112 PROJECTIONS DEF a projection is a representation of a threedimensional shape on a twodimensional surface PROJECTIONS Projections are arranged into 3 categories multiview Isometric ID: 614324
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Slide1
PROJECTIONS
11.2Slide2
PROJECTIONS
DEF:
a projection is a representation of a three-dimensional shape on a two-dimensional surface.Slide3
PROJECTIONS
Projections are arranged into 3 categories:
multi-view
Isometric
oblique
An example of an
isometric
projectionSlide4
DRAWING TERMINOLOGY
OBSERVATORY
p., 343Slide5Slide6
PROJECTIONS DIFFER IN 2 ASPECTS:
DIFFERENCE #1
Position of the object with respect to the surface it is drawn on.
DIFFERENCE #2
Angle between the visual rays & the sheet of paper.
The
table on the next slide will illustrate these differences.Slide7
COMMON TYPES OF PROJECTIONS
OBSERVATORY p., 344Slide8Slide9
ORTHOGONAL PROJECTIONS
DEF:
an orthogonal projection is a projection in which the visual rays are perpendicular from the surface of the paper.Slide10
PROJECTIONSSlide11
ISOMETRIC vs. OBLIQUE
ISOMETRIC
OBLIQUESlide12
ISOMETRIC PROJECTIONS
DEF:
an isometric projection is a “perspective” drawing of an object where the principal edges are arranged on 3 isometric angles (120
o
degrees).Slide13
ISOMETRIC PROJECTIONS
OBSERVATORY p., 347
OBSERVATORY p., 347Slide14
2
0
20
50
10
8
14
28
3
5
We will illustrate the main stages of isometric drawing of the object shown above in multi-view.
We will use a method called box construction.
To create the box, use construction lines to outline an isometric box as large as the overall object to be drawn.
The vertical axis is equal to the real height.
The two other axes, drawn at 30° to horizontal, correspond to the actual width and length of the object.
Isometric drawingSlide15
Isometric drawing
The object is drawn by removing volumes from the box.
A 30º- 60º set square is used to trace the isometric lines.
The box is an isometric drawing as large as the overall object to be shown. Its lines are drawn very faintly.
Measurements are reported on the isometric axes, or on lines parallel to these axes.Slide16
Isometric drawing
The object is drawn by removing volumes from the box.
A 30º- 60º set square is used to trace the isometric lines.
The box is an isometric drawing as large as the overall object to be shown. Its lines are drawn very faintly.
Measurements are reported on the isometric axes, or on lines parallel to these axes.Slide17
Isometric drawing
STAGE 1
STAGE 2
STAGE 3
Sketch the box.
STAGES OF DRAWING IN ISOMETRIC PERSPECTIVE
Measure on the axes
and trace the details in construction lines.
Carry out the final layout. Slide18
Isometric drawing
STAGE
1
STAGE
2
STAGE
3
Sketch the box.
STAGES OF DRAWING IN ISOMETRIC PERSPECTIVE
Measure on the axes and trace the details in construction lines.
Carry out the final layout. Slide19
MULTI-VIEW PROJECTIONS
DEF:
a multi-view projection is a 2-D representation of the different views on an object.Slide20
MULTI-VIEW PROJECTIONS
OBSERVATORY P., 345Slide21
MULTI-VIEW PROJECTIONS
OBSERVATORY P., 346Slide22Slide23
Try it yourself!
Begin working on the lab entitled projections.
Answer all
questions
on pages 1-2 and complete the
multi-view projection. Slide24
PERSEPCTIVE
Drawings with “perspective” represent all 3 dimensions in a single view.Slide25
OBLIQUE PROJECTIONS
DEF:
a perspective drawing in which one of the sides of the object is parallel to the paper, but the depth is represented by parallel lines drawn at oblique angles.Slide26
THE USE OF PROJECTIONS IN ENGINEERING DRAWINGS
3 main drawings used in an engineering projects are:
General
Exploded views
Detail DrawingsSlide27
GENERAL DRAWINGS
An engineering drawing that shows the overall design of an object.
OBSERVATORY p., 349Slide28
EXPLODED-VIEW DRAWINGS
An engineering drawing that shows the different parts, or features, of the object separately.
OBSERVATORY p., 349Slide29
DETAIL DRAWINGS
An engineering drawing that specifies all of the details necessary to make a particular part of an object.Slide30
TYPES OF ENGINEERING DRAWINGS
TYPE
DESCRIPTION
PROJECTION
General
A drawing
which shows the
overall
appearance of an object.
Multi-view
Isometric
Exploded
A drawing that illustrates the
different parts
of an object,
separately.
May include a list of materials.
Isometric
Detail
A drawing that contains
all
of the necessary
elements
to
construct
an object.
Multi-view