The document discusses the alphabet of lines used in technical drawings. It defines 11 types of lines: 1) object or visible lines, 2) construction lines, 3) dimension lines, 4) hidden lines, 5) center lines, 6) extension lines, 7) cutting plane lines, 8) short and long break lines, 9) leader lines, 10) phantom lines, and 11) section lines. It provides examples of how different line types would be used to draw geometric shapes like a pyramid, circle, cube, and cylinder.

1. Technical
Drawing: Alphabet
of Lines

2. TECHNICAL DRAWING: ALPHABET OF
LINES
Technical drawing, is the act and discipline of
composing drawings that visually communicate how
something functions or is constructed.
Line, can be defined as a straight one- dimensional
figure that has no thickness and extends endlessly in
both directions. It is often described as the shortest
distance between any two points.

3. OBJECT OR VISIBLE
LINES
- Thick dark line use to show
outline of object, visible edges
and surfaces.

4. CONSTRUCTION LINE
- Very light and thin
line used to construct
layout work

5. DIMENSION LINE
Thin and dark lines use to show
the size (span) of an object with a
numeric value. Usually terminates
with arrowheads or tick markings

6. EXTENSION LINE
Thin and dark line use to show the
starting and ending of dimension.

7. HIDDEN LINE
Short dash lines use to show non
visible surfaces. Usually shows as
medium thickness.

8. CENTER LINE
Long and short dash lines. Usually
indicates center of holes, circles
and arcs. Line is thin and dark.

9. CUTTING PLANE LINE
Extra thick line use to
show cutaway views or
plane of projection where
a section view is taken.
Arrow indicates direction
of view.

10. SECTION LINE
Medium lines drawn at
45 degrees use to
show interior view of
solid areas of cutting
plane line.

11. SHORT AND LONG BREAK
LINES
Short and long
medium line use to
show cutaway view of
a long section.

12. LEADER LINE
Medium line with
arrowhead to show
notes or label for size
or special information
about a feature.

13. PHANTOM LINE
Long line followed by
two short dashes use
to show alternate
position of a moving
part.

15. WHAT’S MORE?
ACTIVITY #5: LET’S TRY IT ON THE BOARD!
Directions: Draw the lines
needed to complete the
drawing plan of different
geometrical shapes.

16. WHAT’S MORE?
ACTIVITY #5: LET’S TRY IT ON THE BOARD!
PYRAMID:
HIDDEN
LINE

17. WHAT’S MORE?
ACTIVITY #5: LET’S TRY IT ON THE BOARD!
CIRCLE:
CENTER
LINE

18. WHAT’S MORE?
ACTIVITY #5: LET’S TRY IT ON THE BOARD!
CUBE:
EXTENSIO
N LINE
AND
DIMENSIO
N LINE

19. WHAT’S MORE?
ACTIVITY #5: LET’S TRY IT ON THE BOARD!
CYLINDER:
CUTTING
PLANE LINE
AND
SECTION
LINE

20. TECHNICAL DRAWING:
ALPHABET OF LINES
1. OBJECT OR VISIBLE LINES
2. CONSTRUCTION LINE
3. DIMENSION LINE
4. HIDDEN LINE
5. CENTRE LINE
6. EXTENSION LINE
7. CUTTING PLANE LINE
8. SHORT AND LONG BREAK LINES
9. LEADER LINE
10.PHANTOM LINE
11.SECTION LINE

21. WHAT HAVE I
LEARNED?
ACTIVITY # 8: LET’S CHECK YOUR
UNDERSTANDING
Post – Test.
Directions: Read each statement
carefully with understanding. Write the
letter of the correct answer before each
number.

22. LET’S REFLECT:
I UNDERSTAND THAT_______________________
I REALIZE THAT____________________________

23. THANK YOU