1

Multiview Scetching andProjection

Views of Surfaces(a) A plane surface that is perpendicular

to a plane of projection appears on edge as a straight line.

(b) If it is parallel to the plane of projection, it appears true size.

(c) If it is angled to the plane of projection, it appears foreshortened or smaller than its actual size.

A plane surface always projects either on edge or as a surface in any view. It can appear foreshortened, but can never appear larger than its true size in any view.

2

Views of Surfaces• Normal Surfaces

A normal surface is parallel to a planeof projection. It appears true size andtrue shape on the plane to which it is parallel, and as a vertical or a horizontal line on adjacent planes of projection.

• Inclined SurfacesAn inclined surface is perpendicular toone plane of projection, but inclined ortipped to adjacent planes.

Views of Surfaces

• Oblique SurfacesAn oblique surface is tipped to all principal planes of projection. It cannot appear true size in any standard view.An oblique surface always appears as a foreshortened surface in allthree standard views.

3

Views of Edges

• Normal EdgesA normal edge is a line that is perpendicular to a plane of projection.It appears as a point on that plane of projection and as a true-length linean adjacent planes.

Views of Edges

• Inclined EdgesAn inclined edge is parallel to one plane of projection but inclined toadjacent planes.It appears as a true-length line on the plane to which it is parallel and as a foreshortened line on adjacent planes.

4

Views of Edges• Oblique Edges

An oblique edge is tipped to all planes of projection.Since it is not perpendicular to any projection plane, it cannot appear as a point in anystandard view.Since it is not parallel to any projection plane, it cannot appear true length in any standardview.An oblique edge appears foreshortened and as an angled line in every view.

Views of AnglesIf an angle is in a normal plane, the angle will be

shown true size on the plane of projection towhich it is parallel.

If the angle is in an inclined plane, it may be porjected either larger orsmaller than the true angle, depending on its position.

45- degree angle is shown oversize in thefront view.

60- degree angle is shown undersize in bothviews.

5

Views of Parallel PlanesParalle lines in space will be projected as parallel lines in any

view unless they lie in the same plane and coincide toappear as a single line.

Views of a Point

A corner, or point, is the common intersection of three ormore surfaces. A point appears as a point in every view.

6

Meaning of LinesA straight visible or hidden line in a sketch has three possible meanings;

An edge (intersection) between two surfacesThe edge view of a surfaceThe limiting element of a curved surface

Adjacent ViewsWhile each area represents a surface at a different level, you can’t tellwhether A, B, or C is the highest surface or what shape the surfacesmay be until you see the other necessary views of the object.

7

Similar Shapes of SurfacesIf a flat surface is viewed from several different positions, each view will show the same number of sides and a similar shape.L-shaped surface appears L-shaped in every view in which it does not appear as a line.A T-shaped, U-shaped, or hexagonal surface will in each case have the same number of sides and vertices and the same characteristic shape whenever it appears as a surface.

Visualizing from Given Views

8

Reading a Drawing

Projecting a Third View

9

Hidden Line Practices

Hidden Line Practices

10

Hidden Line Practices

Hidden Line Practices

11

Sketching Centerlines

Sketching Centerlines

12

Cylindrical Surfaces

Space Curves

13

Intersections and Tangencies