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Sketching TED 105 Communicating Technical Designs Sketching and Shape Description Straight Lines Circles and Arcs Proportions Generating Technical Designs Sketching Principles of EngineeringTM Unit 2.
TED 105: Communicating Technical Designs • Sketching and Shape Description – Straight Lines – Circles and Arcs – Proportions – Generating Technical Designs Purpose • The main purpose of sketching is to convey ideas Engineers have to use sketches to brainstorm ideas, as well as, to show others what they are working on or what should be designed Sketches are also used to document measurements from the field before they are produced as solid models on the computer Freehand Sketching • Most original designs are first expressed on medium as a freehand sketch • Used for: – Amplifying and clarifying – Recording verbal explanations Technical Sketching • Engineers’ view: ability to render serviceable sketches greater value than skill to create instrument drawings • Freehand sketch should not mean crude and sloppy • Freehand sketch should be made with care and attention to proportion, clarity, and line widths Types of Sketches Scale • Typically not made to any scale • Correct proportions are needed • Size of sketch: – Optional – Determined by: • Complexity of object • Size of paper • Small objects may be enlarged to show details clearly Do you want to be a good sketcher? Purpose • Proper documentation in a notebook is essential When proper documentation is made, ideas are not lost and projects can be duplicated The sketch on the next slide is a sample from a notebook where a sketch was made and notes as well as dimensions have been documented Proposed Notebook Sample Size requirements Shows design details Title Initialed and dated Sketching Techniques • Line Types: Vertical Line Horizontal Line Inclined Line 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 Back Orthographic Spacial Quadrants and Planes Side Top In 1st angle projection the projection planes used to create the views are as shown in red Front 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 Back Orthographic View Selection • Finding the best view of a part can be difficult 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 Orthographic View Selection • Steps in selecting the front – – – – – – Most natural position or use Shows best shape and characteristic contours Longest dimensions Fewest hidden lines Most stable and natural position Relationship of other views • • • • Most contours Longest side Least hidden lines Best natural position Orthographic View Selection Longest Dimension Most natural position Best shape description No hidden lines Orthographic View Selection Numbers • Another decision on view selection you need to make is how many views You usually not need more than three but you may only need one or two The following slides will show when to make a decision between one, and two view drawings 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 Precedence of Lines • In multiple view drawings, many times different line types will take up the same space, therefore, we have line precedence The following is an explanation of which lines exist over others – Object lines over hidden and center – Hidden over center – Cutting plane lines over center lines • The following slide will show an example Precedence of Lines An object line here takes prece over theprecedence center line over Howeve Object lines took draw short linessee beyond the hidden lines youthin would show there is in a cente from theobject hole to The center line underneath object line the top view would show the depth of the hole as well as the right side view References • Project Lead the Way www.myteacherpages.com/webpages/IED/files/ Sketching.ppt • 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 References • Johnson, Cindy M., Lockhart, Shawna D., Engineering Design Communication, Prentice Hall, 2000, ISBN 0201-33151-9 • Spencer, Henry Cecil, Dygdon, John Thomas, Novak, James E; Basic Technical Drawing 6th Edition; Glencoe McGraw Hill; New York, New York,1995, ISBN 0-02685660-3 Do you want to be a good sketcher? First Slide ... computer Freehand Sketching • Most original designs are first expressed on medium as a freehand sketch • Used for: – Amplifying and clarifying – Recording verbal explanations Technical Sketching. .. create instrument drawings • Freehand sketch should not mean crude and sloppy • Freehand sketch should be made with care and attention to proportion, clarity, and line widths Types of Sketches... Techniques • Sketching a Line Sketching Techniques • Sketching an Arc 1) Draw intersecting lines 2) Mark off equal distances 3) Draw line between marks Sketching Techniques • Sketching an Arc