machine drawing introduction

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Computer Aided Machine Drawing Sub Code 10ME36A / 10ME46A IA Marks 25 Hrs/week 04(1 Hrs. Theory & 3 Hrs Practical) Exam Hours 03 Total Lecture Hrs 52 Exam Marks 100

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Computer aided Machine drawing

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  • Computer Aided Machine Drawing

    Sub Code10ME36A / 10ME46AIA Marks25Hrs/week 04(1 Hrs. Theory & 3 Hrs Practical)Exam Hours03Total Lecture Hrs 52Exam Marks100

  • UNIT - 1

    Sections of Solids: Sections of Pyramids, Prisms, Cubes, Tetrahedrons, Cones and Cylinders resting only on their bases (No problems on axis inclinations, spheres and hollow solids). True shape of sections.

    Orthographic Views: Conversion of pictorial views into orthographic projections. of simple machine parts with or without section. (Bureau of Indian Standards conventions are to be followed for the drawings) Hiddenline conventions. Precedence of lines.PART-A

  • UNIT 2

    Thread Forms: Thread terminology, sectional views of threads. ISO Metric (Internal & External) BSW (Internal & External) square and Acme. Sellers thread, American Standard thread.

    Fasteners: Hexagonal headed bolt and nut with washer (assembly), square headed bolt and nut with washer (assembly) simple assembly using stud bolts with nut and lock nut. Flanged nut, slotted nut, taper and split pin for locking, counter sunk head screw, grub screw, Allen screw.PART-A

  • PART-BUNIT 3

    Keys & Joints : Parallel key, Taper key, Feather key, Gibhead key and Woodruff key

    Riveted Joints: Single and double riveted lap joints, butt joints with single/double cover straps (Chain and Zigzag, using snap head rivets). Cotter joint (socket and spigot), knuckle joint (pin joint) for two rods.UNIT - 4Couplings: Split Muff coupling, Protected type flanged coupling, pin (bush) type flexible coupling, Oldham's coupling and universal coupling (Hooks' Joint)

  • PART C

    Assembly Drawings1. Plummer block (Pedestal Bearing)2. Rams Bottom Safety Valve3. I.C. Engine connecting rod4. Screw jack (Bottle type)5. Tailstock of lathe6. Machine vice7. Tool Head of a shaper

  • TEXT BOOKS:1. 'A Primer on Computer Aided Machine Drawing-2007, Published by VTU, Belgaum.2. 'Machine Drawing', N.D.Bhat & V.M.PanchalREFERENCE BOOKS:1. 'A Text Book of Computer Aided Machine Drawing', S. Trymbaka Murthy, CBS Publishers, New Delhi, 20072. 'Machine Drawing, K.R. Gopala Krishna, Subhash Publication

  • Scheme of ExaminationInternal assessment: 25 MarksTwo questions to be set from each Part-A, Part-B and Part-CStudent has to answer one question each from Part-A and Part-B for 20 marks each.

    One question from Part-C for 60 marks.PART-A 1 x 20 = 20 MarksPART-B 1 x 20 = 20 MarksPART-C 1 x 60 = 60 Marks Total = 100 Marks

  • IntroductionTOPICS OF ENGINEERING GRAPHICS

  • 1660306030Aligned SystemUnidirectional SystemSystem of Placing DimensionsCommonly used in Engineering Drawing.Commonly used on large drawing aircrafts, automobiles

  • Dimensioning Techniques

  • The ways of Placing the Dimensions in a Series603520Chain Parallel

  • The ways of Placing the Dimensions in a Series901530301501560453030Combined Progressive

  • 15 When the space is too narrow, the arrow-head may be placed outside. Also a dot may be used to replace an arrow-head.

    The various methods of dimensioning different sizes of circles are as follows: 101015151010302020Arcs of circles should be dimensioned by their respective radii. R3R20R8R6

  • Radii of a spherical surface and square cross section of a rod is shown as below:Sphere R20SQ24Angular dimension may be given as follows:20o25o120o4045Length of ChordLength of Arc

  • Method of dimensioning of Chamfer:245o Dimensioning of Tapered Surface:LhH1:20Slope or Taper = (H-h)/L

  • SCALING OF A DRAWING(AS PER BUREAU OF INDIAN STANDARDS FOR ENGINEERING DRAWING.)RECOMMENDED SCALES1. FULL SCALE e.g. 1: 1In certain cases the engineering components may be very large or very small for drawing purposes,hence the corresponding scale may be preferred from the following2. REDUCED SCALE e.g. 1:2, 1:2.5, 1:5, 1:10, 1:20, 1:15, 1:100, 1:200, 1:500, 1:1000 3. ENLARGED SCALE e.g. 50:1, 20:1, 10:1, 5:1, 2:1

  • Length of the drawing Actual length of objectR.F. =(representative fraction) SCALING OF A DRAWING

  • SYMBOLS USED ON ENGINEERING DRAWING SHEETM/c. PARTS ARE NEVER ASSUMED IN SECOND OR IN FOURTH QUADRANT,

    AS THE VIEWS MAY OVERLAP ON ONE ANOTHER ABOVE XY OR BELOW XY RESPECTIVELY

  • Two concepts when specifying dimensionsSizeLocation Basic dimensioning practiceDimension linesProvide information on the size of the objectExtension linesLines that extend from the points to which the dimension or location is to be specifiedLines are drawn parallel to each other with dimension line placed between themDimensioning

  • Notations of DimensioningArrow-head

  • Leaderdimension linecenterlineextension lineBasics of dimensioning practice

  • Line typesCenter linesHidden lines

  • Fundamentals of Machine Drawing

  • Represent a 3d object in 2d.Show a scaled representation of an object.Easily capture all geometric features of an object.Convey all required information that will allow an object to be produced from raw material.Fundamentals of Machine Drawing

  • Representing 3d objects in 2dIsometric projection: One view of an object in which the three axes of space (x,y,z) appear equally foreshortened.Orthographic projection: Multiple views of an object from points of view rotated about the object's center through increments of 90. The views are positioned relative to each other.

  • Representing 3d objects in 2dOrthographic projection can provide six planar views of an object. Show multiple views to convey every detail.Hidden linesare short dashed

  • Orthographic projection: each view can be thought of as projections of an object onto the sides of a glass box.Front viewTop viewSide viewOrthographic projections

  • Representing 3d objects in 2d

  • Isometric projections are useful for assembly drawingsIsometric projection with dimensions.Nice isometric sketches work well.Assembly drawing