engineering drawing ch-1

1. February 9, 2024 Engineering Drawing 1
Alphabet Of Lines

2. February 9, 2024 Engineering Drawing 2
Objectives:
At the end of this session you will
be able to:
- define a Line
- explain use of lines
- identify the ten main types of lines
- differentiate where the line types are
used
- produce the lines with various line
weights.

3. February 9, 2024 Engineering Drawing 3
3.1. Introduction to the
. Alphabet of Lines
In order to understand what the drafter is trying to get across, you
must be able to understand the symbols and lines he uses.
Each line has a definite form and line weight.
The standard thick line weight varies from 0.030 to 0.038 of an inch.
The standard thin line weight varies from 0.015 to 0.022 of an inch.
* For most engineering drawings you will require two thickness', a thick
and thin line. The general recommendation are that thick lines are
twice as thick as thin lines.

4. February 9, 2024 Engineering Drawing 4
3.2. What is line?
Definition:
- Line is the most basic design 'tool'.
- A line has length, width, tone, and texture.
- It may divide space, define a form, describe
contour, suggest direction.
Examples:
"A line is a dot that went for a walk." - Paul Klee.

5. February 9, 2024 Engineering Drawing 5
3.3. Ten Main Line Types
Visible
Hidden
Center
Dimension
Extension
Leader
Section
Cutting Plane
Phantom
Break

6. February 9, 2024 Engineering Drawing 6
1. Visible Lines
Dark, heavy lines with approximate
width 0.6mm.
Show the outline and shape of an
object.
Define features you can see in a
particular view.

7. February 9, 2024 Engineering Drawing 7
2. Hidden Lines
Light/medium, narrow, short dashed
lines with approximate width 0.3mm.
Shows the outline of a feature that can
not be seen in a particular view.
Used to help clarify a feature, but can
be omitted if they clutter a drawing.

8. February 9, 2024 Engineering Drawing 8
3. Section Lines
Thin lines usually drawn at a 45 degree
angle.
Indicate the material that has been cut
through in a sectional view.
Section
Line

9. February 9, 2024 Engineering Drawing 9
4. Center Lines
Thin line consisting of long and short
dashes.
Shows the center of holes, slots, paths
of rotation, and symmetrical objects.

10. February 9, 2024 Engineering Drawing 10
5. Dimension Lines
Thin, dark lines.
Show the length, width, and height of
the features of an object.
Terminated with arrowheads at the
end.

11. February 9, 2024 Engineering Drawing 11
6. Extension Lines
Thin line used to show the starting and
stopping points of a dimension.
Must have at least a 1mm space
between the object and the extension
line.
Extension Line
Dimension Line

12. February 9, 2024 Engineering Drawing 12
7. Leader Lines
Thin lines.
Used to show the dimension of a
feature or a note that is too large to be
placed beside the feature itself.
Leader Line

13. February 9, 2024 Engineering Drawing 13
8. Cutting Plane Lines
Thick broken line that is terminated
with short 90 degree arrowheads.
Shows where a part is mentally cut in
half to better see the interior detail.

14. February 9, 2024 Engineering Drawing 14
9. Break Lines
Used to break out sections for clarity or
for shortening a part.
Three types of break lines with different
line weights.
a. Short Breaks.
b. Long Breaks.
c. Cylindrical Breaks.

15. February 9, 2024 Engineering Drawing 15
Thick wavy line.
Used to break the edge or surface of a
part for clarity of a hidden surface.
Short Break Line
a. Short Break Lines

16. February 9, 2024 Engineering Drawing 16
Continued…
Short Break Line

17. February 9, 2024 Engineering Drawing 17
b. Long Break Lines
Long, thin lines.
Used to show that the middle section of
an object has been removed so it can
be drawn on a smaller piece of paper.

18. February 9, 2024 Engineering Drawing 18
c. Cylindrical Break Lines
Thin lines.
Used to show round parts that are
broken in half to better clarify the print
or to reduce the length of the object.

19. February 9, 2024 Engineering Drawing 19
10. Phantom Lines
Thin lines made up of long dashes alternating
with pairs of short dashes.
Three purposes in drawings.
1. To show the alternate position of
moving parts.
2. To show the relationship of parts
that fit together.
3. To show repeated detail.

20. February 9, 2024 Engineering Drawing 20
Alternate Position
Phantom lines can show where a part is
moving to and from.
Eliminates the confusion of thinking
there may be 2 parts instead of just 1.
Phantom Lines

21. February 9, 2024 Engineering Drawing 21
Relationship of Mating Parts
Phantom lines can also show how two
or more parts go together without
having to draw and dimension both
parts.

22. February 9, 2024 Engineering Drawing 22
Repeated Detail
Phantom lines can show repeated detail
of an object.
Saves the drafter time and the company
money.
Less chance of drafter error.

23. February 9, 2024 Engineering Drawing 23
3.4. Line Thickness
A thick continuous line is used for visible edges
and outlines.
A thin line is used for hatching, leader lines,
short centre lines, dimensions and projections.
Dashed lines are used to show important hidden
detail for example wall thickness and holes..
Thin chain lines are a common feature on
engineering drawings used to indicate centre
lines. Centre lines are used to identify the centre
of a circle, cylindrical features, or a line of
symmetry.

24. February 9, 2024 Engineering Drawing 24

25. February 9, 2024 Engineering Drawing 25