multi-view drawing chapter 5 - los rios community...

Multi-View Drawing 1

Multi-View Drawing Chapter 5

Engineering Design TechnologySacramento City College

2 Multi-View Drawing

Objectives Identify and select the various views of an

object.Determine the number of views needed to

describe fully the shape and size of an object.

Define the term orthographic projectionDescribe the difference between first and

third-angle projection.


ObjectivesVisualize the “glass box” concept and apply

it to the process of selecting and locating views on a drawing.


ObjectivesDevelop a multi-view drawing, following a

prescribed step-by-step process, from the initial idea to a finished drawing.


VocabularyFirst angle

projectionFront ViewHorizontal PlaneImplementationMulti-view

DrawingNegative CylinderNormal ViewsOrthographic

ProjectionPictorial Drawing

Profile planeQuadrantRight-side ViewSolid ModelSpherical Third-angle

ProjectionTop ViewVertical PlaneVisualization


CommunicationPeople communicate by verbal and written

language and graphic (pictorial) means.

Technical drawings are a graphical meansto communicate.

When accurate visual understanding is necessary, technical drawing is the most exact method that can be used.


Visualization and ImplementationTechnical drawing involves:Visualization

The ability to see clearly in the mind’s eye what a machine, device or object looks like.

ImplementationThe process of drawing the object that

has been visualized.


Visualization and ImplementationA technical drawing, properly made, gives a

clearer, more accurate description of an object than a photograph or written explanation.


Visualization and ImplementationTechnical drawings made according to

standard rules result in views that give an exact visual description of an object.

The multi-view drawing is the major type of drawing used in the industry.


Multi-View Drawing A photograph can show three viewsFront.Top.Right Side.

Nearly all objects have six sides, not three.


Multi-View Drawing


Multi-View Drawing If an object could be shown in a single

photograph, it would also include A left-side view.A rear view.A bottom view.


Pictorial Drawing An object cannot be photographed if it has

not been built (!)

This limits the usefulness of photographs to “show what an object looks like” (!)


Pictorial DrawingA pictorial drawingIs a drawing.Shows an object as it would appear in

a photograph.Shows the way an object looks, in

general.It does not show, the exact forms and

relationships of the parts that make up the object.


Pictorial DrawingA pictorial drawingShows the object as it appears, not

as it really is.Holes in the base appear as ellipses,

not as true circles.


Pictorial Drawing

Pictorial Drawing

Photograph


Multi-View DrawingThe goal, is to represent an object on a

sheet of paper in a way that described its exact shape and proportions.

To do this: Draw views of the object as it is seen from different positions.


Multi-View Drawing These views are then arranged in a

standard order.

Anyone familiar with drafting practices can understand them immediately.


Multi-View DrawingTo describe accurately the shape of each

view imagine a position Directly in front of the object.Directly above the object.On the right side of the object.


Multi-View DrawingThe front, top and right side views are the

ones most often used to describe an object in technical drawing.

They are called the Normal views.


The Relationship of ViewsViews must be placed in proper

relationship to each other.The Top View is directly above the

Front ViewThe Right-side View is directly to the

right of the Front View.


The Relationship of ViewsWhen the views are placed in proper

relationship to one another, the result is a multi-view drawing.

Multi-view drawing is the exact representation of an object on one plane.


The Relationship of ViewsOther views may also be required.The proper relationship of the six views is

shown below

Top View

Bottom View

Front ViewLeft-sideView

RearView

Right-sideView

“Normal views”


V-Block


Orthographic ProjectionThese views are developed through the

principles of orthographic projectionOrtho - “straight” or “at right angles”.Graphic - “written” or “drawn”.Projection - from two Latin words:

Pro, meaning “forward”Jacere, meaning “to throw”

The literal meaning is “thrown forward, drawn at right angles”.


Orthographic ProjectionDefinition: Orthographic projection is:the method of representing the exact

form of an object in two or more viewson planes usually at right angles to

each other, by lines drawn perpendicular from the

object to the planes.


Orthographic ProjectionAn orthographic projection drawing is a

representation of the separate views of an object on a two-dimensional surface.

