Multiview SketchesMultiview Sketches

Engineering GraphicsEngineering Graphics

Stephen W. Crown Ph.D.Stephen W. Crown Ph.D.

ObjectiveObjective

How to use sketching as an effective How to use sketching as an effective tool in the engineering design processtool in the engineering design process

How to represent a 3-D object How to represent a 3-D object effectively on a 2-D drawing surface effectively on a 2-D drawing surface (multiview sketching)(multiview sketching)

OverviewOverview

SketchingSketching• DefinitionDefinition• Tools / InstrumentsTools / Instruments

Mechanics of sketchingMechanics of sketching• Lines and CurvesLines and Curves• A Bounding BoxA Bounding Box

Multiview sketchesMultiview sketches• How to create themHow to create them• When to use themWhen to use them

Why use sketches?Why use sketches?• CreativityCreativity• CommunicationCommunication• DocumentationDocumentation

SketchingSketching Definition: A rough freehand drawing Definition: A rough freehand drawing

used to document, communicate, and used to document, communicate, and refine ideas developed in the ideation refine ideas developed in the ideation phase of the design processphase of the design process

Beginners will benefit from instrumentsBeginners will benefit from instruments Follows standard practices Follows standard practices A developed skillA developed skill Should be the first step of Should be the first step of

any CAD drawing any CAD drawing

Tools Tools PencilsPencils

• Use a mechanical pencil (0.5mm lead)Use a mechanical pencil (0.5mm lead)• Practice using different pressure to produce desired Practice using different pressure to produce desired

linetypes (construction lines)linetypes (construction lines)

PaperPaper• Unlined paper is the most usefulUnlined paper is the most useful• Square grid and tracing paper is often usefulSquare grid and tracing paper is often useful

EraserEraser• A good eraser is worth the investmentA good eraser is worth the investment• Do not overuse your eraser (save some mistakes)Do not overuse your eraser (save some mistakes)

Using Simple InstrumentsUsing Simple Instruments The use of mechanical instruments is The use of mechanical instruments is

recommended only for beginners. Break away recommended only for beginners. Break away from reliance on tools that slow you down.from reliance on tools that slow you down.

Helpful tools for beginnersHelpful tools for beginners• CompassCompass• TrianglesTriangles• DividersDividers• RulerRuler

Mechanics of SketchingMechanics of Sketching

Drawing straight Drawing straight lineslines

Drawing curved Drawing curved lineslines

Using a bounding Using a bounding boxbox

Drawing straight linesDrawing straight lines

Mark starting and ending pointMark starting and ending point Break long lines into short line Break long lines into short line

segments by marking the midpointsegments by marking the midpoint Start with a light pass if necessary Start with a light pass if necessary

and then darkenand then darken Use a loose comfortable gripUse a loose comfortable grip Reorient the paper to your Reorient the paper to your

convenienceconvenience• test your skill with different orientationstest your skill with different orientations

• an awkward orientation may an awkward orientation may occasionally produce positive resultsoccasionally produce positive results

Drawing curved linesDrawing curved lines

Break large arcs/circles into small Break large arcs/circles into small segmentssegments

Make guide marks for each Make guide marks for each segmentsegment

Circles and EllipsesCircles and Ellipses• Sketch a light square/rectangleSketch a light square/rectangle• Lightly sketch in diagonalsLightly sketch in diagonals• Mark contact points on Mark contact points on

square/rectanglesquare/rectangle• Rotate the paper for each segmentRotate the paper for each segment

Bounding Box and Construction LinesBounding Box and Construction Lines

PlanPlan• choose proper scale and choose proper scale and

orientationorientation• don’t crowd sketches don’t crowd sketches • Start with a bounding boxStart with a bounding box• Use light straight construction Use light straight construction

lineslines

Draw boundary lines of Draw boundary lines of internal features starting with internal features starting with the largest featuresthe largest features

Sketch dark object lines using Sketch dark object lines using light boundary lines as a guidelight boundary lines as a guide

