Basic construction lec1

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Basic construction lec1

  1. 1. Lecture 1 Sunday, 09 September 2012 1 ENGINEERING GRAPHICS 1E9 Lecture 1: Introduction Lecturer: Dr. Bidisha Ghosh (bghosh@tcd.ie)
  2. 2. Course StructureGraphics• Hand Drawing (part 1) -Dr. B. Ghosh• Hand Drawing (part 2) -Dr. G. O’DonnellCAE• AutoCAD-Dr. S. Pavia
  3. 3. Assessment• Examination: 75% of the overall mark – 3 sections (A, B and C) – 2 questions per section – 3 questions to be answered, one from each section• Dr B. Ghosh : Sections A and B• Dr G. O’Donnell : Section C• Labs 25% - assessed by coursework – 10 % AutoCAD – 10% D.O. Tutorials Dr B. Gosh – 5 % D.O. Assignment Dr G. O’Donnell
  4. 4. Time Table Lecture Drawing Office practicals (AutoCAD laboratories for wks 11-12) Mon 10-11 a.m. Mon 2-5 p.m. (group C) Tues 2-5 p.m. (group D) Wedn 2-5 p.m.( group A) Fri 9 a.m.-12 noon (group B) Semester 1 Wk 1Mon 28th Sept BG - Wk 2 BG BG Wk 3 BG BG Wk 4 BG BG Wk 5 Holiday - Wk 6 GO’D GO’D Wk 7 Reading wk Reading wk Wk 8 GO’D GO’D Wk 9 BG BG Wk 10 SP - Wk 11 SP SP Wk 12 SP SP BG - Hand drawing I- Dr Bidisha Gosh GO’D - Hand drawing II- Dr Garret O’Donnell SP - Autocad – Dr Sara Pavía See JF timetable for venues
  5. 5. Lecture 1 Sunday, 09 September 2012 5 Syllabus – Hand Drawing 1 • Basic Construction • Orthographic Projections • Isometric Projections • Auxiliary Views • Perspective
  6. 6. Lecture 1 Sunday, 09 September 2012 6 Evaluation • Examination (Sections A & B) (2/3 of the total examination marks) • Continuous Assessment (10% of the total course marks) – four drawing office tutorials
  7. 7. Lecture 1 Sunday, 09 September 2012 7 Aim of the Course • Knowledge of engineering drawing instruments • Understanding and interpretation of technical drawings • Ability to develop projections of a 3D object
  8. 8. Lecture 1 Sunday, 09 September 2012 8 Reference Books • Technical Draughtsmanship By Eanna O’Broin • Engineering Drawing with Worked Examples By M.A. Parker & F. Pickup • Technical Drawing By F. E. Giesecke, A. Mitchell, H. C. Spencer, I. L. Hill, J. T. Dygdon, J. E. Novak
  9. 9. Lecture 1 Sunday, 09 September 2012 9 Technical drawing is the language of engineers and designers Waterfall M. C. Escher
  10. 10. Lecture 1 Sunday, 09 September 2012 10 Topics of Interest • Drawing Instruments • Lines • Dimensioning • Basic construction
  11. 11. Lecture 1 Sunday, 09 September 2012 11 DRAWING INSTRUMENTS 1 1. Drawing Board
  12. 12. Lecture 1 Sunday, 09 September 2012 12 DRAWING INSTRUMENTS 2 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
  13. 13. Lecture 1 Sunday, 09 September 2012 13 DRAWING INSTRUMENTS 3 •Layout of a Drawing Sheet
  14. 14. Lecture 1 Sunday, 09 September 2012 14 DRAWING INSTRUMENTS 4 • Tee square/ Drafting Machine
  15. 15. Lecture 1 Sunday, 09 September 2012 15 DRAWING INSTRUMENTS 5 • Set squares (a pair)
  16. 16. Lecture 1 Sunday, 09 September 2012 16 DRAWING INSTRUMENTS 6 • Irregular/ French curves
  17. 17. Lecture 1 Sunday, 09 September 2012 17 DRAWING INSTRUMENTS 7 • Compasses • Divider • Protractor • Ruler/Scale • Pencil, Eraser
  18. 18. Lecture 1 Sunday, 09 September 2012 18 DRAWING LINES 1 TYPES OF LINES • 3 Main Types
  19. 19. Lecture 1 Sunday, 09 September 2012 19 DRAWING LINES 2 • Lines to aid understanding
  20. 20. Lecture 1 Sunday, 09 September 2012 20 DIMENSIONING 1 Dimension Lines (DL) Position of DL
  21. 21. Lecture 1 Sunday, 09 September 2012 21 DIMENSIONING 2 Alignment of DL DL of Small Features Dimensioning Angles Dimensioning Circles
  22. 22. Lecture 1 Sunday, 09 September 2012 22 DIMENSIONING 3
