Surveyor Notes PDF

TRADE – SURVEYOR (ITI STANDARD) CODE: 387 UNIT I: BASIC ENGINEERING DRAWING Role of Surveyor: Know about the role of a surveyor - State the importance of survey. Layout of drawing sheets and title block: State the m...

TRADE – SURVEYOR (ITI STANDARD) CODE: 387 UNIT I: BASIC ENGINEERING DRAWING Role of Surveyor: Know about the role of a surveyor - State the importance of survey. Layout of drawing sheets and title block: State the measuring of the term ‘Layout’ of drawing sheet - List the different layout styles of drawing sheets - Explain margin, frame, title block etc. Free hand sketching: State the need free hand sketching - List the situations wherein free hand sketching is useful. Drawing equipment - Drawing board, T-Square: State the construction and use of drawing boards and ‘T’ square - State the standard sizes of drawing board as per IS: 1444-1989 - State the standard sizes of ‘T’ square as per IS: 1360-1989 - State the construction and uses of drafting machine - Select the pencil grades for different drawing application - Select the purpose of erasing shield - State the use of set squares in drawing work. Folding of sheets: Explain the method of folding in different size of drawing sheets. Lettering styles: Recognise different lettering styles - Designate the letters and numerals as per IS norms - State standard properties for height, width and spacing of letters. Scales: State the necessity of scales - Explain representative fraction (RF) - List the types of scales - Explain plain, Diagonal scale, comparative scale and Vernier scale. Dimensioning: Explain the types of dimensioning - Explain the elements of dimensioning - Explain the methods of indicating dimensioning - Explain the arrangement of dimensioning. Types of lines and angles: Define points and lines - State classification of lines - State the different types of angles - Explain the method of measuring angles. Triangles and their properties: Define triangles - Name the different types of triangles and state their properties. Quadrilaterals and their properties: Define a quadrilateral - Name the quadrilaterals - State the properties of quadrilaterals. Polygon and their properties: Define a Polygon - Name the Polygon in terms of the number of sides - State the properties of Polygon. UNIT II: CHAIN SURVEYING Introduction about Surveying: Define Surveying - State the object of surveying - State technical terms - State the classification of Surveying - State the principles of Surveying - State the work of Surveyor - State the accuracy in chain Survey - State steel band Measurement of distance by a chain and chaining: State the methods of determining distance - State chaining and chaining a line - State unfolding the chain - Describe the reading the chain - State folding the chain - Calculate the errors in chaining. I & III FLOOR, B&K COMPLEX, SRI RAM NAGAR, KOTTAIYUR, KARAIKUDI-630 106. CONTACT: 94864 31610, 85249 70970, 99521 60010 www.pyramidiasacademy.blogspot.com, [email protected] 1 Introduction about chain survey instruments: State the construction and uses of the following chain survey instruments. Ranging: State ranging - State the necessity of ranging - State the types of ranging - Interpret the signals surveyor and the corresponding action by assistance. Chaining on sloping ground: Explain the methods of changing on sloping ground - State necessity of calculating horizontal distances. Offset and Offsetting: State the meaning of offset and offsetting - State the classification of offsets, its limits and its definition - State the methods of taking offsets for various site conditions. Obstacles in chain surveying: Define obstacles - State the three types of obstacles - Calculate the obstructed distance. Introduction used for setting out right angles: List out the instrument used for setting out right angles - State the types of cross staff and optical square - State the construction of cross staff and optical square - Explain the principles of optical square – State the uses of cross staff and optical square. Introduction about triangulation survey: Define the triangulation and traverse in survey - State closed and open traversed survey - State the three types of survey lines in triangulation Explain about field work. Calculation of area: Calculate the areas of an irregular field - Apply geometrical formula for calculating the area - Describe the construction and use of planimeter. UNIT III: COMPASS SURVEYING Identification