Drafting – Product Design & Architecture

Orthographic Projection

Alphabet of Lines

Object Line: Thick lines about .6mm(.032in) that show the visible edges of an object.

Hidden Line: Lines used to show interior detail that is not visible

from the outside of the part. Center Line: Lines that define the center of arcs, circles, or symmetrical parts.

They are half as thick as an object line.

Construction Line: Very lightly drawn lines used as guides to help draw

all other lines and shapes properly. Usually erased after being used.

Short Break Line: A freehanddrawn line that shows where a part is

broken to reveal detail behind the part or to shorten a long continuous part. (See

example of Long Break Lineon the next slide.)

Section Lines: Lines are used todefine where there is material

after a part of the object is cut away.

Alphabet of LinesCutting Plane Line: A line used to designate where a part has been cut

away to see detail. The arrows should point in the direction that you are

looking at the cutout.

Long Break Lines: Break lines are usedto either show detail or as in this case they can

be used to shorten very long objects thatdo not change in detail. Notice that this part

is 12” long however we have shortenedthe drawing with break lines to use

our space more efficiently.

Dimension Lines: Lines that are used toshow distance. Arrows are drawn on the

ends to show where the dimension line starts and ends. The actual distance is usually located in the middle of thisline to let you know the distance being communicated.

Dimension lines are used in conjunction with extension lines to properly

dimension objects.

Extension Lines: Lines used to show wherea dimension starts and stops on an object.

Used with dimension lines to properly dimensionan object. The line is 1/16” away from the

part as to not get confused with the object lines

Leader Lines: Leader lines are used toshow dimensions of arcs, circles and to help show detail. An arrow head is used to point

to the part you are dimensioning and the line comesoff the arrow point usually at a 45 degree angle.At the end of this line a horizontal line is drawn

with a note at the end telling information about what is being pointed at.How many lines from the

previous slide can you identify here?

Alphabet of linesPhantom Lines: Phantom lines are used

to identify alternate positions that a part my take up. In this example we are using Phantom

lines to show that the door handle may only move45 degrees from it’s horizontal

position.

How many lines from the previous 2 slides can you

identify here?

Orthographic (Multiview Drawings) Pictorial sketches are great for engineers to

explain ideas and communicate what the final part will look like to the customer. Unfortunately, pictorial drawings have some disadvantages. Foreshortened views and distorted features do not allow for accurate prototyping. Many times, for parts to be accurately depicted, you need straight on views of each surface.

Orthographic (Multiview Drawings) In order to obtain these straight line

views we have a type of drawing called Orthographic Projection also known as Multiview drawings. Orthographic projection is a way to project a view based on a line of sight that is perpendicular to that view. There are six of these views to any object as shown in the next slide.

Orthographic (Multiview Drawings)

ORTHO

The arrows represent the line of sight associated

with each view.

Use the button below to jumpbetween this

view and the orthoview on the next

page.

Orthographic Principal Views

ISO

Click to go backto ISO view.

Front, Top and Right views

are used most often. You can see how other views resemblethese three except they are not

as clear due to hidden lines.

Note how the viewsare oriented. Each view is

adjacent to the other asif they were unfolded

from a 3D shape.

Orthographic View Selection

Finding the best view of a part can be difficult. Two or more sides may look like the best solution for a front view. On the next slide is a list of characteristics that you should use in choosing your views.

Orthographic View Selection Steps in selecting the front.

Most natural position or use. Shows best shape and characteristic contours. Longest dimensions. Fewest hidden lines. Most stable and natural position. Relationship of other views

Most contours. Longest side. Least hidden lines. Best natural position.

Orthographic View Selection

Longest DimensionMost natural position.

No hidden lines.

Best shape description.

Orthographic View Selection Numbers

Another decision on view selection you need to make is how many views. You usually do not need more than three but you may only need one or two. The following slides will show when to make a decision between one, and two view drawings.

One View Selection

Uniform shape.

Two views will be identical

All dimensions easilyshown on one view.

One View Selection

It is also possible tohave one view drawingsof objects that are flat

and have even thickness.Gauges and gaskets aretwo such objects. We

have a gauge here on the left.

Two View Selection

Symmetrical parts. A third view would be identical to the other

views

Second view is necessary fordepth.

Precedence of Lines In multiple view drawings, many times different line

types will take up the same space, therefore, we have line precedence. The following is an explanation of which lines exist over others. Object lines over hidden and center. Hidden over center. Cutting plane lines over center lines.

The following slide will show an example.

Precedence of Lines

Object lines took precedence over the hidden lines you would see

from the hole. The center line in the top view would show the depth

of the hole as well as the right side view.

An object line here takes precedenceover the center line. However wedraw short thin lines beyond the

object to show there is a center lineunderneath the object line.

Do you want to be a good sketcher?

