1. Freehand Sketching

2. Freehand drawing Example
The lines are sketched without using instruments other than pencils and erasers.
Example

3. Freehand Sketching Ideation – Integral to the design process
Generation of design concepts to solve a design problem
Usually freehand sketching is used to explore, study and communicate these design concepts
Even today, and for the foreseeable future, many great design ideas are communicated via freehand sketching
The “BEST” design engineers can immediately communicate an idea via a freehand sketch

4. Freehand Sketching Required Do not use Pencil, Paper and Eraser
Straight edges, templates, compasses etc.
They slow down the process and defeat the purpose of fast communication of ideas!

5. Freehand Sketching Sketches are planned Visualize the sketch
Size of paper & scale
Orientation of the object
Minimum detail to communicate the idea
Type of sketch
Oblique
Isometric
Orthographic

6. Types of Sketches

7. Types of Sketches Oblique
Advantage: one true face
Disadvantage: not “photorealistic”
Isometric (a type of axonometric drawing) & Perspective
Advantage: easy to visualize the object
Disadvantage: no true face
Multi-View (orthographic)
Advantage: true faces
Disadvantage: hard to visualize
Isometric, oblique, and perspective
sketches are methods of showing
the object in a single view.

8. Freehand Sketching
Freehand sketches are not sloppy!

9. Freehand Sketching
When possible use the grid on your engineering paper!

10. Freehand Sketching Outline the sketch Use light lines
Show major edges and boundaries and then add small details

11. Freehand Sketching Shape the sketches Add appropriate details
Darken object lines

12. Freehand Sketching Fundamental Rule of Sketching
Maintain Proportion
Hints: use standard techniques to draw lines and arcs
Lines
Locate a start “dot”
Locate an end “dot”
Put pencil on start dot, look at the end dot and smoothly move pencil toward the end dot

13. Freehand Sketching Circles (arcs)
Draw light horizontal and vertical lines that intersect at the center
Lightly mark the radius on the lines
Connect the radius marks with arcs to complete the circle
See Step-by-Step 3.1& 3.3 on pages 60 & 62.

14. Construction Lines Light and thin lines
Serve as path for final straight lines
Intersection of construction lines specify the length of the final lines
Points marked by the intersection of construction lines serve as guides for sketching of arcs and circles
Guide the proportion of the sketch

15. Line types

16. Examples of Good Freehand Sketching Technique

17. Oblique Sketching
Step 1 – Draw the horizontal and vertical construction lines which outline the basic shape of the main face - “Blocking in”
Step 2 – Sketch the face of the part
Step 3 – Sketch receding construction lines at 30 or 45 degrees
Step 4 – Sketch- in and darken the lines outlining the part – Done!

18. Isometric Sketching
Step 1 – Construct a horizontal line, two lines at 30 degrees above the horizontal and a vertical line through their intersection
This defines the isometric axes used to draw the sketch

19. Isometric Sketching
Step 2 – Sketch in a box to “block-in” the front face and the other faces follow
Step 3 – Sketch the outline of the front face in it’s “block” and the other faces follow
Work parallel to the isometric axes

20. Isometric Sketching
1. Place the object in the position which its shape and features are clearly seen.
2. Define an isometric axis.
3. Sketching the enclosing box.
4. Estimate the size an and relationship of each details.
5. Darken all visible lines.

21. Isometric Sketching STEPS 1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.

22. Isometric Sketching STEPS 1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.

23. Straight Line 1. Hold the pencil naturally.
2. Spot the beginning and end points.
3. Swing the pencil back and forth between the points, barely
touching the paper until the direction is clearly established.
4. Draw the line firmly with a free and easy wrist-and-arm motion

24. Horizontal line
Vertical line

25. Nearly vertical inclined line

26. Nearly horizontal inclined line

27. Small Circle Method 1 : Starting with a square
1. Lightly sketching the square and marking the mid-points.
2. Draw light diagonals and mark the estimated radius.
3. Draw the circle through the eight points.
Step 1
Step 2
Step 3

28. Small Circle Method 2 : Starting with center line
1. Lightly draw a center line.
2. Add light radial lines and mark the estimated radius.
3. Sketch the full circle.
Step 1
Step 2
Step 3

29. Large Circle
Place the little finger (or pencil’ s tip) at the center as a pivot, and set the pencil point at the radius-distance from the center.
Hold the hand in this position and rotate the paper.

30. Arc
Method 1 : Starting with a square

31. Arc
Method 2 : Starting with a center line

32. Steps in Sketching
1. Block in main shape.
2. Locate the features.
3. Sketch arcs and circles.
4. Sketch lines.

33. Example

34. Example

35. Example