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Freehand Sketching

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Freehand Sketching. Create freehand sketches using the correct sketching techniques. Explain the difference between axonometric and oblique projection. Explain the difference between isometric projection and isometric sketch (or draw ) . - PowerPoint PPT Presentation

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Page 1: Freehand Sketching

Freehand Sketching

Page 2: Freehand Sketching

Objectives

Explain the difference between axonometric and oblique projection.

Explain the difference between isometric projection and isometric sketch (or draw).

Create an isometric and oblique sketches from an actual object and given multiview drawing.

After completing this chapter, the students will be able to

Create freehand sketches using the correct sketching techniques.

Page 3: Freehand Sketching

Topics

Freehand sketch

Pictorial projections- Axonometric- Oblique

Isometric sketch

Oblique sketch

Page 4: Freehand Sketching

Freehand Sketching

Page 5: Freehand Sketching

Basic geometry

Straight line : Horizontal, vertical and Inclined.

Arc & Circle

Page 6: Freehand Sketching

Sketching Lines1. 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.

Page 7: Freehand Sketching

Sketching Lines

Page 8: Freehand Sketching

Sketching Arc

Method 1 :Starting with asquare

Method 2 :Starting with acenter line

Page 9: Freehand Sketching

Sketching a Small CircleMethod 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

2/3

1/3

Page 10: Freehand Sketching

Method 2 : Starting with center line

Step 1 Step 2 Step 3

1. Lightly draw a center line.

2. Add light radial lines and mark the estimated radius.

3. Sketch the full circle.

Sketching a Small Circle

Page 11: Freehand Sketching

1. Place the pencil’ s tip at the center as a pivot, and set the pencil point at the radius-distance from the center.

2. Hold the hand in this position and rotate the paper.

Sketching a Large Circle

Page 12: Freehand Sketching

PictorialProjections

Page 13: Freehand Sketching

Pictorial Projection

AB

CD

Parallel & normalto picture plane

Lineof

sightA

B

CD

A

BC

D

Lineof

sight

Parallel & obliqueto picture plane

A

D

C

B

Axonometric Projection Oblique Projection

Page 14: Freehand Sketching

Axonometric Projection

AB

CDLine

ofsight

AB

CD

Page 15: Freehand Sketching

Axonometric ProjectionType of axonometric drawing

a

b c2. Dimetric Two angles are equal.

b

a

c3. Trimetric None of angles are equal.

a

b c1. Isometric All angles are equal.

AB

CDA

B

C

D

Axonometric axis

Axonometric axis

Axonometric axis

Page 16: Freehand Sketching

A

BC

D

Lineof

sight

Oblique Projection

A

D

C

B

Page 17: Freehand Sketching

Oblique Projection

A

D

C

B

B

C D

A

Oblique drawing angle

30o45o 60o

Type of Oblique drawing

45o 45o

1) Cavalier 2) Cabinet

Fullscale Half

scale

Page 18: Freehand Sketching

Isometric projectionvs.

Isometric sketch

Page 19: Freehand Sketching

Isometric Projection

Rotate 45about vertical axis

Tilt forward (35o16’)

All edges foreshortenabout 0.8 time.

Page 20: Freehand Sketching

Isometric sketchIsometric sketch is an isometric view that is drawnin full size.

Isometric projection(True projection)

Isometric drawing(Full size)

Forshorten

Full scale

Page 21: Freehand Sketching

Orientation of Isometric AxesIsometric axes can be arbitrarily oriented to create different views of a single object.

Regularisometric

Reverse axisisometric

Long axisisometric

View point is lookingdown on the top ofthe object.

View point is lookingup on the bottom ofthe object.

View point is lookingfrom the right (or left)of the object.

Page 22: Freehand Sketching

Distance in Isometric Sketch

Isometric line is the line that run parallel to any of the isometric axes.

Isometric axes

True-length distances show along isometric lines.

Nonisometric lines

Page 23: Freehand Sketching

Isometric Sketching

Page 24: Freehand Sketching

2. Define an isometric axis.

3. Sketching the enclosing box (or cylinder).

4. Estimate the size an and relationship of each details.

5. Darken all visible lines.

1. Place the object in the position which its shape and features are clearly seen.

Sketch from an actual object

Page 25: Freehand Sketching

STEPS

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing box.

4. Add details.

5. Darken visible lines.

Sketch from an actual object

Page 26: Freehand Sketching

1. Positioning object.

2. Select isometric axis.

3. Sketch enclosing box.

4. Add details.

Note In isometric sketch/drawing), hidden lines are omittedunless they are absolutely necessary.

STEPS

5. Darken visible lines.

Sketch from an actual object

Page 27: Freehand Sketching

1. Interprete the meaning of lines/areas in multiview drawing.

2. Locate the lines or surfaces relative to isometric

axis.

Sketch from multiview drawing

Page 28: Freehand Sketching

Front View

Top View

Side View

Example 1 : Object has only normal surfaces

Bottom ViewBottom

FrontSide

SideFront

TopRegular

Reverse

WD

H

H

DW

Page 29: Freehand Sketching

Example 2 : Object has inclined surfaces

W

H

q

D

y

x Front View

y

x

Nonisometric line

Page 30: Freehand Sketching

A

A

B

B

C D

ED

EF

F

x

y

Front View

Regular

C

Example 4

Reverse

Page 31: Freehand Sketching

Isometric ellipseIn isometric drawing, a circle appears as an ellipse.

2. Construct an isometric square.

3. Sketch arcs that connect the tangent points.

Sketching Steps

1. Locate the center of an ellipse.

Page 32: Freehand Sketching

3. Construct a perpendicular bisector from each tangent point.

4. Locate the four centers.

5. Draw the arcs with these centers and tangent to isometric square.

Sketching Steps

Four-center method is usually used when drawn an isometric ellipse with drawing instrument.

2. Construct an isometric square.

1. Locate the center of an ellipse.

Isometric ellipse

Page 33: Freehand Sketching

Example 5

Page 34: Freehand Sketching

Irregular Curve in Isometric

1. Construct points along the curve in multiview drawing.

2. Locate these points in the isometric view.

3. Sketch the connecting lines.

Steps

Page 35: Freehand Sketching

ObliqueSketching

Page 36: Freehand Sketching

Object Orientation Guidelines

Complex features (arc, hole, irregular shape surface) are placed parallel to frontal plane.

Page 37: Freehand Sketching

The longest dimension of an object should be parallel to the frontal plane.

GOOD

WORSE

GOOD

WORSE

Object Orientation Guidelines

Page 38: Freehand Sketching

Which one is better ?

Object Orientation Guidelines

Page 39: Freehand Sketching

D

45

ESTIMATE DEPTH ESTIMATE LINES

Sketch from actual object

Page 40: Freehand Sketching

Sketch from multiview drawingExample 1

Page 41: Freehand Sketching

Sketch from multiview drawingExample 1

Page 42: Freehand Sketching

AB

C

D

E

Sketch from multiview drawingExample 2

Page 43: Freehand Sketching

AB

C

D

E

Sketch from multiview drawingExample 2

Page 44: Freehand Sketching

AB

D

E

C

Sketch from multiview drawingExample 2

Page 45: Freehand Sketching

AB

D

E

C

Sketch from multiview drawingExample 2