Orthographic Writing

TOPICS Views selection Alignment of views Orthographic writing steps Basic dimensioning Tangency and intersections

View Selection

VIEW SELECTION STEPS 1. Orient the object to the best position relative to a glass box. 2. Select the front view. 3. Select adjacent views.

STEP 1 : Orient the Object The object should be placed in its natural position. The object should present its features in actual size and shape in orthographic views. GOOD NO !

STEP 2 : Select a Front View The object’s longest dimension should be presented as a width. First choice Second choice Waste more space GOOD Inappropriate

STEP 2 : Select a Front View The adjacent views that are projected from the selected front view should appear in its natural position. Inappropriate

STEP 2 : Select a Front View Choose the view that have the fewest number of hidden lines. GOOD Inappropriate

STEP 3 : Select an Adjacent View Choose the view that have the fewest number of hidden lines. GOOD Inappropriate GOOD Inappropriate

STEP 3 : Select an Adjacent View Choose the minimum number of views that can represent the major features of the object. Necessary Hole’s location can be specified on the same view. Easy to understand Difficult to interprete. Necessary

STEP 3 : Select an Adjacent View Choose the views that are suitable to a drawing space. POOR Not enough space for dimensioning.

STEP 3 : Select an Adjacent View Choose the views that are suitable to a drawing space. GOOD

      Example : View selection mislead to… Size description H W F.V. H W D F.V. & T.V. Three views F.V. & R.S.V.    Size description    Shape description

ONE-VIEW DRAWING Flat part having a uniform thickness. Unnecessary These 2 views provide only information about the part thickness !

ONE-VIEW DRAWING Cylindrical-shaped part. Unnecessary Repeat ! Infer from CL Unnecessary

TWO-VIEW DRAWING There exists an identical view. Repeat ! Unnecessary

TWO-VIEW DRAWING The 3rd view has no significant contours of the object. Unnecessary

TWO-VIEW DRAWING The 3rd view has no significant contours of the object. Unnecessary

Alignment of Views

ORTHOGRAPHIC VIEWS 1st angle system Right Side View Front View Top View

Orthographic Writing Steps

WRITING STEPS 1. Select the necessary views 2. Layout the views. 3. Project the views. 4. Dimension the views.

1. SELECT THE NECESSARY VIEWS TOP FRONT

2. LAYOUT THE VIEWS 1:1 A4 Choose an appropriate scale 152 64 25 45

PROJECT THE VIEWS

DIMENSION THE VIEWS x x z y y x x y y PART NAME NOTES 1. Dimensions in millimeters. 2. ….

Basic Dimensioning

COMPONENTS 1. Extension lines 2. Dimension lines 3. Leader lines 10 27 10 Drill, 2 Holes R16 2. Dimension lines 3. Leader lines 4. Dimension numbers 17 5. Local notes 43

Tangencies and Intersections

TANGENT & INTERSECTION

TANGENT & INTERSECTION No line is formed when curved surface tangent to a plane surface. Line is formed when curved surface intersects a plane surface. No line tangent intersect No line tangent intersect

TANGENT & INTERSECTION limiting element tangent tangent tangent plane intersect

TANGENT & INTERSECTION No line tangent tangent tangent tangent No line tangent No line

FILLET AND ROUND To draw the arc, we must find the location of the center of that arc. How do we find the center of the arc?

To draw an arc of given radius tangent to two perpendicular lines arc radius r r r

To draw an arc of given radius tangent to two perpendicular lines arc radius r center of the arc Starting point Ending point

To draw an arc of given radius tangent to two lines arc radius r r r + +

To draw an arc of given radius tangent to two lines arc radius r T.P.1 T.P.2

To draw a line tangent to a circle at a point on the circle Given C

To draw a line tangent to a circle from a point outside the circle Given mark a tangent point C

When circle tangent to other circle Tangent point R1 C1 R2 C2 R1 + R2 The center of two circles and tangent point lie on the same straight line !!!

To draw a circle tangent to two circles I + Given + C2 + C1 Example

To draw a circle tangent to two circles I Given Two circles and the radius of the third circle = R + + C2 C1

To draw a circle tangent to two circles I Given Two circles and the radius of the third circle = R R + R2 center of the arc R + R1 R2 C R R1 + + C2 C1 Repeat

When circle tangent to other circle Tangent point R1 R2 C1 C2 R2  R1 The center of two circles and tangent point must lie on the same straight line !!!

To draw a circle tangent to two circles II + Given + C2 + C1 Example

To draw a circle tangent to two circles II Given Two circles and the radius of the third circle = R + + C2 C1

To draw a circle tangent to two circles II Given Two circles and the radius of the third circle = R R R2 R1 + + R – R2 C2 C1 R – R1 C Repeat

To draw a circle tangent to two circles III Given Two circles and the radius of the third circle = R R2 R1 + C2 + C1 R + R2 R – R1 C

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