Computer Aided Design(CAD)

Engineering Drawing Standards - BS308

Orthographic Projection

Orthographic Projection

Orthographic Projection

SOME TECHNICAL TERMS (page 1)

Flange

Keyway

Keyway

Key

Taper

Shaft

Shoulder

Bush Web Bore Boss Collar Spoke Rim Hub

Pulley

Rib

Bracket

base

Fillet

Table

Slot

Spotface

Counterbore Lug Countersink

Dowel Blind hole

Tee slot Chamfer

Spigot

Recess

SOME TECHNICAL TERMS (page 1)

CAN YOU DETERMINE THE PROJECTION SYSTEM USED? (first or third angle?)

CAN YOU IDENTIFY THE TYPES OF HOLES ABOVE?

Projection Symbol – How to Draw

COMMON LINE TYPES (page 5)

� 1. Continuous Thick (0.5mm) TYPE A

� 2. Continuous Thin (0.25mm) TYPE B

� 3. Dashed Thin (0.25mm) TYPE E

� 4. Chain Thin (0.25mm) TYPE F

LINETYPES

� Hidden

� Center

� Hatch

� Outlines

� Text

� Dimension Lines

� Leader Lines

Leader Lines

� To show where dimensions or notes apply.

� Always end in arrowheads or dots.

� Arrowheads touch and stop on a line

� Dots should be within the outline of the object.

� Long or intersecting leader lines should not be used.

General Points on Drafting

� Arrows:

� Triangular and Solid

� Length = 3 x width

� Arrows on Dimensions -> 3-5mm Long

� Arrows showing direction of view -> 7-10mm Long

� Text Height = Not less than 3mm.

� Underlining of text is not recommended.

� Notes of a general character to be grouped together.

General Points on Drafting

Commonly Accepted Symbols and Abbreviations

� AF

� ASSY

� CRS

� CL

� CHAM

� CH HD

� CSK

� CSK HD

� CBORE

� CYL

� DIA

� DRG

� EQUI SP

� EXT

� FIG.

� HEX

� HYD

� INSUL

� INT

� LH

� LG

� MATL

� MAX

� MIN

Commonly Accepted Symbols and Abbreviations

� NO.

� O/D

� PATT NO.

� PCD

� RAD

� R

� REQD

� RH

� RD HD

� SCR

� SH

� SK

� SPEC

� SR

� SFACE

� SQ

� STD

� THD

� TYP

� UCUT

� VOL

� WT

SCREW THREAD - TERMS

SCREW THREAD - TYPES

SCREW THREAD - External

NOTE:

Inner lines are Type

2 Lines (Continous Thin Lines)

SCREW THREAD - Internal

NOTE:

Inner lines are Type

2 Lines (Continous Thin Lines)

SCREW THREAD - Internal

SECTIONS AND SECTIONAL VIEWS

(page 12 BS308)

� Hatching is Drawn with Type B (Continuous Thin) Lines, equally spaced at 45º.

� Preferably not less than 4mm Apart

� With very small parts, never less than 1mm

� On adjacent parts, alternate the direction of Hatching.

� Correct Section Line – Type F (Chain Thin)

SECTIONS AND SECTIONAL VIEWS

SECTIONS AND SECTIONAL VIEWS

SECTIONS AND SECTIONAL VIEWS

SECTIONS AND SECTIONAL VIEWS

SECTIONS AND SECTIONAL VIEWS

(page 15 BS308)

� PARTS NOT NORMALLY SECTIONED WHEN THE CUTTING PLANE PASSES LONGITUDINALLY THROUGH:

FASTNERS (bolts, nuts) SHAFTS, RIBS, WEBS, SPOKES of WHEELS etc.

SECTIONS AND SECTIONAL VIEWS

(page 15 BS308)

FASTNERS AND SHAFT

NOT

SECTIONED

WEB NOT

SECTONED

OFFSET SECTIONSECTION IN MORE THAN 1 PLANE

EXTRA RESOURCE INFORMATION

� DeGarmo, E. P., et al., Materials and Processes in Manufacturing, 8th Ed., Maxwell Macmillan, 1997