GENERAL DRAWING 2

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ENGINEERING { GEOMETRICAL & MACHINE } DRAWING !!!

HINTS / BREIF PROCEDURES

1]INTERSECTION OF SURFACES OF SOLIDS [ INTERPENETRATION OF SOLIDS ]:

  1. DRAW THE PROJECTIONS OF BOTH THE GIVEN SOLIDS, IN THEIR RELATIVE POSITIONS. ONE OF THE GIVEN SOLID MAY BE IMAGINARY, JUST FOR MAKING A HOLE IN THE OTHER SOLID.IF ONE SOLID,THE PENETRATING SOLID, IS HORIZONTAL, BUT HAS ITS AXIS PERPENDICULAR TO THE V.P.,THEN ITS LINE VIEW[AXIAL VIEW] IS IN THE FRONT VIEW ITSELF, and HENCE NO NEED TO DRAW THE SIDE VIEW OF BOTH THE SOLIDS, UNLESS ASKED. BUT, IF THE SOLID's AXIS IS PARALLEL TO BOTH THE REF.PLANES[HP & VP], THEN , WE HAVE TO DRAW THE SIDE VIEW SHOWING ITS AXIAL VIEW , WHCH IS ITS LINE VIEW. {LINE VIEW IS A VIEW , IN WHICH, THE LATERAL SURFACE OF THE SOLID IS SEEN AS A LINE-----As CIRCLE IN THE CASE OF CYLINDER & As A POLYGON IN THE CASE OF PRISM. IN THE LINE VIEW , THE AXIS IS SEEN AS A POINT, SINCE WE SEE ALONG ITS AXIS, REDUCING ITS LATERAL SURFACE AS A MERE LINE--WHICH IS THEN TREATED AS A CUTTING LINE,representing the cutting surface of the solid. SO, LINE VIEW OF THE CONEs, PYRAMIDs & SPHERES ARE NOT POSSIBLE, AS THEIR SURFACES ARE CONTINUOUSLY INCLINING & CURVING and not along / parellel to the axis.
  2. HENCE, this "LINE-VIEW" procedure is not completely valid for cases involving both the solids as cones or pyramids or spheres , in any combination.
  3. DRAW or IDENTIFY A VIEW WHERE , THE LATERAL SURFACE OF ONE OF THE SOLIDS IS SEEN AS A LINE [i.e.,LINE-VIEW]. IF A SOLID LIKE CYLINDER or PRISM , IS INCLINED, THEN AUXILIARY VIEW OF THE SAME MAY HAVE TO BE DRAWN LOOKING ALONG ITS AXIS, TO GET ITS "LINE-VIEW".
  4. IN THE ABOVE "LINE-VIEW",WHICH CAN BE SIDE VIEW ,or FRONT VIEW or TOP VIEW OF BOTH THE SOLIDS , MARK THE CRITICAL POINTS OF INTERSECTION w.r.to. BOTH THE SOLIDS, WHERE EXTREMITIES,LATERAL / SLANT EDGES INTERSECT. IDENTIFY SHARP POINTS OF INTERSECTION , WHERE A (CURVED)SURFACE INTERSECTS AN EDGE OF A PRISM or PYRAMID. ALSO RECOGNISE WHETHER WE GET TWO SETS OF CURVES(2 SETS OF POINTS) or A SINGLE CURVE( ONLY ONE SET OF POINTS)-----i.e.,we get 2 curves , if one of the solids is completely penetrating inside the other solid. IN ADDITION TO THE ABOVE CRITICAL POINTS, MARK ADDITIONAL CURVE-DEFINING POINTS OF INTERSECTION, ONLY IF ONE OF THE SOLIDS IS EITHER A CONE or A CYLINDER.
  5. THROUGH ALL THE ABOVE POINTS OF INTERSECTION, DRAW or IDENTIFY SURFACE LINES OF THE CUT SOLID SURFACE LIKE GENERATORS, SLANT / LATERAL EDGES or IMAGINARY SURFACE LINES or CIRCUMFERENCIAL SURFACE LINES { CSL s}. THESE CSLs ARE NOTHING BUT IMAGINARY CO-AXIAL CIRCULAR SURFACE LINES {in CONES}/ POLYGONAL SURFACE LINES{in PYRAMIDS}.THE CSLs ARE SEEN AS STRAIGHT LINES PARALLEL TO THE BASE LINE OF THE SOLID.
  6. DRAW OR IDENTIFY ALL THE ABOVE SURFACE LINES IN OTHER VIEWS,IN THEIR RELATIVE POSITIONS.
  7. PROJECT / TRANSFER ALL THE POINTS OF INTERSECTION ON TO THE CORRESPONDING SURFACE LINES (GENERATORS or CSLs) IN THE OTHER VIEWS IN PROPER SEQUENCE/ ORDER. NAME THE POINTS OF INTERSECTION USING, preferably NORMAL/ARABIC NUMERALS(1,2,3,...) or ROMAN NUMERALS (I, II, III, ...).
  8. JOIN ALL THE ABOVE POINTS OF INTERSECTION BY PROPER LINES IN THE ORIGINAL SEQUENCE(FREE-HAND CURVE , IF ONE OF THE SOLIDS IS CURVED--CONE / CYLINDER ; STRAIGHT LINES OF INTERSECTION , IF BOTH THE SOLIDS ARE POLYHEDRA--PYRAMID/PRISM.