and parts of instruments in compass survey: State about traversing - State types of compass - Name the prismatic compass and construction - Construction of surveyor’s compass Determining the bearing of a given triangular plot ABC and calculation of included angles: Calculate angles from bearings - Calculate bearing from angles. Determining the bearing of a given pentagonal plot of ABCDE and calculating included angles magnetic declination and plotting of compass survey: Calculate the angles from bearing for a closed traverse - Calculate the bearing from angles for a closed traverse - Calculate the bearing of a pentagon - Define the dip of the magnetic needles - State the magnetic declination and variations - Calculate true bearing - State local attraction and its elimination - Explain about errors and its limits - State the testing the prismatic compass. UNIT IV: PLANE TABLE SURVEYING Setting up of plane table and methods of plane tabling: State plane tabling - Name the instruments and accessories used in plane tabling - State the construction and uses of instruments accessories of plane tabling - Explain about the setting up of plane table over a station - Explain about leveling, centering and orientation in plane tabling - Explain the methods of plane tabling Methods of plane table survey: Methods of plane table survey - Radiation methods of plane table survey Intersection methods of plane table survey Traversing method of plane table survey: State traverse methods of plane table survey - Conduct traverse methods of plane table survey. Locate and plot new building by two point and three point problem: Define about resection - State I & III FLOOR, B&K COMPLEX, SRI RAM NAGAR, KOTTAIYUR, KARAIKUDI-630 106. CONTACT: 94864 31610, 85249 70970, 99521 60010 www.pyramidiasacademy.blogspot.com, [email protected] 2 two and three point problem - Describe Lehman’s rule - List out the errors in plane tabling - Describe the advantage and disadvantage Prepare a road map for 1/2 km showing details on both sides: Prepare a road map and locate the details on both sides Inking, finishing, colouring and tracing of plane table map: Explain about colouring of surveying symbols - Explain the importance of tracing - State the techniques/order of tracing a drawing - State the different types of reproduction of drawings. Minor instruments used with or without plane tabling: Explain about the construction and uses of Abney level, tangent clinometers, De Lisel’s clinometers. UNIT V: LEVELLING & CONTOURING Instruments Used for Levelling: Explain the tilting level and auto level - Explain the construction a dumpy level - Explain the classification of leveling staff. Introduction of contouring: Define contouring - Explain the terms in contouring - Narrate the characteristics of contour Topography and contour: State Topography - State contour. Tracing of grade contour: Trace the contour gradient for alignment of roads, railways, etc - Determine the volume of earth work and capacity of reservoir Computation of volume: Explain the various methods for the quantity of earth work - Compute quantity of earth work by average depth method - Compute the quantity of earth work by trapezoidal and primordial formula UNIT VI: THEODOLITE Introduction to theodolite: Explain the uses of the theodolite - Explain the classify of the theodolite - Explain the designate of the theodolite Temporary adjustment of theodolite: Set up and perform centering of the instrument - Level up the theodolite - Eliminate parallax Measuring horizontal angle-repetition method: Explain the repetition method - Stage advantage of repetition method - State errors which are not eliminated by repetition method. Measuring vertical angle: Define vertical angle - Differentiate angle of elevation and angle of depression - Explain how to measure vertical angle Deflection angle and direct angle: State deflection angle - Differentiate right deflection angle and left deflection angle - State the direct angle - Differentiate deflection angle and direct angle Prolonging a line: State the method for prolonging a line - Compare the method for prolonging a line - State most suitable method for prolonging a line Intersection of two straight lines: Explain method one : to find intersection point of two lines - Explain method two: to find intersection point of two lines Laying of a horizontal angle: I & III FLOOR, B&K COMPLEX, SRI RAM NAGAR, KOTTAIYUR, KARAIKUDI-630 106. CONTACT: 94864 31610, 