ENGINEERING DRAWING & GRAPHICS Lecture 1: Introduction By Engr. Sajjad Ahmad

Assessment Marks Examination: 30 % mid term 50% final term Assignments & Quizzes 20 %

Syllabus Introduction Orthographic Projections Loci of points and Generated Curves Development of solids Intersection of surfaces Projection of solids Free hand sketches

Recommended Books Engineering drawing by ND Bhatt Engg Drawing by AC Parkinson Technical Graphics Communication By Bertoline Wiebe, Miller. Mohler, Irwin McGraw-Hill 1997 Practical Geometry & Engineering Graphics By Abbot. Engineering Graphics By Craft, Meyers & Boyer Technical Graphics Communication, 3rd Edition By Gary R. Bertoline and Eric N. Wiebe; McGraw-Hill Mathematical Elements for Computer Graphics By D.F. Rogers and J.A. Adams; McGraw-Hill 1976

Importance of Engg Drawing “a picture is worth a thousand words” In engineering, a good drawing is worth even more than a thousand words

Importance of Engg Drawing Engineering drawings are important in conveying useful information to other engineers and machinists Allow the readers to visualize what the proposed product would look like Provide information on dimensions and material used to make the proposed product Provide views from the top, the side, and the front

Aim of the Course Knowledge of engineering drawing instruments Understanding and interpretation of technical drawings Ability to develop projections of a 3D object

Technical drawing is the language of engineers and designers Waterfall M. C. Escher

Topics of Interest Drawing Instruments Lines Lettering & Dimensioning

Drawing Board DRAWING INSTRUMENTS 1 Layout of a typical drawing shet should be same as the background of this presentation. Nameplate at the bottom right corner.

Drawing Sheets A Series Formats (mm) A0 841 × 1189 A1 594 × 841 A2 DRAWING INSTRUMENTS 2 Drawing Sheets A Series Formats (mm) A0 841 × 1189 A1 594 × 841 A2 420 × 594 A3 297 × 420 A4 210 × 297 A5 148 × 210 A6 105 × 148 A7 74 × 105

Layout of a Drawing Sheet DRAWING INSTRUMENTS 3 Layout of a Drawing Sheet Layout of a typical drawing sheet

Tee square/ Drafting Machine DRAWING INSTRUMENTS 4 Tee square/ Drafting Machine

DRAWING INSTRUMENTS 5 Use of T Square

DRAWING INSTRUMENTS 6 Set squares (a pair)

DRAWING INSTRUMENTS 7 Use of set squares

DRAWING INSTRUMENTS 8 Use of set squares

Irregular/ French curves DRAWING INSTRUMENTS 9 Irregular/ French curves

Use of French Curves The french curve is DRAWING INSTRUMENTS 10 Use of French Curves The french curve is used to draw a smooth line through predetermined points.

Compasses Divider Protractor Ruler/Scale Pencil Different Grades DRAWING INSTRUMENTS 11 Compasses Divider Protractor Ruler/Scale Pencil Different Grades 6B,5B,4B,3B,2B,B,H,2H,....9H

TYPES OF LINES 3 Main Types DRAWING LINES 1 HIDDEN LINES WHERE EXTENSION OF VISIBLE LINES SHOULD HAVE A GAP BETWEEN THE TWO Lines Single centre line for longitudinal view and crossed centre lines for cross sectional view

Lines to aid understanding DRAWING LINES 2 Lines to aid understanding

LETTERING Most common font used in drafting is

Approved Gothic lettering for Engineering Drawings

Reasons for using single-stroke Gothic lettering Saves time in production Easy to read and provides drawing consistency Easier to learn and use

Lettering is drawing, not writing

Recommended Strokes for Vertical Uppercase Letters

Lettering Rules The type of lettering recommended by ANSI for mechanical drafting is single stroke gothic (vertical freehand lettering). The minimum recommended lettering size on engineering drawings is .125 inches (1/8”). All dimension numerals, notes and other lettered information should be the same height except for titles, drawing numbers and other captions. Titles and subtitles, for example, may be 0.5 inch (1/2”) and.25 inches (1/4”) high respectively.

Lettering Rules Continued The composition or spacing of letters in words and between words in a sentence should be such that the individual letters are uniformly spaced with approximately equal background areas. This requires the letters such as I, N or S be spaced slightly father apart from their adjacent letters than L, A, or W. A minimum recommended space between letters in words is approximately .0625 inches (1/16”). The space between words in a note or sentence should be about the same at the height of the letters. The horizontal space between sentences in a note or paragraph should be equal to twice the height of lettering.

Spacing of Lettering

Lettering Rules Continued All notes should be lettered horizontally on the sheet. Use H, HB pencils for lettering. Try them all, but use the one that gives you the best results. Many drafters prefer using a .5 mm automatic pencil for lettering.

Lettering Rules Continued Place a clean paper under your hand when lettering to prevent smudging. As a rule of thumb, curved letters can be placed close together and straight letters should be placed further apart.

Use a Piece of Clean Paper to Prevent Smudging

Spacing of Fractions and Decimals

DIMENSIONING 1 Dimension Lines (DL) Position of DL

Alignment of DL DL of Small Features Dimensioning Angles Dimensioning Circles

DIMENSIONING 3

Correct Practice of Dimensioning Drawing should only carry dimensions needed to manufacture

Rules for Dimensioning Dimensions should be placed outside the views Dimension line should not cross each other As far as possible dimension should not be shown between dotted lines Dimension line should be placed at least 8 mm from the outlines and from one another Dimension figures are placed perpendicular to dimension line Dimension figure should be easily readable from bottom and right edge of paper

Assignment Get your instruments sorted- buy them or borrow them