It reveals the width, depth and height of an object.


Orthographic Projection


Angles of Projection


Angles of ProjectionOn a technical drawing, a plane is an

imaginary flat surface that has no thickness.

Orthographic projection involves the use of three planes.Vertical plane.Horizontal plane.Profile plane.

A view of an object is projected and drawn on each plane.


Angles of Projection The vertical and

horizontal planes divide space into four quadrants (quarters of a circle).

In orthographic projection, quadrants are usually called angles.

Thus we get the names, first-angle projectionand third angle projection


Angles of ProjectionFirst angle projectionis used in European countries.

Third angle projectionis used in the US and Canada.

Second and fourth angle projectionis not used in any country.


First-Angle ProjectionFirst-angle projectionFront view = vertical plane.Top view = horizontal plane.Left side view = profile plane.


First-Angle Projection In first angle projection, the Front View is located above the

Top View.The Left-side View is to the right of

the Front View.Refer to Figure 5-12.


First-Angle Projection In first-angle projection, the projection plane is on the far side

of the object from the viewer.

The views of the object are projected to the rear and onto the projection plane instead of being projected forward.


First-Angle ProjectionFirst-angle projection

Front view = projected to vertical plane.Top view = projected to horizontal plane.Left side view = projected to profile plane.

First angleThird angle


Third-Angle ProjectionThird-angle projection

Front view = projected to vertical plane.Top view = projected to horizontal plane.Right side view = projected to profile plane.

First angleThird angle


Third-Angle Projection In third-angle projectionthe Top View is located above the

Front View.The Right-Side View is to the right of

the Front View.Refer to Figure 5-14.


Third-Angle ProjectionThe views appear in their natural positions.The Top View appears above the

front view.The Right-Side View is to the right of

the Front View.The Left-Side View is to the left of the

front view.


The Glass Box


The Glass Box In each case, the three views have been

developed by using imaginary transparent planes.The views are projected onto these

planes.


The Glass Box Visualize a glass box around the object

Project the view of the object onto a side of the box.

“Unfold the box” to one plane.

The views will be in their relative positions.


The Glass Box


Projection of Lines


Projection of LinesThere are four kinds of straight lines found

on objects in drawingsHorizontal.Vertical.Inclined.Oblique.

Each line is projected by locating its endpoint.


Horizontal LinesHorizontal linesAre parallel to the frontal plane.Are parallel to the top plane.Are perpendicular to the profile plane.

(right-side view)(Parallel to 2; perpendicular to 1)

Appear as true length in twoFrontal and Top planes.

Appear as a point in the third.Right-side plane


Vertical LinesVertical LinesAre parallel to the frontal plane.Are parallel to the profile plane.Are perpendicular to the horizontal

plane.(Parallel to 2; perpendicular to 1)

Appear true length in two planes:Frontal and Profile planes.

Appear as a point in the third:Horizontal plane.


Inclined Lines Inclined LinesAre parallel to one plane of

projection.Are inclined in the other two planes.

(Parallel to only 1; shortened in 2)

Appear true length in one of the planes.

Appear shortened in the other twoplanes.


Oblique LinesOblique LinesAre neither parallel nor perpendicular

to any of the planes or projections (!)

Appear shortened in all three planesof projection.

Can only be drawn by locating and connecting line endpoints.


Curved LinesCurved Lines may beCircular.Elliptical.Parabolic.Hyperbolic.Some other geometric curve form.

They may also be irregular curves.


Projection of SurfacesSurfaces may be Horizontal.Vertical.Inclined.Oblique.Curved.

They are drawn by locating the end points of the lines that outline their shape.


Horizontal SurfacesHorizontal surfacesAre parallel to the horizontal

projection plane Appear true size and shape in the

Top View.


Vertical SurfacesVertical surfacesAre parallel to one or the other of the

frontal or profile planes, and Appear in their true size and shape in

the Front View or the Right-side View.

They are perpendicular to the other two planes and appear as lines in these planes


Inclined Surfaces Inclined surfacesAre neither horizontal nor verticalAre perpendicular to one of the

projection planes and appear as a true length line in this view.