85249 70970, 99521 60010 www.pyramidiasacademy.blogspot.com, [email protected] 3 Explain laying of a horizontal angle by ordinary method - Explain laying of a horizontal angle by repetition method - Find equivalent lenier distance for an angular value Traverse: State uses of traverse surveying - State types of traverse - Differentiate open end closed traverse Traverse checking: Explain the checks for open traverse - Explain the checks for closed traverse Classification of traverse: Classify traverse based on the instrument used - Explain method of traversing - Explain how to measure traverse length in theodolite traversing - Explain how to measure traverse angle in theodolite traversing Theodolite traversing method: State methods of theodolite surveying - Explain loose needle method - Explain fast needle method - Compare loose needle and fast needle method Theodolite traversing method II: Explain include angle method - Explain direct angle method - Explain deflection angle method - Explain azimuth method Theodolite phases: Explain theodolite traversing phases Closing error: Define closing error - Find magnitude and direction of closing error Latitudes and departures: Determine latitude - Determine departures - Balance the traverse using transit method - Balance the traverse using Bowditch’s (mathematical) method Balancing the traverse: Explain balancing the error - Describe various mathematical and graphical methods of balancing the traverse Omitted measurements: Describe omitted measurements - List out and explain the classification of omitted measurement Trigonometric leveling (indirect leveling): State advantage of indirect leveling - Explain various cases of trigonometric leveling - deduce the reduce level using the appropriate formula Introduction to curves: Explain the necessity for the provision of curves on road and railway -Explain the classification of curves – Explain the different terms used in curve Setting of horizontal curve by linear method: Determine the elements of curve - Determine the offset from long chord - Explain the method of setting cut curve by offset from long chord Setting out curves by angular methods: Determine the deflection angles of chords - Narrate the procedure of setting out of simple curve by one theodolite and tape method UNIT VII: TACHOMETRY Methods of tachometry: List the methods of tachometry - Explain the fixed hair method - Explain the movable hair method Tangential method of tachometry: Explain the tangential method of tachometry - Explain the construction of substance bar - Explain the substance method of tachometry Triangulation: Explain the term triangulation I & III FLOOR, B&K COMPLEX, SRI RAM NAGAR, KOTTAIYUR, KARAIKUDI-630 106. CONTACT: 94864 31610, 85249 70970, 99521 60010 www.pyramidiasacademy.blogspot.com, [email protected] 4 UNIT VIII: MODERN SURVEYING INSTRUMENTS Digital theodolite: Explain the features of the digital theodolite - Explain the difference between theodolite and digital theodolite Total Station: Describe the features of the total station - Explain evolution of total station from the conventional equipment - Narrate the benefits of total station Remote sensing: Explain remote sensing and photogrammetry. GPS: Explain the features of global positioning system(GPS) - Narrate the use of GPS and method of surveying for accurate output - List the benefits of GPS UNIT IX: CADD Introduction to cad: Explain the term CAD - Explain the use of CAD Draw tool bar: Explain draw commands in CAD - Explain the method of drawing geometrical shapes in CAD Layers: Explain the dimensioning method in CAD - Explain the use of object snap in CAD Modifying tool bar: List out various modifying tools in CAD - Explain the uses of modifying tools in CAD Printing cad drawings: Explain the steps involved in plotting in cad UNIT X: BUILDING & DRAINAGE Building Drawing: State the requirement of a good building drawing - State the method of drawing plan, elevation and typical section - State the scales used in building drawing - State Dimensioning and printing for building drawing. Drainage: State drainage and surface drainage - State four shapes of surface drainage. I & III FLOOR, B&K COMPLEX, SRI RAM NAGAR, KOTTAIYUR, KARAIKUDI-630 106. CONTACT: 94864 31610, 85249 70970, 99521 60010 www.pyramidiasacademy.blogspot.com, [email protected] 5  1 Construction Surveyor : Safety Exercise :1.1.01 Importance of surveyor Objectives : At the end of this exercise you shall be able to