First Slide

Multiview Drawing

Another name for orthographic projection is multiview drawing

Involves visualization and implementation

Ability to see clearly in the mind’s eye an object

Process of drawing the object

Multiview Drawing

A system that allows you to make a two-dimensional drawing of a three-dimensional object

Viewing Objects

A box is formed by six mutually perpendicular planes of projection that are located around the object

Viewing Objects

Lines are formed on the planes by projecting the edges of the object onto the planes

These images are called “views”

There are six views formed by the planes of a box

Viewing Objects

Unfolding the box produces an arrangement of the six views

Angles of Projection

First-angle projection Used by many European countries Object is projected onto planes

from the first angle or quadrant Front view projected to vertical

plane Top view projected to horizontal

plane Left-side view projected to profile

plane

Angles of Projection

Third-angle projection Standard for the United States Third quadrant is used for

projection Front view projected to

vertical plane Top view projected to

horizontal plane Right-side view projected to

profile plane

Viewing Objects

Each view is placed in a constant location relative to the other views

Each view must be placed in its correct position

Views and features must be aligned

Choosing Views

Most commonly used views Front View Top View Right Side View

Most descriptive view is typically designated as the Front View

Choosing Views

Complex objects require three views to describe its shape

Simple objects can be described with two views Ex: Soda Can

Thin objects can be described with only one view Depth is given in a note Ex: Erasing Shield

Choosing the Views

Objects described in two views Third view would add nothing to the

description of the object Carefully select views to describe

shape of objects accurately

Curved Surfaces

Some curved surfaces do not show as curves in all views

CYLINDER

FRUSTRUM

CONE

WHEEL

HEIG

HT

WIDTH

DEPTH

Object Dimensions All objects have 3

dimensions Height

Distance from top to bottom

Width Distance from side

to side Depth

Distance from the front to back

TOP VI EW

FRONT VI EW R. SI DEVI EW

WI DTH

HEIG

HT

DEPTH

DEPT

H

Object Dimensions Front View

Shows width & height

Top View Shows width &

depth Side View

Shows height & depth

TOP VI EW

FRONT VI EWR. SI DE

Drawing Views of Objects

Depth can be projected between views by using a 45° miter line

FRONT VI EW

Line Types - Visible Edges that can be seen in a given view

areVisible or Object lines Visible lines are thick and dark

.028” or .7mm F or HB lead

TOP VI EW

Line Types - Hidden

Edges that cannot be seen from a given view are indicated by Hidden lines

Line Types - Hidden

Drawing hidden lines .125” (3mm) dashes .0625” (1mm) spaces between dashes Thin: .020” (.5mm) Dark: F or HB lead

.125"

.0625"

Line Types - Hidden

Follow rules for hidden line placement Alphabet of Lines

Drawings produced with CAD may violate hidden line rules

Line Types – Center

Center lines indicate axes of symmetry

Line Types – Center

Perpendicular lines for circular objects Small dashes cross at the center point of feature One center line drawn to indicate longitudinal

axis of cylinder or hole

Line Types - Center

.125"

.0625".75" - 1.5"

Draw center lines using a series of long and short dashes .125” (3mm) short dash @ the center .75”- 1.5” (20mm-40mm) long dash .0625” (1mm) spaces between dashes Thin: .02” (5mm)

Long dash extends .125” to .25” beyond feature

1.63 1.25

5.13

2.00

2.88

1.751.50

2.00

3.00

Ø2.22

TOP VI EW

FRONT VI EW R. SI DE VI EW

45°

SPECI AL CAM R. MI GLI ORATO 5/ 9/ 03 SCALE 1:1 16-52 12 NBHS

Placement of Views

Views should be visually balanced within the working space

Steps for Centering a Drawing

.75

.25

8.50

7.00

10.5011.00

.50

.25 .25

Draw border and title block using light construction lines

Draw diagonal lines from corners of border

Steps for Centering a Drawing

Add: Width 5.13 Space 1.50 Depth 2.00 Horizontal 8.63

Height 3.00 Space 1.50 Depth 2.00 Vertical 6.50

1.63 1.25

5.13

2.00

2.88

1.751.50

2.00

3.00

Ø2.22

TOP VI EW

FRONT VI EWR. SI DEVI EW

45°

4.3"

3"

4.3"

3"

Steps for Centering a Drawing

Draw a box the size of all views Measure from the center:

Half the width Half the height

FRONT VI EWR. SI DEVI EW

TOP VI EW

5.13 1.50 2.00

3.00

1.50

2.00

Steps for Centering a Drawing

Draw in views using light construction lines

TOP VI EW

FRONT VI EW R. SI DE VI EW

SPECI AL CAM R. MI GLI ORATO 5/ 9/ 03 SCALE 1:1 16-52 12 NBHS

Adding Details

Add holes and features

Transfer horizontal and vertical features

Use miter line to transfer depth

Multiview Drawing

Straight Edges

3

5

2

4

1A

B

6

Edges that are perpendicular to a plane of projection appear as a point

6

6

55

2

2

4

4

3

1

1

B

B A

A A

1 2

4

5 6

B

2 31

Straight Edges

Edges that are parallel to a plane of projection appear as lines

Edges that are inclined to a plane of projection appear as foreshortened lines

Curved Edges

Curved edges project as straight lines on the plane to which they are perpendicular

Curved edges project as curved lines on the planes to which they are parallel or inclined

Normal Surfaces

Normal surfaces appear as an edge in two opposite principal views, and appear a surface in all other principal views.

Inclined Surfaces

Inclined surfaces appear as an edge in two opposite principal views, and appear foreshortened (not true size) in all other principal views.

Oblique Surfaces

Oblique surfaces do not appear either as an edge or true size in any principal view.

Intersections & Tangencies

Where a curved surface is tangent to a plane surface, no line should be shown where they join

Intersections & Tangencies

Where a plane surface intersects a curved surface, an edge is formed

Intersections & Tangencies

Where the plane surface is horizontal or vertical, exceptions to these rules may occur