  9. VISIBILITY :
  1. PENETRATING SOLID: WHATEVER IS HIDDEN INSIDE THE PENETRATED SOLID, or HIDDEN BEHIND THE OPAQUE SURFACES OF THE PENETRATED SOLID/ITSELF, IS HIDDEN.ALL OTHER EXISTING EDGES/ OUTLINES ARE VISIBLE.
  2. LINES / CURVES OF INTERSECTION: FIRST OF ALL, IDENTIFY ALL THE VISIBLE POINTS OF INTERSECTION , WHICH EVER ARE DIRECTLY ACCESSIBLE BY THE OBSERVER's SIGHT RAYs WITHOUT ANY OBSTRUCTION. THEN , JOIN ALL THESE VISIBLE POINTS OF INTERSECTION, BY THE VISIBLE LINES OF INTERSECTION[DARK-THICK type of LINE : FOR DETAILS REFER GENERAL DWG.].All other points of intersection are to be joined by Dark-Dashed-Thick type of line :FOR DETAILS of types of LINES etc.,REFER GENERAL DWG.].Visible lines of intersection meet visible lines/edges of the solid(s).
  3. PENETRATED SOLID: The edges/surface lines , whichever are CUT-OFF / REMOVED / PUNCHED-OFF by the penetrating solid, are NOT TO BE DRAWN as either visible or hidden lines.Only the remaining & existing (i.e.,not imaginary)lines are to be considered for the visibility.Whatever surface line of the penetrated solid is visible to the observer without anybody's obstruction , is to be drawn Dark-Thick ; all other existing hidden lines are to be drawn Dark-Dashed-Thick. If the penetrating solid is removed, leaving a hole inside the penetrated solid , then , visibility increases, since, the hiding surfaces of the penetrating solid are removed & all boundary lines exposed to the environment are always become visible.
  4. ALL THE DRAWN VIEWS MUST BE CLEAR WITH ALL THE GIVEN DIMENSIONS AND NAMES.
  5. DEVELOPMENT OF SURFACES OF (CUT) SOLIDS:
  1. DRAW THE PROJECTIONS OF THE GIVEN SOLIDS AS DESCRIBED IN THE CASE OF INTERSECTION OF SURFACES.
  2. DRAW or IDENTIFY "LINE-VIEW" .
  3. MARK CRITICAL POINTS OF INTERSECTION & OTHER POINTS OF INTERSECTION.
  4. IN THE "LINE-VIEW", DRAW or IDENTIFY SURFACE LINES OF THE CUT SOLID, THROUGH ALL THE ABOVE POINTS OF INTERSECTION.
  5. DRAW DEVELOPMENT OF THE SOLID, FIRST AS IF IT IS NOT CUT. THEN, MARK ALL THE EFFECTIVE SURFACE LINES IN THEIR TRUE RELATIVE POSITIONS, w.r.to THE REGULAR(Equally divided ) surface lines of the solid, whose surface is to be developed.Use only true lengths to draw developments.
  6. TRANSFER ALL THE POINTS OF INTERSECTION , IN PROPER ORDER, TO THE CORRESPONDING SURFACE LINES , VIA THE TRUE LENGTH LINE, SO THAT THE POINTS COME ON THE APPROPRIATE CSL., IN THEIR TRUE RELATIVE POSITIONS.
  7. JOIN ALL THE POINTS OF INTERSECTION BY APPROPRIATE DARK THICK LINES OF INTERSECTION.
  8. DARKEN ALL THE EXISTING SURFACE LINES IN THE DEVELOPMENT , EXCEPT THE IMAGINARY LINES LIKE GENERATORS, CSLs .
  9. OPEN THE DEVELOPMENT FROM THE STARTING POINT OF THE SHORTEST PATH, IF IT IS GIVEN.
  10. IN THE CASE OF REVERSE PROBLEMS OF DEVELOPMENT , FIRST DRAW THE DEVELOPMENT, AND SHOW THE GIVEN PATH/ LINE/ CURVE ON THE DEVELOPMENT. MARK THE POINTS OF INTERSECTION ALONG THE PATH/ LINE , WITH THE HELP OF SOME REGULAR AND SPECIAL SURFACE LINES OF THE SOLID.
  11. TRANSFER THE ABOVE POINTS OF INTERSECTION , VIA THE TRUE LENGTH LINE, TO THE CORRESPONDING SURFACE LINE IN THE REQUIRED ORTHOGRAPHIC PROJECTIONS OF THE SOLID.
  12. SHOW ALL THE NAMES OF POINTS OF INTERSECTION & THE GIVEN DIMENSIONS as well as the used TRUE dimensions / Calculations.