Multiview SketchingMultiview Sketching Represents a 3-D object Represents a 3-D object

with a series of 2-D with a series of 2-D views in contrast to views in contrast to “pictorials” which show “pictorials” which show all three dimensions in a all three dimensions in a single viewsingle view

Also called orthographic Also called orthographic projectionprojection

Best understood by Best understood by engineers or technically engineers or technically trained peopletrained people

Multiview DrawingMultiview Drawing

PictorialPictorial

Parallel projectionParallel projection

Preserves true relationship between Preserves true relationship between featuresfeatures• The geometry is generally not distortedThe geometry is generally not distorted• Lines that are parallel on the object are Lines that are parallel on the object are

parallel on the drawingparallel on the drawing

Parallel projectorsParallel projectors• The object is projected onto a projection The object is projected onto a projection

plane as a shadow is projected where the plane as a shadow is projected where the rays form the light source are parallel.rays form the light source are parallel.

• Projection from one view to another is Projection from one view to another is accomplished with parallel projection accomplished with parallel projection lineslines

Parallel versus Perspective ProjectionParallel versus Perspective Projection

ParallelParallel

PerspectivePerspective

ParallelParallel

PerspectivePerspective

Projection Planes versus ViewsProjection Planes versus Views Projection planes: Projection planes: • Object formed from projection lines projected Object formed from projection lines projected

perpendicularly onto a projection plane perpendicularly onto a projection plane • Planes: Horizontal, frontal, and profilePlanes: Horizontal, frontal, and profile• Each projection plane is perpendicular to adjacent Each projection plane is perpendicular to adjacent

projection planesprojection planes Principle viewsPrinciple views• The object is rotated 90 degrees about the horizontal or The object is rotated 90 degrees about the horizontal or

vertical axis to give six principle views (top, bottom, vertical axis to give six principle views (top, bottom, front, rear, left, and right side)front, rear, left, and right side)

• Common views: top, front, and right sideCommon views: top, front, and right side

Only use Necessary Views Only use Necessary Views

One view drawings One view drawings • Stamped, thin or extruded parts Stamped, thin or extruded parts • Specify thickness with a noteSpecify thickness with a note

Two view drawingsTwo view drawings• Cylindrical partsCylindrical parts• Show the circular and Show the circular and

rectangular viewrectangular view Three view drawingsThree view drawings

• Usually sufficient for all other drawingsUsually sufficient for all other drawings• Top, front, and right side viewTop, front, and right side view

Orientation and Placement of ViewsOrientation and Placement of Views

The most descriptive view The most descriptive view should be selected as the should be selected as the front viewfront view

The natural orientation of the The natural orientation of the part should be preserved if part should be preserved if possiblepossible

Views must be alignedViews must be aligned• Top view above front viewTop view above front view• Right view to the right of front Right view to the right of front

viewview

Hidden linesHidden linesHidden linesHidden lines

Represented with dashed Represented with dashed lineslines

Precedence of lines Precedence of lines (visible, hidden, center)(visible, hidden, center)

Views should be selected Views should be selected to minimize the use of to minimize the use of hidden lines most hidden lines most descriptive view should descriptive view should be selected as the front be selected as the front viewview

Third Angle Projection Associated with English Third Angle Projection Associated with English unitsunits

First Angle Projection Associated with SI units First Angle Projection Associated with SI units

First Versus Third Angle ProjectionFirst Versus Third Angle ProjectionFirst Versus Third Angle ProjectionFirst Versus Third Angle Projection

ANSI SymbolANSI Symbol

Fold LinesFold Lines

Represents a 90 degree fold between views Represents a 90 degree fold between views Generally not shown on engineering Generally not shown on engineering

drawings except when views other than the drawings except when views other than the principle views (auxiliary views) are used.principle views (auxiliary views) are used.

