Multi-view Drawing. Gamal Prather. Multi-view Drawings. Pictorial sketches are great for engineers to explain ideas and communicate what the final part will look like to the customer. Unfortunately, pictorial drawings have some disadvantages.
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Multi-view Drawing Gamal Prather
Multi-view Drawings • Pictorial sketches are great for engineers to explain ideas and communicate what the final part will look like to the customer. • Unfortunately, pictorial drawings have some disadvantages. • Foreshortened views and distorted features do not allow for accurate prototyping. • Many times, for parts to be accurately depicted, you need straight on views of each surface.
Orthographic Drawings • These straight-on views are called ORTHOGRAPHIC PROJECTIONS • aka MULTIVIEW DRAWINGS • These views are perpendicular to a line of sight • There are 6 of these views to any object
Orthographic Drawing The arrows represent the line of sight associated with each view. View the Orthographic Drawings for this object
Orthographic Principal Views Front, Top and Right views are used most often. You can see how other views resemble these three except they are not as clear due to hidden lines. Note how the views are oriented. Each view is adjacent to the other as if they were unfolded from a 3D shape. ISO
Orthographic Angle of Projection • The example you have just seen is shown in THIRD ANGLE projection • This is the standard in the United States and Canada • The rest of the world draws in FIRST ANGLE projection
In 3rd angle projection, the projection planes used to create views are as shown in red. Top Front Right Side Orthographic Spatial Quadrants and Planes This sketch shows the quadrants where the angles of projection are made from
Orthographic 3rd Angle Projection Views are projected onto planes that exist on the face of that view. Arrows show the direction of the projection ISO Symbol
Side Top In 1st angle projection the projection planes used to create the views are as shown in red. Front Orthographic Spatial Quadrants and Planes
Orthographic 1st Angle Projection Views are projected onto planes that exist on the opposite face of the view you want to display. The arrows show the direction of the projection. ISO Symbol
View Selection • Finding the best view of a part can be tricky • Two or more sides may look like the best solution for a front view. • On the next slide is a list of characteristics that you should use in choosing your views.
View Selection Criteria • The front view should show the ... • Shows best shape and characteristic contours • Longest dimensions • Fewest hidden lines • Most stable and natural position
View Selection No hidden lines in any views Most natural position for isometric view Best shape description Longest Dimension
Selecting Number of Views • How many views do you need? • Usually not more than 3, but you may only need one or two.
One View Selection Uniform shape. Two views will be identical All dimensions easily shown on one view
One View Selection It is also possible to have one view drawings of objects that are flat and have even thickness. Gauges and gaskets are two such objects. We have a gauge here on the left.
Two View Selection Symmetrical parts. A third view would be identical to the other views Second view is necessary for depth.
Line Precedence • Different line types frequently must be drawn in the same space • LINE PRECEDENCE helps us decide which lines to draw • Generally you should draw … • Object lines over hidden lines and centerlines • Hidden lines over centerlines • Cutting plane lines over centerlines
Precedence of Lines An object line here takes precedence over the center line. However we draw short thin lines beyond the object to show there is a center line underneath the object line.
Precedence of Lines Object lines took precedence over the hidden lines you would see from the hole. The center line in the top view would show the depth of the hole as well as the right side view.
References • Madsen, David A., Shumaker, Terence M., Stark, Catherine, Turpin, J. Lee, Engineering Drawing and Design Second Edition,Delmar Publishers, 1996, ISBN 0-8273-6720-1. • Brown, David, You Can Draw, North Light Books, Cincinnati, Ohio, 1986, ISBN 0-89134-216-8. • Olivo, Dr. C. Thomas, Olivo, Thomas P., Basic Blueprint Reading and Sketching Sixth Edition, Delmar Publishers Inc., 1993, ISBN 0-8273-5740-0. • Johnson, Cindy M., Lockhart, Shawna D., Engineering Design Communication, Prentice Hall, 2000, ISBN 0-201-33151-9. • Spencer, Henry Cecil, Dygdon, John Thomas, Novak, James E; Basic Technical Drawing 6th Edition; Glencoe McGraw Hill; New York, New York,1995, ISBN 0-02-685660-3.
Practice Practice Practice Practice Practice Practice Practice Practice Do you want to be a good sketcher? First Slide