# OrthroGraphic View Dwgs-1

## Presentation on theme: "OrthroGraphic View Dwgs-1"— Presentation transcript:

OrthroGraphic View Dwgs-1
Engineering 22 OrthroGraphic View Dwgs-1 Bruce Mayer, PE Licensed Electrical & Mechanical Engineer

Learning Goals How to Unfold the “Glass” Box to draw Perpendicular Projection (OrthoGraphic) Views Determine the Minimum No. of Views Needed to Fully Describe an Object Properly Place Views Relative to Each Other Which Views show Which Combination of the Object’s H, W, & D

Learning Goals cont Understand the Criteria for Selecting the CENTRAL View Apply the Guidelines for the Proper Use of Hidden Lines Determine When Lines/Shapes are in TRUE Length/Shape as opposed to FOREshortened Construct MultiView Orthographic Projection Drawings

OrthoGraphic View Drawing
All Objects Are Three Dimensional (3-D) Height, Width, and Depth Drawings are done on a 2-D surface Multiview Sketching (Orthographic Projection) Represents A 3-D Object With A Series Of 2-D Views Best Understood By Technical People In Contrast To “Pictorials” Which Show Three Dimensions In A Single View

Projection Planes Versus Views
Objects are Formed From Parallel “Sight Lines” Projected Perpendicularly Onto A Projection Plane Horizontal, Frontal, Profile Each Projection Plane Is Perpendicular To the Adjacent Projection Planes Lines/Features Parallel to Proj Plane are TRUE Length/Size

Principle Views The Object Is Rotated 90° About The Horizontal Or Vertical Axis To Yield the Six Principle Views Top, Bottom, Front, Rear, Left & Right Side Common views: Top Front Right Side

View Selection Only Use The Views That Are Needed To Represent The Object One view drawings Stamped part: Specify uniform thickness with a note Two view drawings A Cylindrical Part Three view drawings Usually Sufficient For All Other Objects Top, Front, And Right-Side Views

General Guidelines The Most DESCRIPTIVE View Should Be The FRONT, or CENTRAL, View Views MUST Be ALIGNED Top View ABOVE Front View Right-Side View To The RIGHT Of Front View Hidden lines Represented With Dashed Lines Precedence of lines (Visible, Hidden, Center) Views Should Be Selected To MINIMIZE The Use Of HIDDEN LINES

Parallel Projection Preserves true relationship between features
Parallel lines are drawn parallel The geometry is generally not distorted Parallel projectors Light from a point-source at an -distance

The Glass Box Projection Planes Placed Parallel to the Principle Faces of an Object Form a Glass Box What An Observer Would See From the OUTSIDE Looking IN

Unfolding The Glass Box
Hinge the Four Intersections on The Frontal Plane And “Flatten Out” the Box Maintains the TRUE-Length Of Lines Parallel to the Viewing Planes The 5 Hinge Lines are Known as FOLDING Lines

The Unfolded Glass Box

Common Dimensions Every 3-D Object Can Be Described By its Height, Width, and Depth The Views from the Glass Box Share These Dimensions in This Form

Central View = Front View
Criteria for Selecting Central View Front View Shows The Shape Of The Object MOST Clearly Chose Front View So That It Has A Large Number Of Normal () Surfaces Minimize Hidden Lines Show The Object In A Usual Or Operating Position i.e., Do NOT show the Object “UpSide Down”

The Primary Views

Producing a Multiview Drawing
Select Front View As Before Align View Bounding Boxes i.e., Block-In Views Approx. Center on Drawing Border Draw Features Using Instruments/CAD True Shapes Remain Project Between Views Use 45° “Mitre” Lines to Xfer Depth Dims Label Vertices if Needed

Align Bounding Boxes TOP FRONT RIGHT WIDTH DEPTH WIDTH DEPTH
Miter line at 45° HEIGHT HEIGHT FRONT RIGHT

Construction Lines to Xfer Dims
TOP Use 45° Miter Line to Transfer Dims Between Top & Side View FRONT RIGHT