2] MACHINE ELEMENTS

  1. RIVETTED JOINTS: PROPORTIONS TO BE REMEMBERED:
  1. GIVEN MAIN PLATE THICKNESS, t in mm
  2. DIAMETER OF THE RIVET, d = sq.root of "t" [ROUND IT OFF TO A HIGHER/ STDD.VALUE ].
  3. RIVET HEAD DIA. Dh =1.6 d
  4. RIVET HEAD THICKNESS, t h = 0.7 d
  5. PITCH OF RIVETS IN A ROW, p = 3d
  6. MARGIN FROM THE CENTER OF RIVET, m c = 1.5 d
  7. ROW PITCH , p r = 2 d + 6 mm [ IN CASE OF CHAIN TYPE OF JOINT ] ; p r = 2 d [ IN CASE OF ZIG-ZAG TYPE OF JOINT ]
  8. THE ABOVE ARE VALID FOR BOTH LAP AS WELL AS BUTT JOINTS.
  9. FOR ONLY BUTT JOINTS , CALCULATE
  1. CENTRAL ROW PITCH , p rc = 2 m c = 3 d
  2. SINGLE COVER/ STRAP (plate) THICKNESS , t c1 = 1.125 t
  3. COVER/ STRAP (plate) THICKNESS , in case of double strap Butt Joint, t c2 = 0.8 t

DRAW SECTIONAL FRONT VIEW & TOP VIEW OF THE RIVETTED JOINT , SHOWING THE CUTTING PLANE and THE DIMENSIONS/ PROPORTIONS.

  1. SCREWED / THREADED FASTENERS: REMEMBER PROPORTIONS ONLY FOR STANDARD NUT, BOLT & WASHER -- OTHERS ARE NOT SO IMPORTANT.,EXCEPT FOR THEIR PROFILE/PROPORTIONATE SHAPES and THEIR NOMENCLATURE.
  2. FREE HAND WRITTEN & DRAWN NOTES ON MACHINE ELEMENTS :
    1. TYPES OF IMPORTANT JOINTS USED IN ENGINEERING:TYPES of JOINTS.jpg
    2. weld-symbols.jpg
    3. IS convention of Threads.jpg
    4. M& Sq Thread Profiles.jpg
    5. BSW,SELLERs & ACME.jpg
    6. Buttress&Knuckle.jpg
    7. Bolts1.jpg
    8. Bolts2.jpg
    9. Bolts3.jpg
    10. Washers.jpg
    11. Bolt in Position & Screw Thread.jpg
    12. Tapped Hole.jpg
    13. Bolts-nuts.jpg
    14. Nuts1.jpg
    15. Nuts2.jpg
    16. Wing & Knurled Nuts.jpg
    17. Setscrew & STUDs.jpg
    18. Setscrews1.jpg
    19. Setscrews2.jpg

3]ISOMETRIC PROJECTIONS & VIEWS:

