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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