Lesson: Detail Drawings: Communicating with EngineersContributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Educational Standards :
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Introduction/Motivation (Return to Contents)
Engineers do not manufacture their own creative work, but typically communicate their ideas to highly trained machinists and manufacturers, who then construct the various components that make up the designs. Engineers also must present their designs in a way that is understood by engineers in different countries and cultures. Engineers also leave a legacy of creative thought through their designs. To preserve this technology from one generation to the next, it must be well-documented. How would you do this? How do engineers do this? A detail drawing is a tool used by engineers to communicate their designs to manufacturers and to preserve their work for future generations.
To facilitate the sharing of design information, engineers have created uniform standards, protocols and tools. One of these standards is called the ANSI Y14.5, which is a description for how to create a "detail drawing." A detail drawing is a two-dimensional representation of an engineer's design that contains all the information needed to precisely reproduce it. Detail drawings are especially useful when an engineer wants to manufacture his or her design. Given a proper detail drawing, a manufacturer knows exactly how to create a part without the need for additional verbal explanation from the engineer. The detail drawing stands on its own, so to speak, and provides a record or archive of the engineer's precise intent.
(Show students example detail drawings and describe information from the Lesson Background section. Use the Detail Drawing Visual Aids, which provides Figures 1-3, in a format suitable for overhead projection or handouts. Then administer the attached quiz and conduct the associated activity.)
Lesson Background & Concepts for Teachers (Return to Contents)
A "detail drawing" is a drawing of a single component, assembly of multiple parts, or an entire system of assemblies. A detail drawing provides complete and precise descriptions of a part's dimensions, shape and how it is manufactured. A detail drawing should be concise, in that it conveys only the information needed to create the part. Information such as the exact size, type of material, finish, tolerance and any special shop instructions that are necessary to create the part are included its detail drawing.
Detail drawings are created on standard paper sizes. The "North American Standard Paper Size" is specified by the ANSI Y14.5 standard and is used in the US. Figure 1 shows the different North American Standard paper sizes. The smallest size is designated by the letter "A" and is the size of a typical sheet of notebook paper (8 ½ x 11 inch). The largest size is "E," which is equivalent to 16 sheets of notebook paper.
An engineer "scales" very large or small objects in his or her drawings. For example, the components that make up a 1-inch microrobot are too small to draw to scale due to feature sizes that are not easily seen unmagnified. An appropriate scale, say 1/10 inch = 1 inch, is chosen to convey the necessary details, and then an appropriate paper size is chosen. The scale of the drawing is noted in the title block.
The following information should be present on a detail drawing:
Figure 2 is an example of a detail drawing that contains all the necessary information to create this component. Note the following from this drawing:
In a detail drawing, views are included to clearly describe a three-dimensional object through the medium of two-dimensional paper. The front view is the first view that is chosen and is the only view that is arbitrary, that is, the engineer defines (decides) which view will be the front view. All other views are based off of the chosen front view. Views are positioned on the paper according to the convention illustrated by Figure 3.
Note that the views are obtained by rotating the front view. For example, the front view is rotated 90° to the left to obtain the left view, the front view is rotated 90° to the right to obtain the right view, the right view is rotated 90° to the right to obtain the back view, and so on. Note that the isometric view is obtained by considering the component within a cubical room looking towards the opposite, lower corner from an upper corner. Views need not be labeled as they are in Figure 3; their locations in the detail drawing relative to the front view defines each view. Sketching the views by hands takes practice. The associated Drawing Designs in Detail activity provides an opportunity for students to practice drawing the standard views.
The convention used in Figure 3 is called "third angle projection," which is used by North American manufacturers. Another convention, called "first angle projection," is used in Europe and Asia.
Vocabulary/Definitions (Return to Contents)
Associated Activities (Return to Contents)
Attachments (Return to Contents)
Assessment (Return to Contents)
Lesson Summary Assessment
Quiz: After the lesson, administer the attached Detail Drawings Quiz to students, which asks them to identify drawing view perspectives and explain why the rules and procedures for creating detail drawings are so comprehensive and thorough. Review their answers to gauge their comprehension of the subject matter.
ContributorsBenjamin S. Terry, Stephanie Rivale, Denise W. Carlson
Copyright© 2010 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.