DRAWINGDescribes an object without having much vocabulary.

MACHINEMotion converter

MACHINE DRAWINGExplains the shape, size of a machine component/ machine assembly.

Standardization• To make drawings universally acceptable.• ANSI• ASME• BS• ISO• BIS• BIS – Bureau of Indian Standards. (Latest SP 46:2003)

Designation Size (L X W) in mm

A0 1189 X 841

A1 841 X 594

A2 594 X 420

A3 420 X 297

A4 297 X 210

Drawing sheet size

Border and FrameCenter marks are used to position a drawing when reproduced.Grid reference helps in easy location of drawing details.

Center mark

Drawing space

Frame

Grid reference

Drawing Instruments• Drawing pin• Drawing clip• Adhesive tape• Drawing Board• Pencils• Sharpener• Eraser• Ink pens• Drafter• Set squares• Protractor• French curves• Instrument box• Scales

Used for fixing drawing sheet

Methods of Drawing• 1) Pictorial representation– a) Isometric– b) Perspective– c) Oblique

• 2) Orthographic projection

Orthographic projection is used in engineering drawing

Various drawings

• Part drawings• Production drawings• Assembly drawings• Sub assembly drawings• Exploded drawings

Part drawingDrawings with complete dimensions.

Production drawingGives complete production details. In addition to dimensions, tolerances are specified.

Assembly drawingShows the position of each part with respect to each other.

Sub assembly drawingBig machines may have sub assemblies

Exploded drawingRepresent the pictorial view of each component of an assembly.

Installation drawings• Supplied by the manufacturer to the client for installation

purpose.

Tabular drawings• Used for standard components like washer, bolt, nut, etc..

Lines used in drawings

Continuous thick line

Continuous thin line

Dashed line

Centre line

Section line

Lettering• Guide lines are used for lettering. (Top and base lines)

• For small letters waist lines are used (at h/3).

• Four lines (waist and drop) are used letters like j, g, q, …

• Size of letters– Titles 10 to 15 mm– Short notes 5 to 8 mm– Long notes 3 to 4 mm

• Spacing between lines– 0.5h to 1.5h– 1h gives better appearance

h

• Line thickness of letters• Bold face 0.13h to 0.16h• Medium face 0.08h to 0.12h• Light face 0.05h to 0.07h

Basic dimensioning• Dimension provides the size of the component.• Dimension without tolerance is Basic dimension.• Classification of dimensions

– Functional – essential for the function of the object.– Non functional – Auxiliary – marked for information only.

Elements of dimensioning• Extension line• Leader line• Dimension line• Arrows• Dimensional values

Various dimensioning

Various dimensioning contd..

Various dimensioning contd..

Various dimensioning contd..

Various dimensioning contd..

Dimensioning curves

Various dimensioning contd..

Method of drawing• Orthographic projection is used.• True shape and size is visible in orthographic projection when

the object is parallel to the plane of projection.• First angle method is used.• Sectional views are used to show the inner details of an object.