know about the role of a surveyor state the importance of survey. Now a days for the purpose of designing any engineering Therefore a through knowledge of the theory of project such as road, railway, canal water - supply a surveying and still in practice, good judgement and sanitary schemes etc. Surveyor would require to study organisation are the essential requisites of a good the very first item the features of the earth’s surface in surveyor which can be acquired by taking more interest which the project is to be located. in the field work. Then he should prepare a map of the area. Importance of survey The success of any engineering project is based upon The planning and designing of all civil engineering the accurate and complete survey work. projects such as construction of bridges, tunnels route location and exploration for highways,air fields, Therefore surveyor must thoroughly familiar with the railways, power lines and pipe lines are based upon principles and practice of surveying. the surveying measurements. The role of a surveyor can be divided into three parts. Moreover during execution project of any magnitude 1 Field work is constructed along the lines and points established by surveying. Thus surveying is a basic requirement 2 Office work for all civil engineering projects. The other principal 3 Care and adjustments of instruments. works in which surveying is primarily utilised are: 1 Field work To fix the national and state boundaries. Taking measurements for details To chart coast lines, navigable streams and lakes. Recording the field notes To establish control points. Setting out of works. To execute hydrographic and oceanographic charting 2 Office work and mapping. Preparing maps, plans and sections from the data To prepare topographic map of land surface of the collected in the field. earth. Calculating the areas and volumes. To determine the latitudes longitude and azimuth from astronomical observation. Designing of various structures. To carryout surveying specific for open cost and 3 Care and adjustments of instruments underground mixing purposes The surveyor must be thoroughly familiar with the Maping as various scales and essential for the instruments which he will be used (handing) economic development of natural resources, industrialized areas and for administration, national He must know the methods of testing and adjusting development and defence. Therefore, Aerial the instruments. photographs are used for surveying work to attain the Very costly instruments such as theodolite, Auto levels required degree of accuracy and at a minimum cost etc. must be handled with great care and accuracy. and in a minimum time. Before taking of instruments such as level/theodolite from the box, the correct position of various parts should noted and a rough sketch to be made for replacing of instruments after finishing survey works. The lenses of the instruments should be protected from the sun, dust and rain. Movable parts should be cleaned and lubricated with refined oil at frequent interval. 1  2 Construction Related Theory For Exercise: 1.2.07 Surveyor - Basic Engneering drawing Drawing Instruments, Equipments and materials Objectives: At the end of this lesson you shall be able to state instruments, equipments and materials list out instrument, equipments and materials state the standard as per 962-1987 to use different drawing instruments, equipments and materials follow Precautions in the use of instruments, equipments and materials. Introduction Engineering Drawing is the language of engineers, the accuracy and neatness of the engineering Drawing depends on the quality of the instruments, equipments and material used. Hence, preference should be given to standard instruments and equipments and surveyor should be able to use different drawing instruments. List of instruments Drawing board Tee-square or Mini Drafter Drawing Boards Drawing sheets Sl. Set-square No. Sizes in mm to be used with Designation designation (LxWxT) Scale 1 BO 1500 x 1000 x 25 AO Protractor 2 B1 1000 x 700 x 25 A1 French curves 3 B2 700 x 500 x 15 A2 Stencil 4 B3 500 x 350 x 15 A3 Drawing instruments box List of equipments The following precaution may be taken in handling the drawing boards: Drafting machine Always keep an extra sheet on the top surface of the Computer for Auto CAD. (Monitor UPS, CPU, key drawing board. board, mouse, etc.) Do not keep anything on the top flat surface of the Plotter/Printer drawing