ENGINEERING DRAWING VISUALIZATION Axonometric Oblique Projection Axonometric Projection

ENGINEERING DRAWING VISUALIZATION

Axonometric & Oblique Projection

Axonometric Projection Parallel & normal to picture plane B A Line of sight A C B D C D

Axonometric Projection Type of axonometric drawing Axonometric axis a 1. Isometric A A C b B B D D All angles are equal. c Axonometric axis a 2. Dimetric Two angles are equal. c b C Axonometric axis a 3. Trimetric b c None of angles are equal.

Oblique Projection Parallel & oblique to picture plane A Line of sight A B B C C D D

Oblique Projection Oblique drawing angle 30 o A 60 o 45 o B C A Type of Oblique drawing B D C 2) Cabinet 1) Cavalier D Full scale 45 o Half scale 45 o

Isometric Projection & Isometric drawing

Isometric Projection Rotate 45 about vertical axis Tilt forward (35 o 16’) All edges foreshorten about 0. 8 time.

Isometric Drawing Isometric drawing is a drawing drawn on an isometric axes using full scale. Isometric projection (True projection) Isometric drawing (Full scale) Forshorten Full scale

Positions of Isometric Axes Isometric axes can be arbitrarily positioned to create different views of a single object. Regular isometric Reverse axis isometric Long axis isometric View point is looking down on the top of the object. View point is looking up on the bottom of the object. View point is looking from the right (or left) of the object.

Distance in Isometric Drawing True-length distances are shown along isometric lines. Isometric line is the line that run parallel to any of the isometric axes. Nonisometric lines Isometric axes

Isometric Sketching

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

Sketch from an actual object STEPS 1. Positioning object. 2. Select isometric axis. 3. Sketch enclosing box. 4. Add details. 5. Darken visible lines. Note In isometric sketch/drawing), hidden lines are omitted unless they are absolutely necessary to completely describe the object.

Sketch from multiview drawing 1. Interprete the meaning of lines/areas in multiview drawing. 2. Locate the lines or surfaces relative to isometric axis.

Example 1 : Object has only normal surfaces Top Regular H Top View Front View W Bottom View H W Side D Side View D Reverse Front Bottom Side

D Example 2 : Object has inclined surfaces Nonisometric line y H q y x Front View x W

Example 3 : Object has inclined surfaces x C x B A B x x A y C B A Nonisometric line

Example 4 Regular x y C D B B F Front View A C A E Reverse D F E

Circle & Arc in Isometric In isometric drawing, a circle appears as an ellipse. Sketching Steps 1. Locate the centre of an ellipse. 2. Construct an isometric square. 3. Sketch arcs that connect the tangent points.

Circle & Arc in Isometric Four-centre method is usually used when drawn an isometric ellipse with drawing instrument. Sketching Steps 1. Locate the centre of an ellipse. 2. Construct an isometric square. 3. Construct a perpendicular bisector from each tangent point. 4. Locate the four centres. 5. Draw the arcs with these centres and tangent to isometric square.

Example 5

Irregular Curve in Isometric Steps 1. Construct points along the curve in multiview drawing. 2. Locate these points in the isometric view. 3. Sketch the connecting lines.

Oblique Sketching

Object Orientation Guidelines Place complex features (arc, hole, irregular shape surface parallel to frontal plane.

Object Orientation Guidelines The longest dimension of an object should be parallel to the frontal plane. GOOD WORSE

Object Orientation Guidelines Which orientation is better ?

Sketch from actual object ESTIMATE DEPTH ESTIMATE LINES D 45

Sketch from multiview drawing

Sketch from multiview drawing E D C B A

Oblique and Isometric Drawings GSMST

Cavalier Oblique • Front view true size • Receding Axis Angle (Normally 30°, 45° or 60°) is Variable • Depth dimension (receding axis) true size

Cabinet Oblique • Front view true size • Receding Axis Angle (Normally 30°, 45° or 60°) is Variable • Depth dimension (receding axis) half size

Side by Side Comparison Cavalier Oblique Cabinet Oblique

Which is the cube ?

Were you right?

Angles in Oblique • Angles in front view are drawn true size • Other angles must be located using coordinates • Appearance of angles may be distorted

Circles in Oblique • Drawn true size in front view • Drawn as ellipses on receding planes • Layout using a Rhombus

Cylinders in Oblique • Front and Back surfaces are circular • “Sides” are drawn as lines tangent to the front and back

Types of Axonometrics

Orientation of Pictorial Objects

Isometrics • • Axes equally separated (120°) H, W, and D measurements are true size along iso. axes Angles must be located by coordinates Circles appear as ellipses on all surfaces

Isometric Circles & Angles

Isometric Ellipses

Using the Ellipse Template

Drawing Rounded Corners

Construction of Cylinders • Lightly block in the cylinder

Construction of Cylinders • Lightly block in the cylinder • Sketch the upper and lower ellipses

Construction of Cylinders • Lightly block in the cylinder • Sketch the upper and lower ellipses • Connect the ellipses with Tangent lines

Construction of Cylinders • Lightly block in the cylinder • Sketch the upper and lower ellipses • Connect the ellipses with Tangent lines • Darken the lines

Isometric Drawing Exercise You will use two different lines to sketch objects: PConstruction lines are light lines sketched in as you initially draw the object. PDrawing lines are dark lines which may be used for the initial drawing or which may be created by neatly darkening a construction line.

Isometric Drawing Exercise To draw an isometric object using the box method, perform the following steps: Step 1: Draw a box around the object you wish to draw.

Isometric Drawing Exercise Step 2: Draw a box on your paper, in the same proportions as the box you drew on the object, 1½ to 2 times larger than the original box. Proportional box Original box

Isometric Drawing Exercise Step 3: Look at the front side of the object. Which surface touches the outside of the box? Step 4: Draw the surface on your box using drawing lines.

Isometric Drawing Exercise Step 5: Look at the top of the object. Which surface touches the outside of the box? Step 6: Draw the surface on your box using drawing lines.

Isometric Drawing Exercise Step 7: Look at the right hand side of the object. Which surface touches the outside of the box? Step 8: Draw the surface on your box using drawing lines.

Isometric Drawing Exercise Step 9: Complete the box by drawing in the “third lines”. You may wish to draw construction lines then neatly cover the construction lines with drawing lines.