2 Learning GoalsHow to Unfold the “Glass” Box to draw Perpendicular Projection (OrthoGraphic) ViewsDetermine the Minimum No. of Views Needed to Fully Describe an ObjectProperly Place Views Relative to Each OtherWhich Views show Which Combination of the Object’s H, W, & D
3 Learning Goals contUnderstand the Criteria for Selecting the CENTRAL ViewApply the Guidelines for the Proper Use of Hidden LinesDetermine When Lines/Shapes are in TRUE Length/Shape as opposed to FOREshortenedConstruct MultiView Orthographic Projection Drawings
4 OrthoGraphic View Drawing All Objects Are Three Dimensional (3-D)Height, Width, and DepthDrawings are done on a 2-D surfaceMultiview Sketching (Orthographic Projection) Represents A 3-D Object With A Series Of 2-D ViewsBest Understood By Technical PeopleIn Contrast To “Pictorials” Which Show Three Dimensions In A Single View
5 Projection Planes Versus Views Objects are Formed From Parallel “Sight Lines” Projected Perpendicularly Onto A Projection PlaneHorizontal, Frontal, ProfileEach Projection Plane Is Perpendicular To the Adjacent Projection PlanesLines/Features Parallel to Proj Plane are TRUE Length/Size
6 Principle ViewsThe Object Is Rotated 90° About The Horizontal Or Vertical Axis To Yield the Six Principle ViewsTop, Bottom, Front, Rear, Left & Right SideCommon views:TopFrontRight Side
7 View SelectionOnly Use The Views That Are Needed To Represent The ObjectOne view drawingsStamped part: Specify uniform thickness with a noteTwo view drawingsA Cylindrical PartThree view drawingsUsually Sufficient For All Other ObjectsTop, Front, And Right-Side Views
8 General GuidelinesThe Most DESCRIPTIVE View Should Be The FRONT, or CENTRAL, ViewViews MUST Be ALIGNEDTop View ABOVE Front ViewRight-Side View To The RIGHT Of Front ViewHidden linesRepresented With Dashed LinesPrecedence of lines (Visible, Hidden, Center)Views Should Be Selected To MINIMIZE The Use Of HIDDEN LINES
9 Parallel Projection Preserves true relationship between features Parallel lines are drawn parallelThe geometry is generally not distortedParallel projectorsLight from a point-source at an -distance
10 The Glass BoxProjection Planes Placed Parallel to the Principle Faces of an Object Form a Glass BoxWhat An Observer Would See From the OUTSIDE Looking IN
11 Unfolding The Glass Box Hinge the Four Intersections on The Frontal Plane And “Flatten Out” the BoxMaintains the TRUE-Length Of Lines Parallel to the Viewing PlanesThe 5 Hinge Lines are Known as FOLDING Lines
13 Common DimensionsEvery 3-D Object Can Be Described By its Height, Width, and DepthThe Views from the Glass Box Share These Dimensions in This Form
14 Central View = Front View Criteria for Selecting Central ViewFront View Shows The Shape Of The Object MOST ClearlyChose Front View So That It Has A Large Number Of Normal () SurfacesMinimize Hidden LinesShow The Object In A Usual Or Operating Positioni.e., Do NOT show the Object “UpSide Down”
16 Producing a Multiview Drawing Select Front View As BeforeAlign View Bounding Boxesi.e., Block-In ViewsApprox. Center on Drawing BorderDraw Features Using Instruments/CADTrue Shapes RemainProject Between ViewsUse 45° “Mitre” Lines to Xfer Depth DimsLabel Vertices if Needed
17 Align Bounding Boxes TOP FRONT RIGHT WIDTH DEPTH WIDTH DEPTH Miter line at 45°HEIGHTHEIGHTFRONTRIGHT
18 Construction Lines to Xfer Dims TOPUse 45° Miter Line to Transfer Dims Between Top & Side ViewFRONTRIGHT
19 Label Vertices A B C A B C A B C ,A B C An Intermediate Step to Aid ConstructionOnly If needed to Clarify Positions For the DesignerABC,ABC
21 True Length Vs. Foreshortened Only Lines/Planes that Are PARALLEL to the Projection Plane are (LoS Plane) show in TRUE LENGTH/SHAPEOthers are ForeShortened in the View
22 Hidden Line UsageHidden Lines can Greatly-CLARIFY or Greatly-CONFUSE a Drawing ViewVisible Lines are Usually EasyExceptions = Fillets & Rounded EdgesCreating Useful Hidden Lines RequiresJudgmentAdherence to Convention
23 Draw Hidden Lines Dashes are 2X to 3X Longer Than Spaces .e.g.; Dashes 1/8” (3mm) Long, Spaces 1/16” (1.5mm) Long.Should Intersect Neatly Except Where A Line Of A Different Linetype Would Appear To Be Extended“Jump” Visible Lines That They CrossClosely Spaced Parallel Hidden Lines Are Drawn With The Dashes STAGGERED if Possible
24 Conventions for Hidden Lines Hidden lines should join neatly with visible lines except when it causes a visible line to be extended. When two different lines join to form a single line, leave a gap on the less important line.Hidden lines should join neatly to form “T” or “L” shaped inter- sections.Hidden lines should jump visible lines that they do not intersect.It is permissible for a hidden line to cross a visible line.
