## Projection symbols

First angle projection is widely used throughout all parts of Europe and often called European projection. Third angle in the system used in North America and alternatively described as American projection. In the British Isles, where industry works in co-operation with the rest of the world, both systems of projection are regularly in use. The current British and ISO standards state that both systems of projection are equally acceptable but they should never be mixed on

HP Projection

Fig. 4.6 VP is the vertical plane. HP is the horizontal plane. AVP the auxiliary vertical plane. GL is the ground line

Projector

HP Projection

Fig. 4.6 VP is the vertical plane. HP is the horizontal plane. AVP the auxiliary vertical plane. GL is the ground line

the same drawing. The projection symbol must be added to the completed drawing to indicate which system has been used.

Figure 4.8 shows the recommended proportions of the two projection symbols.

Figure 4.9 indicates how the First angle symbol was obtained from projections of a tapered roller. The Third angle alternative is given in Fig. 4.10.

Please note the movement suggested by the arrow in Fig. 4.9, Fig. 4.10 and also in Fig. 4.8, since orientation is the main clue to understanding the fundamental differences in projection systems.

An experienced draughtsman must be fully conversant with all forms of orthographic and pictorial projection and be able to produce a drawing where no doubt or ambiguity relating to its interpretation can exist.

 D ,____ ft VI

Drawing paper

Drawing paper

Drawing procedure drawing sheet so that the spaces between the three drawings are roughly the same.

Stage 2 (Fig. 4.12). In each view, mark out the main centre-lines. Position any complete circles, in any view, and line them in from the start, if possible. Here complete circles exist only in the plan view. The heights of the cylindrical features are now measured in the front view and are projected over to the end view.

Stage 3 (Fig. 4.13). Complete the plan view and project up into the front view the sides of the cylindrical parts.

Stage 4 (Fig. 4.14). Complete the front and end views. Add dimensions, and check that the drawing (mental check) can be redrawn from the dimensions given; otherwise the dimensioning is incomplete. Add the title and any necessary notes.

It is generally advisable to mark out the same feature in as many views as is possible at the same time. Not only is this practice time-saving, but a continuous check on the correct projection between each view is possible, as the draughtsman then tends naturally to think in the three dimensions of length, breadth and depth. It is rarely advantageous to complete one view before starting the others.

Generally, industrial draughtsmen do not complete one view on a drawing before starting the next, but rather work on all views together. While projecting features between views, a certain amount of mental checking takes place regarding shape and form, and this assists accuracy. The following series of drawings shows stages in producing a typical working drawing in first angle projection.

Stage 1 (Fig. 4.11). Estimate the space required for each of the views from the overall dimensions in each plane, and position the views on the available

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### Responses

• suck
can give detailed dimension or not? XP
9 years ago
• Ghenet
Which view is standard in an orthographic drawing?
9 years ago
• LUCIA
How to drawing angle projection symbol?
7 years ago
• Tom Propst
How to draw symbols cad projections?
7 years ago
• liya
How to draw the projection symbol accurately?
3 years ago
• ali
What is projection system symbol?
3 years ago
• Zahra
What method be used to indicate the system of projection in engineering drawing?
3 years ago
• carita
Why projection symbol is achieved in landscape view?
2 years ago
• eden
How to draw a projection symbol engineering drawing?
2 years ago
• katrin
How to constract a projection symbol step by step?
2 years ago
• sarama
What is known as projection symbols?
2 years ago
• Kaarina
What are the symbols used in projection methods in engineering graphics ?
2 years ago
• Eveliina
How to the symbol for the projectio system used?
2 years ago
• maryam
What are the dimensions for the symbol of projection?
2 years ago
• REN
What is a projectin symbol?
1 year ago
• hagos
What type of projection is indicated by the following symbol?
1 year ago
• Maxima
What forms the basis of the projection symbols used in drafting?
1 year ago
• luca
What angle of projection is used in north america?
1 year ago
• fedele romani
Why is the projection symbol important on an engineering drawing?
1 year ago
• Zewdi
What are projection symbols in drawing?
1 year ago
• Brodie
Does structural drawing use angle projection symbol?
1 year ago
• JAMIE WALLACE
What is the use of sympol in orthographic projection?
1 year ago
• asmait
How large should a third projection symbol be?
1 year ago
• BEATRICE
HOW TO DRAW THE PROJETION SYMBOL?
12 months ago
• WILLIAM
How to draw projection symbol in solidworks?
12 months ago
• david
What is the graphics projection symbel called?
11 months ago
• Aziza
How many types of projection symbols?
11 months ago
• senay tesfalem
What are projection symbols in egineering drawings?
10 months ago
• artemia
How to add orthographic projection symbol fusion?
10 months ago
• loredana
Why are prokjection symbols used?
9 months ago
• barry
What are the dimensions for the third angle projection symbol?
9 months ago
• luigia
Why must symbols be clear and distinct in an engineering drawing?
9 months ago
• Armida
WHAT STANDARD IS ARROW PROJECTION FOR DRAWINGS?
8 months ago
• CORA
What is the angle symbol on an engineering drawing?
8 months ago
• lukas hueber
What is the meanuing of projection symbol in drawing sheet?
7 months ago
• MINNA
What does the angle projection symbol represent?
6 months ago
• marilyn
How to get the third angle projection symbol in solidworks drawing?
6 months ago
• odovacar
What is the shape indicating third angle projection?
5 months ago
• fabrizio fiorentini
What does the angle notation mean in a drawing?
4 months ago
• jasmine
HOW MANY PROJECTION VIEWS SYMBOLS ARE THERE FOR ENGINEERING DRAWINGS?
3 months ago
• Kieron
What is the symbol and abbreviation for drawing projection?
1 month ago
• amethyst
Where does the third angle projection symbol go on an orthographic drawing?
16 days ago
• zahra
What does the projection sign on a techniqaual drawing show?
12 days ago
• J
What is 2 form type of orthographic projection the symbbol for both?
7 days ago