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Auxiliary Views Auxiliary Views

Engineering GraphicsStephen W. Crown Ph.D.


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Obj ectiveObj ectiveT o understand how to generate views thatshow inclined and oblique surfaces in trueshape in multiview drawingsT o better understand the manipulation of 3-D objects using successive 90 degreerotations in preparation for solid modeling


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OutlineOutlineDefinition and UseFold Line MethodPrimary Auxiliary Views

Review of descriptive geometryExample: Inclined surface

Secondary Auxiliary ViewsExample: Oblique surfaceExample: A surface with no true length lines


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Auxiliary Vs. Principle Views Auxiliary Vs. Principle ViewsPrinciple planes

Horizontal ( T op and bottom view)

Frontal (Front and back view)Profile (Left and right side view)

Auxiliary views

Definition: An orthographic view that is projected into a plane that is not parallel to anyof the principle planesPurpose: T o show the true shape of a detail thatdoes not lie in on of the principle planes


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R eview: Fold Line Method R eview: Fold Line Method A fold line (hinge) may be placed betweenadjacent views to aid in the construction andinterpretation of multiview drawingsProjection lines are always perpendicular tofold linesT he distance from a fold line to any specific

point on an object is the same for anyrelated views (ex. top and side view)Fold lines represent a 90 degree rotation inviewpoint


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E xample: Fold Line Method

E xample: Fold Line Method

Distances from the fold linein View A are equal to thedistance from the fold line inView CFollow projection lines tokeep track of vertices

Use offset when creatingView C from View A & B

Note that the projection linesare always perpendicular tofold lines.


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Primary Auxiliary View Primary Auxiliary ViewDefinition: Any view that is projected from(adjacent to) one of the principle views and whichis not parallel to any of the principle planesA primary auxiliary view is perpendicular to onlyone of the principle planesAny inclined surface may be shown in true shape

in the appropriate primary auxiliary viewIf the fold line for an auxiliary view is parallel tothe edge view of an inclined surface the inclinedsurface will appear in true shape in the auxiliaryview


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E xample: Primary Auxiliary E xample: Primary Auxiliary

ViewsViews Use the UCS commandto rotate about the Z axisand align the x axis upwith the inclined surface

Project perpendicular projection lines from theinclined surface(OR T HO)

Determine the depth of each point from relatedviews (OFFSE T )Use DDOSNAP to

quickly select features


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Pro jection Planes Pro jection Planes

A fold line represents the projection plane for the adjacent view

A line appears true length if it liesin a plane parallel to the projection

planeA line which is not parallel to the

projection plane appearsforeshortenedA line which is perpendicular to the

projection plane appears as a point


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Lines Lines

A line which is parallel to a fold linewill appear true length in the adjacentviewA true length line which is

perpendicular to a fold line willappear as a point in the adjacent view

Line 1-3 is parallel to the fold line inthe right side view and true lengthline in the front viewLine 1-2 is true length in the rightside view and is a point in the frontview


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Lines Lines

All views adjacent to a point view of a line willshow the line in true length

A line which does notappear true length in any of

the principle views iscalled an oblique line


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S urfacesS urfaces

A Surface appears in true shape(undistorted) if it is parallel to the

projection planeA surface appears as an edge parallel tothe fold line in all views adjacent to thetrue shape view of the surfaceIf any line on a surface appears as a

point then the surface will appear as anedgeA surface which does not appear as anedge in any of the principle views is

called an oblique surface


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S econdary Auxiliary Views

S econdary Auxiliary ViewsAn oblique surface

requires a secondaryauxiliary view to show

the surface in true shape


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Definition: A secondary auxiliary view isany view which is not perpendicular to any

of the principle viewsPurpose: A secondary auxiliary view is usedto show the true shape of an oblique surface

A secondary auxiliary view is constructedas an auxiliary view to a primary auxiliaryview using fold lines and perpendicular

projectors


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E xample: S econdary Auxiliary E xample: S econdary Auxiliary

ViewViewT he top view shows the obliquesurface

A secondary auxiliary view isneeded to show the surface in trueshapeT he lengths of sides and angles

are distorted in all other viewsPerpendicular projection lines andreference planes are used toconstruct the right side view fromthe front and top view


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ViewView A true length line on theoblique surface is identifiedin the right side viewPlacing a fold line which is

perpendicular to the truelength line gives the edgeview of the surfaceT his auxiliary view is a

primary auxiliary viewT he edge view of the surfaceis needed to obtain the trueshape view


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ViewView A fold line which is draw parallel to the edge viewof the oblique surface

gives the secondaryauxiliary view showingthe surface in true shapePerpendicular projectors

are used to determine thelocation of verticesOften only the inclined or oblique surface is shown

in auxiliary views


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ViewViewSimplify the constructionof drawings by startingwith only a portion of thedrawingT he right side view isconstructed by measuringalong projection lines in

the top viewVertices are numbered tohelp keep track of correctdistances from reference

planes


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E xample: S econdary Auxiliary View E xample: S econdary Auxiliary View

A true length line is identified in the right side viewline 2-4 is parallel to the fold line in the front view, thereforeline 2-4 is a true length line in the right side view

A fold line perpendicular to the true length line gives theedge view of the oblique surface


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E xample: S econdary Auxiliary View E xample: S econdary Auxiliary View

Use UCS to rotate about the Z axis and align the X axis with the edge

view of the oblique surfacePerpendicular projection lines are constructed (OR T HO)T he distance along projection lines are measured in relative views(OFFSE T and DDOSNAP)

T he secondary auxiliary view shows the oblique surface in true shape


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Memorize These S tatements Memorize These S tatements

Before The Quiz Before The QuizA fold line that is parallel to a linegives a view that shows the true

length of the lineA fold line that is perpendicular toa true length line on a surfacegives a view that shows the surfaceas an edge.A fold line that is parallel to theedge view of a surface gives a viewthat shows the true shape


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Another E xample Another E xample

T he top view and frontview of a surface is

shownIs an auxiliary viewneeded to show thesurface in true shape?Yes: T he surface doesnot appear as an edge ineither view


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E xample E xample

Construct the rightside view using

projection lines andreference planes

Note that there are no

true length lines inany of the principleviews


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ViewView Since the surface doesnot appear as an edge inany of the principleviews the surface isoblique and requires asecondary auxiliary viewA line is drawn on thesurface which is parallelto the fold line betweenthe front and right sideviewT his line appears as atrue length line in theright side view


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ViewViewT he true length line is used to get an edge view of the surface

A fold line perpendicular to the true length line gives a point viewof the line in the adjacent view

Since the line is on the surface the surface will appear as an edge


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ViewViewT he secondary auxiliaryview gives the true

shape of the surfaceT he secondary auxiliaryview is constructed by

placing a fold line

parallel to the edge viewof the surface


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ViewView Fold lines are labeled by the name of the principle plane or the level of auxiliaryview

Primary auxiliary view (1)

Secondary auxiliary view (2)


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H elpful Visualization Tools H elpful Visualization ToolsLabel surfacesLabel vertices - List nearest vertexfirst at each location (1,2)

Follow construction lines todetermine locationEqual number of sides - A surfacewith 3 sides will have three sides in

every viewParallel edges - If lines are parallelin one view they will be parallel inevery view

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