1. alphabet of lines

April 10, 2023 Engineering Drawing 1

Alphabet Of Lines


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.


3.1. 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.


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.


3.3. Ten Main Line Types

VisibleHiddenCenterDimensionExtensionLeaderSectionCutting Plane

PhantomBreak


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.


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.


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


4. Center Lines

Thin line consisting of long and short dashes.Shows the center of holes, slots, paths of rotation, and symmetrical objects.


5. Dimension Lines

Thin, dark lines. Show the length, width, and height of the features of an object. Terminated with arrowheads at the end.


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


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


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.


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.


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


Continued…

Short Break Line


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.


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.


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.


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


Relationship of Mating Parts

Phantom lines can also show how two or more parts go together without having to draw and dimension both parts.


Repeated Detail

Phantom lines can show repeated detail of an object.Saves the drafter time and the company money.Less chance of drafter error.


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.

1. alphabet of lines

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