  23. 23. Lecture 1 Sunday, 09 September 2012 23 DIMENSIONING 4 Correct Practice of Dimensioning Drawing should only carry dimensions needed to manufacture
  24. 24. Lecture 1 Sunday, 09 September 2012 24 DRAWING LINES Drawing Parallel Lines
  25. 25. Lecture 1 Sunday, 09 September 2012 25 DRAWING LINES Drawing Perpendicular Lines
  26. 26. Lecture 1 Sunday, 09 September 2012 26 DRAWING LINES Bisection of A Line A B 1. Place your compass point on A and stretch the compass MORE THAN half way to point B. 2. With this length, swing a large arc that will go BOTH above and below segment AB. 3. Without changing the span on the compass, place the compass point on B and swing the arc again. The new arc should intersect the previous one above and below the segment AB. 4. With your scale/ruler, connect the two points of intersection with a straight line. 5. This new straight line bisects segment AB. Label the point where the new line and AB cross as C. 6. Segment AB has now been bisected and AC = CB.
  27. 27. Lecture 1 Sunday, 09 September 2012 27 DRAWING LINES Divide A Line into Multiple Sections 1. From one end of the given line AB (say, A) draw a line AC at a convenient angle 2. Using a scale/ruler divide the BC into the required number of parts making them of any suitable length. 3. Join the last point on line AC (say, C) to B 4. Draw construction lines through the other points on the line AB which are parallel to CB
  28. 28. Lecture 1 Sunday, 09 September 2012 28 DRAWING LINES Bisection of An Angle 1. Place the point of the compass on the vertex of angle BAC (point A). 2. Stretch the compass to any length so long as it stays ON the angle. 3. Swing an arc with the pencil that crosses both sides of angle ABC. This will create two intersection points (E and F) with the sides of the angle. 4. Place the compass point on E, stretch your compass to a sufficient length and draw another arc inside the angle - you do not need to cross the sides of the angle. 5. Without changing the width of the compass, place the point of the compass on F and make a similar arc. These two small arcs in the interior of the angle should be crossing each other. 6. Connect the point of intersection of the two small arcs to the vertex A of the angle with a straight line.
  29. 29. Lecture 1 Sunday, 09 September 2012 29 DRAWING LINES Find the Centre of an Arc 1. Select three points A, B and C on the arc and join AB and BC 2. Bisect AB and BC. 3. Fine the intersection point of the bisecting lines/bisectors. That is the centre of the arc.
  30. 30. Lecture 1 Sunday, 09 September 2012 30 DRAWING LINES Inscribe a Circle in a Triangle 1. Bisect angle ABC and angle BAC. 2. Fine the intersection point of the bisecting lines/bisectors. That is the centre of the circle. 3. The radius of the circle is the length of a perpendicular line on any of the sides of the triangle drawn from the centre of the circle.
  31. 31. Lecture 1 Sunday, 09 September 2012 31 DRAWING LINES Circumscribe a Circle on a Triangle 1. Bisect sides AC and BC. 2. Fine the intersection point of the bisecting lines/bisectors. That is the centre of the circle. 3. The radius of the circle is the length of a line joining any one of the vertices of the triangle to the centre of the circle.
  32. 32. Lecture 1 Sunday, 09 September 2012 32 Notes for Tutorials • The tutorials start next Monday in drawing office in museum building • Each tutorial is worth 2.5% • Bring your own drawing instruments • Drawing sheets will be provided Students will not be allowed in the tutorial without instruments

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