  1. FOR ISOMETRIC PROJECTIONS USE ISOMETRIC SCALE [ ISOMETRIC LENGTHS ] FOR ALL DIMENSIONS EXCEPT FOR DRAWING THE SPHERE, WHERE USE TRUE LENGTH RADIUS(R).
  2. FOR ISOMETRIC VIEWS or DRAWINGS , USE NATURAL SCALE [ TRUE LENGTHS ] FOR ALL , INCLUDING FOR THE LOCATION OF THE CENTER OF THE SPHERE, EXCEPT FOR THE RADIUS OF THE SPHERE, WHICH IS TO BE TAKEN AS R ' = 11/9 (R).
  3. FIRST CORRELATE THE GIVEN ORTHOGRAPHIC VIEWS WITH EACH OTHER , and SPLIT-UP THE WHOLE OBJECT/ MACHINE CASTING INTO SOME SIMPLE REGULAR PARTS / DETAILS, LIKE PRISMATIC BASE PLATE, HOLLOW CYLINDER WITH A COUNTER BORE, TRIANGULAR RIB/WEB, BOSS,C'SUNK HOLE, TAPPED HOLE(M24), KEY-WAY / SLOTS, CHAMFERED / FILLETED BLOCKS,PCD ON A FLANGE, SAW-CUT , ETC,.
  4. FOR EACH & EVERY SPLIT-UP PART or DETAIL , DRAW ISOMETRIC VIEW/ PROJECTION ; CONSIDERING SAME DIRECTION FOR THE Z-DIMENSION , AS PER THE ORIGIN FOR THE WHOLE OBJECT [ IF WE SEE THE OBJECT FROM THE RIGHT HAND SIDE , THEN , TAKE Z-DIMENSION ALONG 30 0 LINE ON THE RIGHT HAND SIDE ] i.e., FOR RIGHT HAND ORIGIN , TAKE RIGHT HAND SIDE Z-DIMENSION & HENCE THE X-DIMENSION IS TO BE TAKEN ON THE LEFT HAND SIDE ALONG THE 30 0 LINE .
  5. AFTER ASSEMBLING ALL THE INDIVIDUAL VIEWS FOR EVERY PART/ DETAIL, IN ITS RELATIVE POSITION & DIRECTION, APPLY OVERALL VISIBILITY and INTEGRATION WHOLLY AS A SINGLE CASTING/MOULD.
  6. NO NEED OF SHOWING ANY DIMENSIONS , EXCEPT FOR SPHERE 's CENTRE LOCATION & ITS RADIUS.
  7. HOWEVER , RETAIN ALL CONSTRUCTION LINES , BUT LIGHTLY.
  8. NO NEED OF HIDDEN DETAILS IN ISOMETRIC VIEWS/PROJns.

4]OBLIQUE VIEWS:

  1. JUST LIKE IN THE CASE OF ISOMETRIC VIEWS, STUDY THE GIVEN VIEWS, & SPLIT-UP THE WHOLE OBJECT INTO SIMPLE PARTS/DETAILS .
  2. OBSERVE FOR CURVED or INCLINED / Specially Profiled surfaces----so that , these can be taken on UN-DISTORTED SURFACE , whose dimensional directions [ like X & Y ] can be taken at 90 0 to eachother.,and the third dimension [ like Z ] can be taken along the RECEDING / OBLIQUE AXIS { R . A }, which is normally at 45 0 ,w.r.to the Horizontal line. But,some times ,you may be asked to take either 30 0 or 60 0 . If you take 30 0 , then , more of the side surface is shown. If 60 0 is taken , then , more of the top surface is shown w.r.to the side surface.
  3. The R.A. can be other than the Z axis. IT can be X axis, and the un-distorted surface axes can then be Y & Z --out of which , Y is normally / prefarably VERTICAL.
  4. Just like in the case of Isometric views, assemble all the individual split-up parts/ details in their relative positions and directions .

5] [Principal] MISSING VIEWS:

Just like in the case of Isometric/ Oblique View construction; study thoroughly & split-up the whole object in to simple parts .

Draw only the REQUIRED Views -- but , don't simply copy the given views to project physically the required views. Don't show all the projector lines , except the extreme & critical projector lines.

Follow the Machine Drawing conventions/Standards , like not hatching the ribs/ WEBS ,when cut parallel to the major area of the web[reducing the thickness in to half.]

For each & every part , draw its missing view in its relative position and direction.

Apply overall Visibility & integration before hatching and Dimensioning, especially the missing view.

6] AUXILIARY ( Missing ) VIEWS:

Just like in the case of principal Missing view construction , look in the auxiliary direction to draw the auxiliary view , which is missing in the auxiliary direction.

Normally , the purpose of drawing the auxiliary views is to show the True Shape of the inclined surface of a part in the given object., by looking in the auxiliary inclined direction , perpendicular to the inclined surface whose True Shape is to be seen in the Auxiliary View.

Aux. Front View is projected from TopView, showing the vertical "Y" dimensions as TL.,generally measured perpendicularly from the ground/ reference line.

Aux. Top View is projected from Front View , showing the horizontal "Z" dimensions as TL.,generally measured perpendicularly from the central reference line.

If , the Aux. Top View is projected from the Side ( Elevation)View , then , since it is projected from the X-points of the side view , the Aux. Top View shows "X= TL" w.r.to a cientral reference line.

In all the above cases , the auxiliary reference plane/ Xa Ya line , generally divides the TL [ true length ] into two halves.

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