Labeled as: H/F, F/P, F/1, 1/2Labeled as: H/F, F/P, F/1, 1/2

Terminology to Relate ViewsTerminology to Relate Views

Adjacent viewAdjacent view• A view that is separated by a fold lineA view that is separated by a fold line• The top view is an adjacent view to the front viewThe top view is an adjacent view to the front view

Central ViewCentral View• A view that is between two adjacent viewsA view that is between two adjacent views• The front view is the central view of the top, front, The front view is the central view of the top, front,

and right side viewand right side view

Related viewsRelated views• Two views that are adjacent to a central viewTwo views that are adjacent to a central view• The top and right side view are related views since The top and right side view are related views since

they are both adjacent to the front viewthey are both adjacent to the front view

Constructing a New ViewConstructing a New View

The top and front views The top and front views of a surface are shownof a surface are shown

The The fold linefold line represents represents a 90 degree fold a 90 degree fold between the viewsbetween the views

Parallel Parallel projection linesprojection lines are perpendicular to the are perpendicular to the fold linefold line

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Constructing a New ViewConstructing a New View

A vertical A vertical fold linefold line is drawn at an is drawn at an arbitrary distance from the front viewarbitrary distance from the front view

Parallel Parallel projection linesprojection lines are drawn are drawn from each vertexfrom each vertex

The The common depthcommon depth between the top between the top and side view is used to locate each and side view is used to locate each vertex on the projection linesvertex on the projection lines

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Sketching as Part of the Creative Sketching as Part of the Creative Design ProcessDesign Process

Quickly translate Quickly translate thoughts to paperthoughts to paper

An effective means An effective means of communication of communication

Stimulates creativity Stimulates creativity and visualizationand visualization

Sketching Allows for the Quick Sketching Allows for the Quick Translation of Thoughts to PaperTranslation of Thoughts to Paper

Commit thoughts to paper before you Commit thoughts to paper before you lose an idealose an idea

Avoid the of use mechanical tools (drawing tools are Avoid the of use mechanical tools (drawing tools are helpful for beginners)helpful for beginners)

Does not need to be an exact representationDoes not need to be an exact representation• objects may be simplifiedobjects may be simplified• parts may be missingparts may be missing

Avoid erasingAvoid erasing• as new ideas are developed make new sketchesas new ideas are developed make new sketches• start with light lines and then darken with darker lead or start with light lines and then darken with darker lead or

heavier strokesheavier strokes

Sketching is An Effective Means Sketching is An Effective Means of Communicationof Communication

Understand your audience Understand your audience • Who is looking at the sketches?Who is looking at the sketches?• What details are they interested in?What details are they interested in?• What type of sketch will they best understand?What type of sketch will they best understand?

Follow standard practicesFollow standard practices• You may not always accompany your sketchesYou may not always accompany your sketches• Others may misinterpret your drawingOthers may misinterpret your drawing

Sketches provide a log of ideas that were Sketches provide a log of ideas that were considered in a brainstorming sessionconsidered in a brainstorming session

Sketching Stimulates Creativity Sketching Stimulates Creativity and Helps Visualization and Helps Visualization

The process of sketching ideas that are partially The process of sketching ideas that are partially developed often aids the design processdeveloped often aids the design process• do not wait until you have a clear picture before you do not wait until you have a clear picture before you

start sketchingstart sketching• allow yourself the freedom to make mistakesallow yourself the freedom to make mistakes

Visualization of the entire design is essential but Visualization of the entire design is essential but often impossible without aid of sketches often impossible without aid of sketches

AppendixAppendix

Engineering GraphicsEngineering Graphics

Make a Quick SketchMake a Quick Sketch

How many of the nine views consisted of a How many of the nine views consisted of a square bounding box?square bounding box?

How many of the nine views are the same?How many of the nine views are the same? How many of the nine views consisted of only How many of the nine views consisted of only

vertical or horizontal lines?vertical or horizontal lines? What is the volume of each object (Cube=8 inWhat is the volume of each object (Cube=8 in33)?)?

You will have ten seconds to make a You will have ten seconds to make a sketch of each object shown below sketch of each object shown below before being asked a few questions before being asked a few questions about the objects.about the objects.