1. “One picture is worth a thousand words.”
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Sketching Practice
“One picture is worth a thousand words.”
Design and Modeling
© 2011 Project Lead The Way, Inc.

2. What is the purpose of sketching?
Think through a design
Share ideas
Visualize

3. Sketching Uses
Brainstorm
Communicate ideas
Document measurements

4. Advantages of sketching
It is convenient to sketch
Inexpensive
Easy way to communicate

5. Pictorial Sketches Show shape of object Show height, width, and depth
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Pictorial Sketches
Show shape of object
Show height, width, and depth
Common types:
Isometric
Perspective
Pictorial drawings show the shape of an object viewed by the human eye. Pictorial sketches are sketches that show height, width, and depth all in one view. Common types of pictorial drawings are isometric and perspective.

6. Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Isometric Sketch
Width and depth lines are drawn at 30° from the horizon line.
One view shows height, width, and depth.

7. 3D Sketching Techniques
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
3D Sketching Techniques
Isometric Grid Paper
A technique you can use when making an isometric sketch is to use isometric grid paper. This helps with determining the right angle for your sketch. You can also create a more professional look to your sketch by turning the paper over and drawing the sketch on the white side of the sheet but still utilizing the grid. Your finished product will look cleaner if it is on the white side of the paper.

8. Thumbnail Isometric Sketch
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Thumbnail Isometric Sketch
Copy and label this cube on your isometric axis.

9. Isometric Thumbnail Sketch
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Isometric Thumbnail Sketch
Additive and Subtractive 3D sketch
Follow the steps in your activity to complete this drawing on the isometric graph paper.
An isometric sketch shows an object in which the width and depth are projected at 30 degree angles from the horizontal axis. The height, width, and depth values are all at the same scale.

10. Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Perspective
Perspective is a way to draw that shows a view of the object in the most realistic way.
Vanishing points are used to guide the lines in the object to the horizon line or the horizontal line you see at your line of sight.

11. One-Point Perspective
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
One-Point Perspective
Vanishing Point (VP)
All lines in the depth project to one point (the vanishing point).
The location of the vanishing point is based on your line of sight.
Copy this one-point perspective sketch onto your activity. Label the front, top, and right side.
This is an example of one point perspective. Notice that all lines in the depth project to one point, the vanishing point. The location of the vanishing point is based on your line of sight.

12. Two-Point Perspective
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Two-Point Perspective
VP1
VP2
In two-point perspective, the width lines converge on one vanishing point (VP1), and the depth lines converge on the other vanishing point (VP2).
Copy this two-point perspective onto your activity sheet. Label the top, front, and side.

13. Orthographic (Multiview Drawings)
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Orthographic (Multiview Drawings)
Pictorial sketches help engineers explain ideas and communicate to the customer what the final part will look like. Unfortunately, pictorial drawings have some disadvantages. Foreshortened views and distorted features do not allow for accurate prototyping. In order for parts to be accurately depicted, you typically need views that directly portray each surface. The arrows represent the line of sight associated with each view. Any object possesses six views. Notice the similarities between the front and back, the right and left, the top and bottom views.

14. Orthographic (Multiview) Sketching
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Orthographic (Multiview) Sketching
It is used to show true size and shape.
Each view is adjacent to the other as if unfolded from a 3D shape.
Notice the top view is directly above the front with the right side view directly to the right of the front.
In order to obtain these straight line views, we have a type of drawing called orthographic projection, also known as multiview drawing. Orthographic projection is a way to project a view based on a line of sight that is perpendicular to that view.

15. Orthographic (Multiview) Sketching
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Orthographic (Multiview) Sketching
Copy this orthographic sketch onto your activity sheet. Label the top, front, and right side.
Don’t forget the hidden lines.
Note the orientation of the views. Each view is adjacent to the other as if they were unfolded from a 3D shape. Front, top, and right side views are used most often.

16. Orthographic – View Selection
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Orthographic – View Selection
Characteristics for selecting the front view
Best shape & details
Longest dimensions
Fewest hidden lines
Most natural position
Finding the best view of a part can be difficult. Two or more sides may seem to be the best choice for the front view. Consider these four main details when selecting the front view. First, which side shows the best shape or details of the object? Which side shows the longest dimensions of the object? Which side shows the fewest hidden lines? Which side shows the most natural position of how the object will be used?
Which view do you think should be the front?

17. Precedence of Lines Object lines exist over hidden and center lines.
Sketching Practice
PLTW Gateway®
Unit 1 – Lesson 1.4 – Sketching and Dimensioning Techniques
Precedence of Lines
Example 1
Object line over
hidden lines
Object lines exist over hidden and center lines.
Hidden lines exist over center lines.
Example 2
Object line
over center line
In multiple view drawings, different line types often compete for space; therefore, we have line precedence.
Object lines exist over hidden and center lines. In example 1, the object lines take precedence over the hidden lines that you would see from the hole. In example 2, an object line takes precedence over the center line. However, we draw short thin lines beyond the object to show that a center line exists underneath the object line.
Hidden lines exist over center lines. (no example of this shown)