting plane
passes through an
object, for viewing or
sectioning purpose.
Arrowheads on both ends of
the line point to the surface
to be viewed.

18. BREAK
These lines are used to
shorten a view, or to
eliminate repetitive
details when an entire
view is not necessary.
Short break lines are thick wavy freehand lines.
Long break lines are thin straight zigzags.

19. PHANTOM
These lines are thin
lines used to
indicate alternate
positions of moving
parts, lines of
motion, adjacent
parts and repetitive
details.
They are similar in style to a
Cutting Plane Line, but much
thinner in weight.

20. Hierarchy of Line
 It is not uncommon for line types to coincide or
overlap in a drawing.
 When visible lines, hidden lines, or center lines
coincide in the same view, a preferred line is
illustrated.
 That chosen line is determined by what is called
the Precedence of Lines.

21. Hierarchy of Line
 This list ranks the line type precedence from highest to
lowest:
Object or visible line
Hidden line
Cutting plane line
Center line
Break line
Dimension and extension lines
Sectioning lines

22. Hierarchy of Line
In the example you can see
where lines coincide with
one another line from the
front view to the side view.

23. Hierarchy of Line
The “X” lines are object
lines which overlap the
hidden line of the circles
(holes). The object line
has precedence over the
hidden line which means
the object line is drawn.

24. Hierarchy of Line
The “Y” line is an object
line which overlaps the
center line of the large
circle. The object line has
precedence over the
center line which means
the object line is drawn.

25. Hierarchy of Line
The “Z” line is a hidden
line. Although the center
line for the small circle
(hole) is in front of the
hidden line, the hidden
line has precedence over
the center line and is
therefore shown instead
of the center line.

26. REVIEW
 Why is drafting considered a universal language?
 Even though people around the world speak different
languages, the graphic language (symbols & line types)
has remained common.
 Why is it important to recognize the alphabet of
lines?
 The lines in the Alphabet of Lines are used to describe
shape, size, hidden surfaces, interior detail, and
alternate positions of parts.
 Each conveys a particular meaning on the drawing.
 What is the hierarchy of lines?
 The order in which lines are drawn when more than one
line type is located in the same location on a drawing.

27. REVIEW
 What line starts and ends with a dash?
 HIDDEN LINE
 What lines should be the most prominent on the
drawing?
 OBJECT LINE
 What line is drawn the lightest and thinnest for
laying out the drawing?
 CONSTRUCTION LINE