25 More Hidden Line Conventions Stagger the dashes on closely spaced parallel hidden lines.Hidden line dashes should intersect neatly to from clear corners, as in the bottom of this drilled hole.Intersecting hidden lines should form neat corners, as in this countersunk hole.
26 Curved Hidden LinesCurved hidden lines should not extend a visible curve in the same direction. Leave a gap on the hidden line so that you can easily see where the visible line ends.Curved hidden lines dashes should extend to the point of tangency. Don’t end with a gap at the point of tangency. It makes it hard to see the location.
27 Hidden Lines Hidden Lines Can be Made A number of ways in AutoCAD Draw Line in a LAYER with Hidden FormDraw a SOLID Line, then CHANGE to a Hidden LAYER (Described Last Lecture)Draw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES ToolBarDraw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES Side-Menu
28 Chg Hidden-Line by ToolBar WantSelect HIDDENSelect Line to Light-Up HandlesClick on “Layer Control” Box to PullDown LineTypes MenuDeactivate Grips by Hitting Esc
29 Chg Hid-Ln by Properties Menu WantRt-Click Line or Grips to Activate the Context PullDown MenuSelect propertiesDouble-Click an END GripSelect Line to Light-Up HandlesActivate the Properties Side Menus by one of
30 Chg Hid-Ln by Properties Menu On Properties Side Menu Activate the LineType PullDownSelect Hidden and Deactivate Grip by Hitting EscNOTEThe Prop-ToolBar or Prop-Menu Can also Change Line Color, and Thickness
31 Visualization: Ortho → 3D For a Practicing Engineer with Detail-Design Assistance, READING Projection Drawings Is as Important as MAKING themThe Practicing Engineer Must be Able to Think in 3-D Using 2-D Projectionsi.e., To Visualize a 3-D Object Given Front, Top and Side ViewsThis is Inverse of Creating Views from the 3-D Object
32 Visualization Aids Using Labels on Multiview Drawings 1S1S33Using Labels on Multiview DrawingsLabel surfaces; e.g.,Label surfaces; e.g.,SLabel vertices; e.g., 1,3
33 Visualization Continued Recognize Similar Shapes in Different ViewsEqual number of sidesParallel edgesBest Way to “Read” Engineering Drawings is the “Writing” of Great Numbers of them
34 Eliminate Unnecessary Views Show Only The Views Needed Drawing To Fully Define The Shape Of The ObjectChoose The Views Which Show The Shapes Of The Features Most ClearlyThe Right Side View Is Preferred To The Left Side View If They Show The Object Equally WellThe Top View Is Preferred To The Bottom View If They Show The Object Equally WellShowing Only The Necessary Views Saves Time, Makes The Drawing Less Cluttered, And Makes It Easier To Interpret
35 Try 0.7mm MechPencil w/ HB or B Lead All Done for TodayTry 0.7mm MechPencil w/ HB or B Lead".. indeed, far and away the most prolific writer in the history of the subject" writes Howard Eves in An Introduction to the History of Mathematics. Euler's contribution to mathematics is represented here by a few of the notations conventionalized by him or in his honor. Around the world, these are read, written, and spoken thousands of times every day:e for the base of the natural logarithm (a.k.a. "the calculus number") a, b, c for the sidelengths of a triangle ABC f(x) for functional value R and r for the circumradius and inradius of a triangle sin x and cos x for values of the sine and cosine functions i for the imaginary unit, the "square root of -1" capital sigma for summation. capital delta for finite difference.Euler grew up near Basel, Switzerland, and studied at an early age under Johann Bernoulli. He finished studies at the University of Basel when only 15 years old. From 1727 to 1741, Euler worked in St. Perersburg, Russia, and then moved to the Akademie in Berlin. In 1766 he returned to St. Petersburg, where he remained.
37 Recall Std LinesVisible lineHidden lineHatchingCenterlineDimensionExtensionLeaderCutting PlaneViewing PlaneShort breakLong breakPhantomStitchChainLine Patterns Communicate What The Line Represents In The DrawingLine Patterns Tell You Information Such As Whether The Line Is Hidden, Visible, Or A CenterlineLine Precedence:Visible → Hidden → Center
38 Hidden Line Example Block-In sizes 2 6 FView → 15W x 7H TView → 15W x 6DRView → 7H x 6D6112Ø2334433483111Hx2D Groove, Ctr’d
39 OrthoGraphic View Sketching Block-In Views Using Approximately True-Length DimensionsEngr-Comp-Pad Grid is Useful for ScalingBlock-In all Details Such as Corners, Notches, Circles, etc.Dim All Construction Lines with EraserDarken All Final Lines to Emphasize Object in All Views
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