Oblique SurfacesOblique SurfacesAre neither parallel nor perpendicular

to any of the planes of projection.

They appear as a surface in all views but not in their true size and shape.


Curved Surfaces


Curved SurfacesMay be a single curved surface (cone or

cylinder)a double curved surface (sphere,

spheroid or torusa warped surface


Curved SurfacesAppear as circles in one view and as

rectangles in the other view


Techniques for Special Lines and Surfaces



To describe an object fully, show every feature in every view, whether or not it can ordinarily be seen

Also include other lines that are not part of the object to clarify relationships and positions in the drawing



Special line symbols are used to differentiate between object lines and lines that have other special meanings


Hidden Lines


Hidden LinesBoth interior and exterior features are

projected in the same way.


Hidden LinesParts that cannot be seen in the views are

drawn with hidden lines.

Hidden lines are made up of short dashes.


Hidden LinesThe first line of a hidden line touches the

line where it starts.Refer to Figure 5-18A.


Hidden Lines If a hidden line is a continuation of a visible

line, space is left between the visible line and the first dash of the hidden line.Refer to Figure 5-18B.


Hidden Lines If the hidden lines show corners, the

dashes touch the corners.Refer to Figure 5-18C.


Hidden LinesDashes for hidden arcs start and end at the

tangent points.Refer to Figure 5-19A.


Hidden LinesWhen a hidden arc is tangent to a visible

line, leave a space.Refer to Figure 5-19B.


Hidden LinesWhen a hidden line and a visible line

project at the same place, show the visible line.Refer to Figure 5-19C.


Hidden LinesWhen a centerline and a hidden line

project at the same place, draw the hidden line.Refer to Figure 5-20A.


Hidden LinesWhen a hidden line crosses a visible line,

do not cross the visible line with a dash.Refer to Figure 5-20B.


Hidden LinesWhen hidden lines cross, the nearest

hidden line has the “right of way”Draw the nearest hidden line through

a space in the farther hidden line.


Centerlines


CenterlinesCenterlines are special lines used to locate

views and dimensions.


CenterlinesPrimary centerlinesLocate the center on symmetrical

views in which one part is a mirror image of another.

Are used as major locating lines to help in making the views.

They are also used as base lines for dimensioning.

Are drawn first.


CenterlinesSecondary centerlines are used for drawing

details of a part


Precedence of Lines


Precedence of LinesThe following priority of lines exists:

1. Visible lines.2. Hidden lines.3. Cutting-plane lines.4. Center lines.5. Break lines.6. Dimension and extension lines.7. Section lines (crosshatching).


Curved Surfaces


Curved SurfacesSome curved surfaces, such as cylinders

and cones do not show curved surfaces in all views.


Curved SurfacesA cylinder with its axis perpendicular to a

plane will show as a circle on that plane and as a rectangle on the other two planes.


Curved SurfacesThe holes may be thought of as negative

cylindersIn mathematics, negative means an

amount less than zero.A hole is a “nothing” cylinder, but it

does have size.


ConesA cone appears as a circle in one view. It appears as a triangle in the other view.


ConesOne view of a frustum of a cone appears as

two circlesIn the top view, the conical surface is

represented by the space between the two circles.


ConesCylinders, cones and frustums of cones

have single curved surfaces.The appear as circles in one view and

straight lines in another.


Deciding Which Views To Draw


Deciding Which View to DrawSix views are not needed to describe most

objects.

Usually three views are sufficient.


Deciding Which View to DrawMost pieces can be recognized because

they have a characteristic view.

This is the first view to consider, and usually is the first view to draw.

Next, consider the normal position of the part when it is in use.


Deciding Which View to DrawViews with the fewest hidden lines are

easiest to read, and require less time to draw.


Deciding Which View to DrawThe main purpose of drawing views is to

describe the shape of the object.

It is a waste of time to make more views than are necessary to describe the object.


Deciding Which View to DrawSome parts can be described in only one

view.Figure 5-23 A.Sheet material: plywoodParts of uniform thickness

The thickness can be given in a note.


