There are many techniques used in technical illustration. In this lesson will be practicing the methods of drawing various types of holes in models: countersunk, counter bore, bead up or flanged out holes. There are various commands in Autocad for accomplishing drawing these kinds of holes both isometrically and three dimensionally.

The ellipse is used extensively in illustrating these various kinds of holes. In this lesson you will be drawing various models that illustrate the aforementioned hole styles.

 

Connecting Your Learning

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

Why are counter bores used?
What parts illustrate countersunk holes?
Does the chamfer command in autocad produce countersunk holes ?

 

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 a counter bore isometrically and in 3d..
2. Use the chamfer command in CADD to create a countersunk hole.
3. Section a sphere.
5. Orient a 3d image to an isometric perspective.

Key Terms

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

isometric	fillet	ellipse	orthographic
counter bore	chamfer	bead-up	ellipse
countersunk	sections	glass box	assembly drawing
Iso Ellipse	proportion	ellipse	Angstrom

 

Instruction

The following are the models that will be used for Lesson 11:

• Lesson 11a: [The Model as seen below "Box and Busing ortho"].
• Lesson 11b: [The Model as seen below "Box Cover ortho].
• Lesson 11c: [An Isometric Assembly Drawing exploded and unexploded]
• Lesson 11d: [A 3d assembly drawing exploded and unexploded]

  I will explain this further in the lesson 10 media disc. Please insert the media disk and listen to lesson 11.

*Note: The Lessons are best viewed with real player and you can download the latest version by clicking on the words real player.

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Summary and Assessment