Click here to load reader

CHAPTER 4: ISOMETRIC AND OBLIQUE - UniMAP Notes... · PDF fileOblique Projection In oblique projections the front view is drawn true size, and the receding surfaces are drawn on an

  • View
    226

  • Download
    3

Embed Size (px)

Text of CHAPTER 4: ISOMETRIC AND OBLIQUE - UniMAP Notes... · PDF fileOblique Projection In...

  • CHAPTER4:ISOMETRICANDOBLIQUE

  • Studentsareable: To construct isometric objects from twodimensionalorthographicprojections.

    To draw isometric object and nonisometricobject

    Toconstructisometricellipseondifferentplane

    Todeterminethebestisometricpositions

    Objectives:

  • Introduction:

    Isometric illustration is the method of depiction ideaswhichformedinactual3Dobjects.

    Thismethodcandescribetheobjectshapeeasily.

    This construction could be done based on theobjects shape which viewed from certaindirections.

  • Isometricobjectviewedfromdifferentdirection

  • IsometricSketches

    Isometricprojectionisproducedusing3axes:verticalaxisleftaxisrightaxis

    Theleftandrightaxesareproducedattheangleof30tothehorizontallines

  • Figure below shows the main axis of isometricdevelopedwith30setsquare

    30 30120

  • Figureshowsaboxinisometricdrawing

  • Isometricsketchingfrommultiviewdrawing

  • SelectionofIsometricaxes View (a) is preferred as it reveals moredetailthantheothers.

  • IsometricdrawingSteps:[email protected]uidebox.4.Adddetails i.e.Transfer thedistanceofobjectanddrawtheconstructionlines.5.Darkenvisiblelines.

  • Isometricdrawing:objecthasinclinedsurfaces

  • DrawingofCirclesandArcs

    In isometric drawing, a circle appears as an

    ellipse.

    Sketchingsteps:

    1.Locatethecenterofanellipse

    2.Constructanisometricsquare

    3.Sketcharcsthatconnectthetangentpoints.

  • Fourcentremethodisusuallyusedwhendrawnan

    isometricellipsewithdrawinginstrument.

    SketchingSteps

    1.Locatethecenterofanellipse2.Constructanisometricsquare.3. Construct a perpendicular bisector from eachtangentpoint.4.Locatethefourcenters.5.Drawthearcswiththesecentersandtangenttoisometricsquare.

  • Exampleofisometricellipse

  • DrawingofIrregularcurvesinIsometricdrawing

    Steps:

    1. Construct points along the curve in multiview

    drawing.

    2.Locatethesepointsintheisometricview.

    3.Sketchtheconnectinglines.

  • ObliqueProjection

    Inobliqueprojectionsthefrontviewisdrawntruesize,and the recedingsurfacesaredrawnonanangle togive it a pictorial appearance.This formof projection has the advantage of showing oneface (the front face) of the object withoutdistortion. Generally, the face with the greatestdetailfacesthefront.

    Therearetwotypesofobliqueprojectionused inengineeringdesign.

  • CavalierOblique

    In cavalier oblique drawings, all lines (includingrecedinglines)aremadetotheirtruelength.

  • CabinetOblique

    Incabinetobliquedrawings,therecedinglinesareshortened by onehalf their true length tocompensate for distortion and to approximatemorecloselywhatthehumaneyewouldsee.Itisfor this reason that cabinet oblique drawings arethemostusedformofobliquedrawings.

  • TypicalAnglesofProjection

    In oblique drawings, the three axes of projectionare vertical, horizontal, and receding. The frontview (vertical & horizontal axis) is parallel to thefrontalplaneand theother two facesareoblique(receding).Thedirectionofprojectioncanbetopleft, topright, bottomleft, or bottomright. Thereceding axis is typically drawn at 60, 45, or 30degrees.

  • Typicalanglesofprojection

    TopLeft

    BottomLeft BottomRight

    TopRight

  • CenterlinesinIsometricdrawingCenterlines are drawn only for showingsymmetry or for dimensioning. Normally,centerlines are not shown, because manyisometric drawings are used to communicate tonontechnical people and not for engineeringpurposes.

  • Exercise:1.Drawinfullsizeanisometricviewoftheobject.Thegridsizeis10mmx10mm.

  • 2.Drawinfullsizeanisometricviewoftheobject.Thegridsizeis10mmx10mm.

  • 3.Drawinfullsizeanisometricviewoftheobject.Thegridsizeis10mmx10mm.

  • 4.Draw in full sizeacavalierobliqueviewof theobject. Choose the proper orientation. The gridsizeis10mmx10mm.

    Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28