board. List of materials Take sufficient care in up keeping the straightness Drawing papers of the ebony edge. Drawing pencils Drawing papers: (Fig 2) Rubber/ Eraser Drawing papers fasteners (Drawing pins, Cello tape) Tracing paper or tracing film Drawing board (Fig 1) The standard size should be as per IS: 1444-1963/1977 of Bureau of Indian Standards. The standard size as per Bureau of Indian standard (B.I.S) 30  1 When not in use, T-square should be left flat on the 3 Designation Trimmed size Untrimmed size (mm) (mm) drawing board or suspended from the hole at the end of the blade. A0 841 x 1189 880 x 1230 2 Clean the blade with moist cloth to remove lead A1 594 x 841 625 x 880 particles. A2 420 x 594 450 x 625 3 Do not use T-square as a hammer to drive in the A3 297 x 420 330 x 450 drawing pins etc. A4 210 x 297 240 x 330 4 Do not use the ebony edge as a straight edge for cutting paper with knife. A5 148 x 210 165 x 240 5 Ensure that the screw heads are tight. 1 The size of the drawing sheets to be used depends T-square is used to draw only horizontal lines. on the size of the object to be drawn and the scale to Do not use lower edge of the T-square to draw be used. horizontal lines. While drawing horizontal 2 The length of the drawing sheet can be horizontal or lines, the pencil should be slightly inclined vertical while drawing. towards the right. Vertical and inclined lines are drawn with the help of set squares. 3 A2 size of drawing sheet is most convenient for drawing purposes in the class room. Mini drafter(Fig 5) 4 The width to length ratio of drawing sheet is1: 2 5 Area of A0 drawing sheet is 1.00 square metre. T-square (Fig 3) It consists of two parts, a long strip called blade and a short strip called head or stock. The blade is fitted with an ebony or plastic piece on its upper edge to form a It is a simple and small shaped instrument of the drafting working edge. machine. Now-a-days these are mostly used by the The following precautions may be taken in handling engineering students. All the working functions of T- the T-square: (Fig 4) Square, Set-Square, Protractor, Scales and their merits are co-ordinated in a Mini-Drafter. Set-square (Fig 6 and Fig 7) It is made of transparent celluloid plastic in triangular shape They are available in two types, 300-600 and 450- 450. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.07 31  4 Protractor: (Fig 8) It is made of transparent celluloid plastic, available in semi circle or circle. Compass (Fig 9) It is used for drawing circles both in pencil and in ink. It consists of two legs hinged at one end. One leg is attached with a steel needle by means of a screw while the other leg is provided with a socket to accommodate interchangeable attachments. Dividers (Fig 10) Engineer’s scales (Table) It is used to make full size, reduced size or enlarged size drawings conveniently, depending upon the size of the object and that of the drawing sheet. They are made of cardboard, plastic and as recommended by Bureau of Indian Standards, are available in set of eight scales. They are designated from M1 to M8. Table Designation Description Scales M1 Full size 1:1 50 cm to a metre 1:2 M2 40 cm to a metre 1:2.5 20 cm to a metre 1:5 M3 10 cm to a metre 1:10 Dividers are similar to the compass and are made in square, flat and round forms. They are used for: 05 cm to a metre 1:20 1 Dividing curved or straight lines into any number of M4 02 cm to a metre 1:50 equal parts. 01 cm to a metre 1:100 2 Transferring dimensions from one part of the drawing M5 5 mm to a metre 1:200 to another part. 2 mm to a metre 1:500 3 Setting dimensions form the scale to the drawings. M6 3.3 mm to a metre 1:300 Drawing pencils (Fig 11) 1.66 mm to a metre 1:600 M7 2.5 mm to a metre 1:400 1.25 mm to a metre 1:800 M8 1 mm to a metre 1:1000 1.5 mm to a metre 1:2000 These are in many grades. The grade HB denotes medium soft. The grade H denotes the degree of hardness in an increasing order. Similarly, grade B indicates the degree of softness in an increasing order. The lead of the wood pencil may be sharpened in the following ways 1 Cylindrical 2 Conical 3 Wedge (Chisel edge) 4 Bevel Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.07 32  5 Mechanical clutch pencil is very common in use. This is Eraser very simple, easy to use, requires no sharpening time Soft pencil erasers are ideal for erasing pencil marks. and even cheaper in long run. Hence, this type of pencil This eraser will not destroy the surface of the paper and is preferred by professional surveyor. Students using hence drawing can be re-penciled. these types of pencils will save a lot of time. Fastener: (Fig 12) 1 Only a sharp pencil can make quality drawing and hence, sharpen the pencil as and when it is necessary. Following materials are used to fix the drawing sheet on the drawing board. 