Engineering Drafting is explored by the use of ACAD 2002. In Lesson 12 we begin the task of engineering the simple spur gear, which is animated and rendered above.As With Cams there will be a specifications page, a table that will contain all of the formula's to engineer the gear. After all the calculations are made we can begin to draw the gear as outlined in this lesson. The technique for drawing spur gears is the same technique used in Board Drafting but CADD is far more accurate and fast in the drafting of the Gear.

Each of the gears drawn in this section of Engineering Drafting will be extruded as a 3d model and each student will be required to animate that model as a "gif" animated image.

Connecting Your Learning

As you work your way through this lesson, you should reflect on the following questions:

What is the function of a Gear?
What 3 pieces of information are needed to create a spur gear?
What is the difference between a drive and a driven gear?
What is a gears purpose in an automobile engine?
What is a gears purpose in a transmission?

The State of Arizona has assembled Drafting standards to make sure that Instruction is thorough and well thought out by the instructor. By clicking on the hyperlink below will upload to your browser window the entirety of these standards. The standards that are addressed in this lesson are below the hyperlink.

1.0 USE BOARD DRAFTING EQUIPMENT, INSTRUMENTS AND MEDIA.

• 1.1 Analyze Drawing surfaces for Drafting
• 1.6 Demonstrate Sheet Setup skills

2.0 DEMONSTRATE SKETCHING, LETTERING, AND LINE SKILLS.

• 2.1 Demonstrate freehand sketching skills for drafting applications.
• 2.2 Demonstrate lettering skills.
• 2.3 Demonstrate line work.

6.0 DEMONSTRATE GEOMETRIC CONSTRUCTIONS

• 6.1 Measure Geometric Constructions.
• 6.2 Develop Geometric Constructions.

8.0 APPLY BOARD DRAFTING SKILLS TO COMPUTER-AIDED DESIGN/DRAFTING (CADD)

• 8.1 Demonstrate computer skills for a CADD system.
• 8.2 Create dimensional CADD entities.
• 8.3 Create 3 dimensional CADD drawings.

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The State of Arizona has also assembled Math standards and many of these apply directly to the vocational subject area of Drafting. Drafting is a very precise discipline and the use of mathematics is integral to design and manufacturing. Below are the math standards that are involved in this lesson

1M-P1. Compare and contrast the real number system and its various subsystems with
regard to their structural characteristics

• PO 2. Compare subsets of the real number system with regard to their properties
  (commutative, associative, distributive, identity, inverse and closure properties)

1M-P2. Construct, interpret and demonstrate meaning for real numbers and absolute

• PO 3. Solve real-world distance problems using absolute value
• PO 4. Determine, among the solutions to a real-world problem, which, if any, is reasonable
• PO 2. Define absolute value as the distance from the origin

4M-P1. Interpret and draw three-dimensional objects

• PO 1. Sketch prisms, pyramids, cones, cylinders and spheres
• PO 2. Classify prisms, pyramids, cones, cylinders and spheres by base shape and lateral surface shape.
• PO 3. Recognize the three-dimensional figure represented by a two-dimensional drawing.
• PO 5. Make a model of a three-dimensional figure from a two-dimensional drawing and make a two-dimensional representation of a three-dimensional object (models and representations include scale drawings, perspective drawings, blueprints or computer simulations)

4M-P4. Deduce properties of, and relationships between, figures from given
assumptions

• PO 1. Find similarities and differences among geometric shapes and designs using a given attribute (e.g., height, area, perimeter, diagonals and angle measurements)
• PO 2. Identify arcs, chords, tangents and secants of a circle
• PO 3. State valid conclusions using given geometric definitions, postulates and theorems
• PO 4. Represent pi as the ratio of circumference to diameter
  

Lesson Objectives

1. Draw using ACAD 2002 the Spur Gear from the table of Engineering Specifications.
2. Use the Array command to array the teeth that are constructed from these specifications.
3. Use the trim command to trim all skew lines and create a region.
4. Extrude the region into a 3d gear and subtract a cylinder from its center, creating an axis of rotation.
5. Use the Rotate3d command and orient the extruded model in Plan View and scale to 1/2.
6. Setting the view to Render in Photo Real and applying and adjusting mapping materials in ACAD.

Key Terms

"click on the key on any of these terms and it will hyperlink to the course glossary"

involute	spur gear	idler gear	dimetric pitch
pressure angle	addendum	dedendum	OD
PD	Root Diameter	Circular Pitch	Circular Thickness

 

 

Instruction

Your Text Book and Reading Assignments

Summary and Assessment