Chapter 08 orthographic convention

EXAMPLE : Already met convention practice Front view CONVENTION PRACTICE... Incompleted view TYPES OF CONVENTION PRACTICE 2.1 Incompleted side view 2.4 Local view 2.3 Half view 2.2 Parti

Chapter 8

Convention Practice

in Orthographic

Writing

Convention is a commonly accepted practices

which disregard some strict rules of orthographic projection

Multiview representation

Convention practices

Disregard some rules

Using a dash line for

representing the hidden edge.

EXAMPLE : Already met convention practice

Front view

CONVENTION PRACTICE

To improve the clarity of a drawing

To reduce the drafting effort.

To save or efficiently use a drawing space.

To facilitate the dimensioning.

1 Alternate position of side view

2 Incompleted view

TYPES OF CONVENTION PRACTICE

2.1 Incompleted side view

2.4 Local view

2.3 Half view

2.2 Partial view

3 Aligned view

4 Enlarged view

6 Intersection : Hole on a cylinder

5 Non-existing intersection line

TYPES OF CONVENTION PRACTICE

ALTERNATE POSITION OF

SIDE VIEW

Whenever the height of an object is small and the depth is relatively large, places the side view besidethe top view.

To save drawing space

To improve the clarity of a drawing

Purposes

Conventional practice

ALTERNATE POSITION OF SIDE VIEW

Top

Right

Example

Slot becomes more readable.

Hole becomes more readable.

New orientation of views still agree with 3 rd angle system.

INCOMPLETED SIDE VIEW

Incompleted side views are side views that

are eliminated a feature that can not clearlyseen from a selected viewing direction

DEFINITION

Principal view

Difficult to read and to dimension.

Details are interfered by those

on the opposite view.

Example : Strictly orthographic projection

Example : Incompleted side views

Principal view

Example : Incompleted side views representation

PARTIAL VIEW

HALF VIEW LOCAL VIEW

Partial view is a view that represents portions

of the part that have a features need to clarify.

Clearly seen

a shape.

Example : Partial views

Symmetry symbol

Left half Right half

Thin line (4H)

Center line acts as a line of symmetry.

No continuous line !

Example : Half view

Half view can be made by drawing the viewsslightly beyond the line of symmetry.

omit the break line.

Example : Half view : alternative representation

Thin line (4H)

Example : Half view : two symmetry axes

Example : Local view

Shape of the slot is completely shown.

R6

Easy for dimensioning

ALIGNED VIEW

Example : Necessity of align view

Waste of time Confuse

Apply convention

Clear

Strictly Projection

CONVENTION PRACTICE

For an object that has symmetrical positioned

features, it is advisable to show them on adjacentview in true size at true radial distance from

the symmetry axis

Example : Align view of holes

Gives the impression that there

is a hole at the center of the plate.

Given

Apply aligned convention

Example : Align view of holes

Given

Gives the impression that holes are at unsymmetrical position.

Apply aligned convention

Example : Align view of holes

Apply aligned convention

Example :

Example : Align view of ribs

Apply aligned convention

Example : Align view of ribs & holes

Apply aligned convention

Example : Align view of ribs & holes & keyway

Make Orthographic Projection

Apply Convention

Example : Align view

ENLARGED VIEW

Enlarged view is a view partly selected from

full view and is drawn with a larger scale.

Example : Enlarged view

Scale

NON-EXISTING LINE OF

INTERSECTION

Non-existing line of intersection is the line of

intersecting surfaces that are eliminated by filletsand rounds

When true projection mislead the representation

of an object, it is necessary to show the additionallines that are projected from the actual intersection

of the surfaces as if the fillets and rounds were

not present

DEFINITION

Conventional practice

Example : Non-existing line of intersection

Object does not has

rounds and fillets

Edges of the surfaces

are shown as lines in

the top view.

Example : Non-existing line of intersection

The view looks like a plate with a hole !!

Object has

rounds and fillets

No edge ! (No intersection between surfaces)

Convention practice required ! Construct a non-existing line of intersection.

Example : Non-existing line of intersection

INTERSECTION BETWEEN

FILLET AND ROUND

Runout

INTERSECTION BETWEEN

FILLET AND ROUND

Tangent point

TO DRAW A RUNOUT

about 1/8 of circle

R R/3

R = radius of fillet or round

R

INTERSECTION BETWEEN ROUND PLANE SURFACE

INTERSECTION

HOLE IN CYLINDER

HOLE IN CYLINDER