Label Vertices A B C A B C A B C ,A B C
An Intermediate Step to Aid Construction Only If needed to Clarify Positions For the Designer A B C ,A B C

Views FULLY Aligned Very FEW Hidden Lines

True Length Vs. Foreshortened
Only Lines/Planes that Are PARALLEL to the Projection Plane are (LoS  Plane) show in TRUE LENGTH/SHAPE Others are ForeShortened in the View

Hidden Line Usage Hidden Lines can Greatly-CLARIFY or Greatly-CONFUSE a Drawing View Visible Lines are Usually Easy Exceptions = Fillets & Rounded Edges Creating Useful Hidden Lines Requires Judgment Adherence to Convention

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 Cross Closely Spaced Parallel Hidden Lines Are Drawn With The Dashes STAGGERED if Possible

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.

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.

Curved Hidden Lines Curved 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.

Hidden Lines Hidden Lines Can be Made A number of ways in AutoCAD
Draw Line in a LAYER with Hidden Form Draw a SOLID Line, then CHANGE to a Hidden LAYER (Described Last Lecture) Draw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES ToolBar Draw a SOLID Line, then CHANGE to a Hidden LINETYPE using PROPERTIES Side-Menu

Chg Hidden-Line by ToolBar
Want Select HIDDEN Select Line to Light-Up Handles Click on “Layer Control” Box to PullDown LineTypes Menu Deactivate Grips by Hitting Esc

Want Rt-Click Line or Grips to Activate the Context PullDown Menu Select properties Double-Click an END Grip Select Line to Light-Up Handles Activate the Properties Side Menus by one of

On Properties Side Menu Activate the LineType PullDown Select Hidden and Deactivate Grip by Hitting Esc NOTE The Prop-ToolBar or Prop-Menu Can also Change Line Color, and Thickness

Visualization: Ortho → 3D
For a Practicing Engineer with Detail-Design Assistance, READING Projection Drawings Is as Important as MAKING them The Practicing Engineer Must be Able to Think in 3-D Using 2-D Projections i.e., To Visualize a 3-D Object Given Front, Top and Side Views This is Inverse of Creating Views from the 3-D Object

Visualization Aids Using Labels on Multiview Drawings
1 S 1 S 3 3 Using Labels on Multiview Drawings Label surfaces; e.g., Label surfaces; e.g., S Label vertices; e.g., 1,3

Visualization Continued
Recognize Similar Shapes in Different Views Equal number of sides Parallel edges Best Way to “Read” Engineering Drawings is the “Writing” of Great Numbers of them

Eliminate Unnecessary Views
Show Only The Views Needed Drawing To Fully Define The Shape Of The Object Choose The Views Which Show The Shapes Of The Features Most Clearly The Right Side View Is Preferred To The Left Side View If They Show The Object Equally Well The Top View Is Preferred To The Bottom View If They Show The Object Equally Well Showing Only The Necessary Views Saves Time, Makes The Drawing Less Cluttered, And Makes It Easier To Interpret

Try 0.7mm MechPencil w/ HB or B Lead
All Done for Today Try 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.

Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege.edu
Engr/Math/Physics 25 Appendix Time For Live Demo Bruce Mayer, PE Licensed Electrical & Mechanical Engineer

Recall Std Lines Visible line Hidden line Hatching Centerline Dimension Extension Leader Cutting Plane Viewing Plane Short break Long break Phantom Stitch Chain Line Patterns Communicate What The Line Represents In The Drawing Line Patterns Tell You Information Such As Whether The Line Is Hidden, Visible, Or A Centerline Line Precedence: Visible → Hidden → Center

Hidden Line Example Block-In sizes 2 6 FView → 15W x 7H
TView → 15W x 6D RView → 7H x 6D 6 11 2 Ø2 3 3 4 4 3 3 4 8 3 11 1Hx2D Groove, Ctr’d

OrthoGraphic View Sketching
Block-In Views Using Approximately True-Length Dimensions Engr-Comp-Pad Grid is Useful for Scaling Block-In all Details Such as Corners, Notches, Circles, etc. Dim All Construction Lines with Eraser Darken All Final Lines to Emphasize Object in All Views