Projection rules

Projection rule 2

Distance between two points of a feature in related views must be equal

Projection rule 1

Every point of feature in one view much be aligned on a parallel projector in any adjacent view

A

A

B

B

Projection rule 3

Features are foreshortened when the line of sight are not perpendicular to the feature

Projection rule 4

Features are true length or true size when the line of sight are perpendicular to the feature

Normal surface

True size and true shape

edgeedge

Application of Projection Rule 3 and 4

Foreshortened shape

Foreshortened shapeEdge, true size

Inclined surface

Application of Projection Rule 3 and 4

Oblique surface : •As an area in three views•None of it is in true size

Surface B is an oblique surface

Application of Projection Rule 3 and 4

Surface C

Projection rule 5

Area that are the same feature will always be similar in configuration from one view to the next, unless viewed from on edge.

Similar areas:Oblique surface

Application of Projection rule 5

Similar areas:Inclined surface

Application of Projection rule 5

Surface G and F

Projection rule 6

Parallel features will always parallel in all views.

Front view: Surface1-2(vertical), G, F

Projection rule 7

Surfaces that are parallel to the line of sight will appear on edge and represented as line.

Surface B and C, B and G, A and B

Projection rule 8

No two contiguous surfaces lie in the same plane

Adjacent areas

Application of Projection rule 8

Vertex labeling

Surface labeling

In-class activity: Surface labeling

In-class activity Missing line problem 1

In-class activity Missing line problem 2

In-class activity Missing view problem 1

In-class activity Missing view problem 2

More missing line, missing view problems

Homework: Textbook page 289 Problem 5.3( missing view problems)Problem 5.4 (missing line problems)

Do not hand in, self-practice only