Engineering Sketching Techniques “A picture says a thousand words” Allyson White STEM Lab 2011

THE DESIGN PROCESS Define Goals Test Plan Build Improve Generate Ideas

Learning Goals Recognize the three basic styles of engineering sketches. Understand why a detailed sketch is a powerful communication tool. Be able to accurately sketch an object using isometric, orthographic, and oblique design methods.

Why? Troubleshooting: ◦ Sketches allow engineers to see each part of a product before a prototype is developed Communication: ◦ Sketches reveal details of a product; size shape, and features, quickly and accurately.

5 Minutes to Prove It! This activity will illustrate how much better a sketch communicates an idea than a verbal description. 1.Draw a large rectangle on your paper. 2.Draw 2 smaller rectangles inside the large rectangle. 3.Draw a circle inside one of the small rectangles. 4.Compare your design to your neighbors.

Are all the designs the same? Does your design match mine?

Isometric Projection Isometric projections show three sides of an item in proportional dimensions. ◦ All vertical lines are vertical ◦ All horizontal lines are drawn at a 30° angle. Picture Source: Total Fabrication, Retrieved from: a2388c8eb190/1/905_draw_t3.zip/2_draw/draw_t3/h tm/draw3_2_2.htm a2388c8eb190/1/905_draw_t3.zip/2_draw/draw_t3/h tm/draw3_2_2.htm

Isometric Projection- Dimensions Clearly label important dimensions. Label contains numbers only Unit of measurement is located bottom of design Do not label more than is necessary to build the item. Illustration created with Google SketchUp 6®

Orthographic Projection Orthographic sketches represent 3D items in multiple 2D drawings. Top, front, bottom, and side views may be used. The general rule is to use only the views necessary to show the details of the item.

The Glass Box Imagining your item in a glass box is a good way to mentally separate the faces of the item before beginning an orthographic sketch. Image source: Martin (n.d.)

Orthographic Example Illustration created with Google SketchUp 6® Top Side left The edges of each view line up as though “the box” had been unfolded.

Oblique Projection Oblique projections are perhaps the simplest of the 3D sketch techniques. 1. Sketch the front of the item. 2. Project lines back from the vertices at 45° angles. These lines are drawn at one-half scale. 3. Connect the lines to form the visible portion of the back of the item. 1.

Computer Aided Design (CAD) Software packages range from the simple such as the ModelSmart program we use, Google SketchUp (free to download) to the very complex.

Manual Design There are many specialized tools for manually creating technical designs. ◦ 45°/90° triangle ◦ 30°/60° triangle ◦ Protractor ◦ Square ◦ Ruler ◦ Compass ◦ Specialized grid paper ◦ And many more...

Independent Practice Choose a common object that is easily identified. Create 3 projections of the object. ◦ Isometric ◦ Orthographic ◦ Oblique Use the classroom drafting tools. Use the specialized grid paper. Drafting tools may be signed out during pm homeroom and must be returned during the next morning’s am homeroom

Resources for Students Sokolowski, G. (2004) Orthographic Projection #1, Wisc-Online. Ryan, V. (2011) Oblique projections: Ryan, V. (2011) Isometric projections:

Standards Alignment Standard 11: Students will develop abilities to apply the design process. ◦ [ H] Apply a design process to solve problems in and beyond the laboratory-classroom. ◦ [J] Make two-dimensional and three-dimensional representations of the designed solution. Standard 17: Students will develop an understanding of and be able to select and use information and communication technologies. ◦ [K] The use of symbols, measurements, and drawings promotes clear communication by providing a common language to express ideas.

Resources EST Foundations (2006), Topic 3- Engineering Sketching. Retrieved from: Google Inc., (2007) Google SketchUp Version Retrieved from: Martin Suzette (n.d.) Technical and architectural design one, Orthographic projection. Retrieved from: Ryan, V. (2011) Isometric projections: technologystudent.com. Retrieved from: Ryan, V. (2011) Oblique projections:, technologystudent.com. Retrieved from: Sokolowski, G. (2004) Orthographic Projection #1, Wisc-Online. Retrieved from: Total Fabrication, (n.d.) What is isometric drawing?. Retrieved from: a2388c8eb190/1/905_draw_t3.zip/2_draw/draw_t3/htm/draw3_2_2.htm a2388c8eb190/1/905_draw_t3.zip/2_draw/draw_t3/htm/draw3_2_2.htm