GENERAL ENGINEERING DRAWING - HINTS BY PROF. FARUQH

[ FOR F.E.-II 4 -YEAR COURSE OF UNIVERSITY OF MUMBAI ]

{ for Private circulation only }

General DRAWING 1..... General DRAWING 2 ......BOTTOM........ Home .. .TSEC BREIF.!!!

0] INTRODUCTION

1] LINE WORKS

[*] C.S.L = CIRCUMFERENTIAL SURFACE LINES ...LIKE CONCENTRIC CIRCLES

IN AXIAL VIEW OF A CONE ;CONCENTRIC POLYGONS IN AXIAL VIEW OF A PYRAMID , ALL OF WHICH APPEAR AS STRAIGHT LINES PARALLEL TO THE BASE IN THE NORMAL VIEW OF THE SOLID [WHERE AXIS IS SEEN WITH TRUE LENGTH]

i.e., TO COMBINE ALL THE ABOVE TYPES OF LINES SKILFULLY--FOR EXAMPLE,

--EXISTING EDGES/OUTER LINES OF OBJECT--USE D,T LINE [BY "H" PENCIL]

--AXIS & CENTER LINES --- USE D, Chain , THIN LINE [ BY "2H" PENCIL ]

--REFERENCE LINE [ XY; X1 Y1]; DIMENSIONS/EXTENSION/SECTION LINES--

----------------------------- ----------------------------------------USE D,Tn LINE [BY "2H" PENCIL ]

[2] DIMENSIONS:

USE ALIGNED METHOD OF DIMENSIONS { WITHOUT BREAKS }

{ Unilateral method of Dimensioning is for bigger size drawings }

WITHOUT REPEATING,DISTRIBUTE ALL THE DIMENSIONS AMONG ALL THE DRAWN VIEWS INCLUDING ANY MISSING/AUXILIARY VIEWS.

-------- TRY TO SHOW THE DIMENSIONS IN THE ADEQUATE COMMON SPACE BETWEEN ANY TWO VIEWS, & PREFERABLY NEAR VISIBLE LINES AND NEAR MEANINGFUL/PROFILE VIEWS LIKE STEPS,CIRCLES WHICH WOULD READILY ANSWER THE USERS' NATURAL QUERIES.

PRIMARY DIMENSIONS ARE THE THREE [3] DIMENSIONS X,Y & Z

FV ----- X&Y [ Z=0 ]

TV ----- X&Z [ Y=VERTICAL DIMENSION = 0. i.e., Y IS SEEN AS A POINT ]

SV ----- Y&Z

CATEGORISE ALL THE DIMENSIONS for Easy & Fast checking and Drawing LIKE AS SHOWN BELOW:

i] SHAPE DEFINING DIMENSIONS LIKE (DIAMETER,RADIUS,ANGLE,Etc,.

------------------{LINEAR, CIRCULAR Or ANGULAR DIMENSIONS}

ii]LOCATIONAL DIMENSIONS LIKE HEIGHT , C/C (CENTRE TO CENTRE DISTANCE) , PCD ( PITCH CIRCLE DIAMETER ) ,ANGLE ( DIRECTION ),...

iii]ATLEAST TWO [2] CRITICAL & PRIMARY DIMENSIONS PER EACH VIEW like Y & Z DIMENSIONS IN SIDE VIEW.

[3] INSTRUMENTS :

USE PROFESSIONAL COMPASS, DIVIDERS, SET-SQUARES .

MINI-DRAFTER,T-SQUARE..

KEEP THEM CLEAN & READY TO USE COMFORTABLY & FASTLY.

USE SMALL BOW-COMPASS FOR SMALL CIRCLES.

USE ONLY SET-SQUARES [30,45 & 90 DEGREES] FOR STANDARD ANGLES [DON'T USE PROTRACTOR FOR THESE STANDARD ANGLES].

[4] VISIBILITY IN SOLIDS :

------i} ALL BOUNDARY LINES IN A VIEW MUST BE VISIBLE [D,T]

------ii} THE END/BASE .POINTS TOWARDS THE OBSERVER , IS VISIBLE . THEREFORE THE OTHER END IS HIDDEN ,EXCEPT FOR THE BOUNDARY LINE.

------iii} FACES,EDGES,WHICHEVER ARE DIRECTLY ACCESSIBLE BY THE SIGHT RAYS OF THE OBSERVER , ARE VISIBLE [ OTHERS ARE IN-VISIBLE /DOTTED]

------iv} NO TWO-FULL LINES [ VISIBLE LINES ] CAN INTERSECT,SINCE THEY ARE SEPERATED BY THE OPAQUE SOLID MATERIAL SEPERATING THEM. IF ONE LINE IS VISIBLE ,THEN THE OTHER HAS TO BE HIDDEN.

------v} FROM A HIDDEN CORNER/POINT , SUDDENLY NO VISIBLE LINE EMERGES. VISIBLE CORNER IS JOINED TO ANOTHER VISIBLE POINT BY A VISIBLE LINE.

------vi} ON A DEVELOPMENT OF A SOLID/PLANE SURFACE EVERY THING IS VISIBLE.

THERE IS NOTHING LIKE VISIBILITY {D,T} FOR IMAGINARY LINES LIKE GENERATORS,CSLs,PROJECTORS,Etc,.

BUT ,GENERATORS/CSLs BECOME D,T ONLY WHEN THEY OCCUPY EXTREME TANGENT/OUTER BOUNDARY LINE.

VISIBLE/BOUNDARY GENERATOR LINE NEED NOT BE DARK,THICK [D,T ] IN ANOTHER VIEW, AS IT MAY NOT OCCUPY THE EXTREME/BOUNDARY POSITIONS.

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