Lecture#4

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MULTIVIEWPROJECTION

ThisweekYou will learn multi-view projection.The steps to follow are:◦Projections (ISO-E & ISO-A)◦Multi-view drawings◦Views (Basic, Auxiliary, Detailed etc.)◦Sketching 2-D Geometry◦Assignment # 3

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PrinciplesORTHOGRAPHICPROJECTION

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Projections

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Multi-viewprojection (Orthographicprojections):aredrawnasmultiviewdrawings,whichshowflatrepresentationsofprincipalviewsoftheobject.

Perspectiveprojections aredrawingswhichattempttoreplicatewhatthehumaneyeactuallyseeswhenitviewsanobject.

AxonometricProjections: arethree-dimensionaldrawings,andareofthreedifferentvarieties:Isometric,DimetricandTrimetric.

ObliqueProjections: actuallyshowthefullsizeofoneview.

ParallelProjection isatypeofprojectionwherethelineofsightorprojectorsareparallelandareperpendiculartothepictureplanes.

Theattributesofprojectionmethods

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Whatisorthographic?

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– theplaneuponwhichthefrontalviewisprojected

– theplaneuponwhichthetopviewisprojected

– theplaneuponwhichthesideviewisprojected

Orthographic projection is a method of producing a numberof separate two-dimensional inter-related views, which aremutually at right angles to each other. Using this projection,even the most complex shape can be fully described.

ThewayofcommunicatingideasthateverybodyunderstoodwasaproblemthatfacedGaspardMonge(asanEngineerintheFrenchMilitary).

Hedevisedasystemthatcouldbeusedtocommunicateanobjecttoanyoneacrosstheworld.

Historyoforthographic

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ThissystemiscalledOrthographicProjectionandwasquicklyadoptedbyarmyengineers.

OrthographicProjections

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Orthographic projections aredrawings where the projectors,theobserverorstationpointremainparalleltoeachotherandperpendiculartotheplaneofprojection.

Orthographic projections arefurther subdivided into axonometricprojectionsandmulti-viewprojections.

Effectiveintechnicalrepresentationofobjects.

Projectionsystems

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Orthographicprojection

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Orthographicprojection

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ProjectionSymbols

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MiterlineOrthographicProjectionutilizesaMiterLinedrawnat45degreeswhichenablesinformationtobeprojectedfromthetopviewtothesideview,andfromthesideviewtothetopview.

RES112E– COMPUTERAIDEDTECHNICALDRAWING2015@ITU

PrinciplesMUTLIVIEWDRAWING

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Whatismultiview?

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InvolvesvisualizationandimplementationoAbilitytoseeanobjectclearlyinthemind’seye.oProcess(steps)ofdrawingtheobject

Anothernamefororthographicprojectionismulti-viewdrawing.Multi-view (multiplanar) projection is a method bywhich the exact shape of an object can berepresented by two or more separate viewsproduced on projection planes that are at rightangles to each other.

oMultiview drawing is classified as a parallel projectiontechnique, because the lines of sight used to view theobject are parallel

oA system that allows you to make a two-dimensionaldrawing of a three-dimensional object.

oThe images are called “views“.

Multiviewdrawing

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FRONTL.SIDE R.SIDE

TOP

BOTTOM

BACK

Thereare9differenttypesofviewsusedforengineeringdrawings,namely

Basicviews

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Auxiliaryview

DetailedviewBottomview

Rearview

Frontview

Topview Sectionview

Left-sideview

Right-sideview

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AlphabetofLines

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Linetypes

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You will draw the centerlines for the circle. Center linesfor holes must be included in all views. A centermark andfour lines extending beyond the four quadrant points areused.

Center Lines

Thecenterlineisusedto:o Showtheaxisofsymmetryofafeatureorparto Indicateapathofmotiono Showthelocationforboltcirclesorother

circularpatterns

Linetypes

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You should follow at least three general practices whendrawing hidden lines to help prevent confusion and tomake the drawing easier to read.

Hidden Lines

o clearly show intersections using intersecting linesegments

o clearly show corners, using intersecting linesegments

o leave a noticeable gap between aligned continuouslines and hidden lines

Adjustinglinteypescale

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LTSCALE determines the relative length of dashesin linetypes such as hidden and center lines.Setting a linetype scale ensures that the lines youdraw are represented properly on the screen andwhen the drawing is plotted.

Command : LTSCALEEnter new linetype scale factor <1.000> : 0.5Regenerating model.Command :

Linetypes

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Widthofslotprojectedintotopview

LinePrecedence

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Different types of lines often align with each other withinthe same view.

Theruleisthatcontinuouslinestakeprecedenceoverhiddenlines,andhiddenlinestakeprecedenceovercenterlines.

Ifyoushowtheshortendsegmentswereacenterlinewouldextend,besuretoleaveagap.

Theorderofprecedenceoflines

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Visible object lines

Hiddenlines

Centerlineorcuttingplaneline

Crosshatch/sectionlines

Dimensionandextensionlines

Breaklines

LinePrecedence

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Continuouslineoverahiddenline

Hiddenlineoveracenterline

Continuouslineoverahiddenline

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You will learn creating section view. The stepsto follow are:◦Cutting plane◦Kind of sectional views (full, half, etc.)◦Section line symbols◦Conventional practice◦Assembly sections◦Creating section views in AutoCAD◦Assignment # 4

Thefollowingweek

TeamMeetingDURATION1HOUR

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http://library.itu.edu.trLibrarywebsite:

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https://intweb.tse.org.tr/Standard/Standard/StandardAra.aspxTSEwebsite:

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http://online.tpe.gov.tr/EPATENT/servlet/EPreSearchRequestManagerTPEwebsite:

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http://www.epo.org/index.htmlEuropeanPatentOfficewebsite:

Meetingminute

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Assignment#3

Page

Figure

You will sketch and complete viewsSubmit the assignment on timeUpload file into NINOVA