2 Sharpen the pencil only where there is no grade mark. - Thumb pins 3 In a compass H pencil sharpened to bevel point, having its wedge shaped side slopping outside, is - Cello tapes used. - Fold back gap spring clips. 4 As a general guide, use: Template I HB pencil for sketching Templates are available for drawing circles, arcs, ellipses, II H for outlines, visible lines, finishing, dimensioning, triangles, squares and other polygons. Also, symbols lettering, arrows etc. used by various engineering faculties, such as architectural, mechanical, electrical, chemical etc. are III 2H for construction lines, dimension lines, centre lines, now available in the form of templates. section lines etc. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.07 33  Selection 6 HB- For free hand works H- For making drawing and lettering 2H- for drawing construction lines, dimensions lines, section lines and centre lines. 3H, 4H- For drawing minute details B- For shading Precautions in the use of instruments: Following precautions should be taken while doing the drawing works, 1 The lower edge opposite to the working edge of the Tee-Square should not be used for drawing horizontal lines. 2 T- Square should not be used as hammer to drive to drawing board pins. 3 Measuring scales should not be used as hammer to drive to drawing pins. 4 Drawing sheets should never be cut by blade or knife with the T-Square blade as the guide. Stencils Stencil is a thin flat piece of celluloid used to write letters 5 All the instruments and drawing sheet etc. Should be and numerals. This helps the draftsmen to write neatly thoroughly dusted off and cleaned before starting the and uniformly and at a faster rate. work. French curves (fig.13) 6 No end of the pencil should be kept in mouth. A French curve is a curved ruler used for drawing irregular curves that are neither circles nor circular arcs. It is made 7 No oiling should be done to the joints of the of wood, plastic or transparent celluloid. There are instruments; otherwise, oil will give stains or spots on different forms and sizes of French curves. the drawing sheets. 8 Only required instruments should be kept on the drawing board. All extra instruments should be kept away in drawer. 9 Divider should not be used as pincer. 10 Soaking paper should not be used for drying the ink. 11 After completing the work all the instruments should be properly cleaned. Conclusions Flexible curve One should practice handling and using drawing instruments before attempting complex drawing Flexible curve is made out of materials having flexibility. problems. Developing correct drawing habits will enable It is made of lead bar enclosed in rubber and can be bent to make continuous improvement in the quality of into any shape to form a curve. It helps to draw smooth drawings. Each drawing will offer an opportunity for curve passing through any given points. Flexible curves practice. Later on, good form in the use of instruments of various sizes are now available in the market. will become a natural habit. 34 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.07  7 Construction RelatedTheory For Exercise 1.2.08 Surveyor - Basic Engineering drawing Fixing of drawing sheet on drawing board Objectives: At the end of this lesson you shall be able to Explain the method of fixing of drawing sheet in board Task 1. Fixing the drawing sheet on drawing board Place the drawing paper centrally on the drawing board. Butt the Tee square head with the working edge of the drawing board and align the top edge of the drawing sheet. Hold the drawing sheet by hand in the same position and fix the sheet in this position with drawing pin/ cellulose tape.(Fig 1) Set off the margin distance using scale. Draw four border lines as shown. mark and draw the title block. 