Deciding Which View to Draw


Deciding Which View to DrawSome parts can be described in only one

view.Compare 5-24 C and D.


Deciding Which View to DrawSome parts can be described in two views.Figure 5-25 A, B, C, D, E.


Deciding Which View to DrawExamples of parts that can be drawn in two

views: Figure 5-26 A - F.


Deciding Which View to DrawLong and narrow objects may suggest top

and front view.

Short and broad objects may suggest top and right-side views.

Right side is preferred over left-side when a choices is available.

Top view is preferred over bottom viewwhen a choice is available.


Placing Views


Placing ViewsThe size of the drawing sheet should allow

enough space for the number of views needed to give a clear description of the part.

The method for determining the positions of the views is the same for any space.


Placing ViewsThe “working space” of a drawing is the

area inside the border.

Objects are never drawn directly touching the border.

Objects are drawn so there is a spacebetween the object and the border line.Refer to Figure 5-28.


Placing Views 1. Measure the available drawing area using the scale of

the drawing.

2. Subtract out the space occupied by the object Horizontal: Vertical:

Front View Front View Right side View Top View

3. Divide the remaining area by 4 Put one part each

On left of Front View On right of Front View

On left of Right Side View On right of Right Side View


Placing ViewsConverting decimals to fractions.1. Use page 699 in textLook up decimalLook to left to find equivalent fraction

2. Convert fractions to 12ths of an inch0.38 = 3/83/8 = x/128x = 36x = 4.5 /12


Figure 5-28


Figure 5-29


Placing Views1. Add the width and the depth of the

object.


Placing Views1. Add the width and the depth of the

object.For the Base, Fig 5-63, p152, The width is: 7.50”The height is: 2.25” + 1.62”The depth is: 3.25”

Width + depth = 7.50 + 3.25 = 10.75


Placing Views2. Subtract this total from the width of the

drawing space.Refer to Figure 5-30.A space of about 1” is commonly left

between the Side View and the Front View.

Space may be larger or smaller, depending upon the shapes of the views.


Figure 5-30


Placing Views2. Subtract this total from the width of the

drawing space.For the Base, Fig 5-63, p152, Drawing Space width = 11” - 0.25” - 0.25” = 10.5” max.

Width + depth = 7.50 + 3.25 = 10.75


Placing Views3. Add the height and the depth of the

object.

4. Subtract this total from the height of the drawing space.

5. Divide the remaining space evenly.


Figure 5-30


Locating and Transferring Measurements


Locating MeasurementsMeasurements made on one view can be

transferred to another.This process also insures accuracy.Refer to Figure 5-33.


Locating Measurements1. Draw upward from the Front view to

locate width measurements in the Top viewDraw downward from the top view to

locate width measurements on the Front view.


Locating Measurements2. Draw a light line across to the Side view

from the Front view to locate height measurementsUse a similar method to project height

measurements from the side view to the front view


Locating MeasurementsHeight of Front view - transfer to Right-side

view.

Depth measurements show as verticaldistances in the Top view and as horizontal distances in the the Right-side view.


Locating Measurements


Locating Measurements3. Depth measurements show as Vertical distances - Top view Horizontal distances - Right-side view

To transfer these measurements useArcs45o triangleDividersScale


Using Arcs to Transfer


Using Scale to Transfer


Using 45 Line to Transfer


Summary of StepsFollow a step-by-step method to insure

accuracyCarry all views along togetherDo not attempt to finish one view before

starting the othersUse a hard lead pencil (4H or 6H) and light,

thin lines for preliminary (layout) linesUse F, HB or H for final lines


Summary of Steps1. Consider the Characteristic View first.2. Determine the number of views.3. Locate the views.4. Block in the views with light, thin layout

lines.5. Lay off the principal measurements.


Summary of Steps6. Draw the principal lines.7. Lay off the measurements for details such

as centers for arcs, circles and ribs.8. Draw the circles and arcs.9. Draw any additional lines needed to

complete views.


Summary of Steps10. Darken the lines where necessary to

make them sharp and black and of proper thickness

multi-view drawing chapter 5 - los rios community...

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