Freehand Sketching

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

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

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!

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

Types of Sketches

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.

Freehand Sketching Freehand sketches are not sloppy!

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

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

Freehand Sketching Shape the sketches Add appropriate details Darken object lines

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

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.

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

Line types

Examples of Good Freehand Sketching Technique

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!

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

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

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.

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

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

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

Horizontal line Vertical line

Nearly vertical inclined line

Nearly horizontal inclined line

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

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

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.

Arc Method 1 : Starting with a square

Arc Method 2 : Starting with a center line

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

Example

Example

Example