Chapter 5Sketching Applications

IntroductionSketching (i.e., freehand drawing) Drawing without drafting equipmentOnly paper, pencil, and an eraser neededFast, visual communicationAsset for communicating technical concepts

IntroductionSketching may be used by:DraftersComputer-aided draftersArchitectsDesigners

Sketching Tools and MaterialsPencils Should have soft leadCommon No. 2Mechanical pencil with H, F, or HB leadAutomatic 0.7-mm or 0.9-mm pencil with F or HB leadPoint should be slightly roundedPaperAlmost any type works

Sketching Straight Lines

Sketching Circular LinesTechniques:Trammel methodHand-compass methodNail-and-string method

Measurement Lines and ProportionsAll lines are related in sketchesSize and directionSketches should be proportionalActual size depends on paper and sketch sizePencils May used as a ruler for measurement

Measurement Lines and Proportions (contd.) Blocking Helps determine shapes and proportions

Introduction to Multiview SketchesMultiview projectionViews of an object as projected upon two or more picture planes in orthographic projectionElevation viewsTwo-dimensional views established by a line of sight perpendicular to the object surface

Isometric SketchesProvide a three-dimensional (3D) pictorial representation of an objectIsometric lines are on or parallel to one of the three original isometric axesCircles and arcs appear as ellipses

Orthographic ProjectionProjection of features of an object onto an imaginary plane (i.e., plane of projection)Projection of features is made by lines of sight perpendicular to the plane of projection

Multiview ProjectionEstablishes two or more views of an object as projected on two or more planes Uses orthographic projection techniquesElevationsTwo-dimensional exterior views of a structureProper view selectionSix primary views

Projection of Features from an Inclined PlaneIn multiview projection, features of objects that are: Parallel to projection planes appear true size and shapeNot parallel to projection planes are foreshortened, and not in true size and shape