35  8 Construction Related Theory For Exercise: 1.2.09 Surveyor - Basic Engineering Drawing Layout of drawing sheet and title block Objectives: At the end of this lesson you shall be able to state the system of Layout of drawing sheet list the different layout for designated drawing sheet explain the Title block. Lay out : Layout is standard arrangement of placing drawing should be drawn within the layout boundary. The margin, title block etc for a particular size of drawing layout lines are called borders. ‘borders’ are enclosed by paper. It was explained earlier that the size of drawing the margins from edges of the trimmed size of sheet. sheets and standardised and designated as A0, A1, It is recommended that within the borders on the left side A2,A3,A4 &A5.Different layout styles for drawing papers have minimum width 20mm for the sheet sizes A0, A1 and from A0 to A5 sizes as per IS : 10711 - 1983. (Figs 1 &2) 10mm for the sheet sizes A2, A3,A4& A5 for the space for Margin : Margin enable the prints to be trimmed After filing. (Refer Figs 1& 2) fixing the drawing paper over the drawing board,before commencing the drawing , the layout is to be drawn. The 36  9 the sheet be taken horizontal or vertical depending upon Frame : The frame limitting the drawing space should be the nature of the drawing as sheet type ‘X’ and sheet type executed with continouus thin line of 0.5mm. ‘Y’. (Fig 3 & 4) Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.09 37  of arrow heads and should be placed across the frame 10 one at shorter side and one at longer side coinciding with the centering marks. One of the orientation marks always points towards the draughtsman. Metric reference graduation (Fig 8): It is shown only on drawings without (metric) dimensions. It shall have mini- mum 100 mm long divided into 10 equal intervals max. width 5 mm. It should be executed with thin continuous line (0.5 mm) disposed symmetrically about a centering mark. Grid reference (Fig 9): In order to facilitate easy location Title block (Fig 5): This is the block in which the particu- of features on large drawings (assembly) grid reference lars of the organisation. Name of the drawign and other system is recommended. It is similar to lines of latitude particulars are printed. It is situated in the bottom right and longitude on a map. The number of divisions shall be hand corner of the drawing sheet. Figs 1 & 2 shows the divisible by two. The length of any side of the rectangle of position of the title block. Contents of the title block and the grid shall not be less than 25 mm and not more than their relative position vary to suit individual concern. 75 mm along the frame. These are the special require- ments for production of assembly drawings. Centering marks (Fig 6): When the drawings on the drawing sheet are to be microfilmed (preserving by taking negatives) centering marks to be provided. Trimming marks (Fig 10): These marks are required for the sheets which require trimming. Example printed These marks shall be placed at the ends of the two axis copies of drawings. In such cases the trimming marks are of symmetry of trimmed sheet. It is executed with 0.5 mm drawn on the drawing tracing sheet. minimum thick stroke, starting from the edges of the trimmed sheet. It shall extend approximately 5 mm beyond drawing frame. Orientation marks (Fig 7): Orientation marks are used in order to indicate the orientation of the drawing (arrow head) sheet on the drawing board. These marks consist 38 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.09  11 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.09 39  12 Folding of sheets Objectives: At the end of this lesson you shall be able to explain the method of folding in different size of drawing sheets. The purpose of folding the drawing sheet for storing to the correspondence files. For binding in special reports is illustrated in the file. All the maps and plans are folded to final size for conven- ience of record in office files. Method of fold the different sizes of drawing sheets. Lower portion of the left-hand margin of the sheet may be cut after retaining 297mm long top portion in order to provide for filing the drawing in the files. Plans may be opened out easily by holding firmly the top left-hand corner and pulling the bottom right-hand corner. The following procedure shall be adopted inorder a) Always fold vertically first. b) Fold horizontally next. c) Folded drawing to be of A4 size. d) Title block to be on the topmost fold for easy refer- ence. A0-size Fold the A0-size sheet. Folding vertically, from left side to right side. 1st fold 210mm 2nd & 3rd - fold each 109.5mm Other 4th to 6th folding are 190mm each. 5th folding 297mm.(Fig 3) Fold horizontally 7th folding from the top to bottom 247mm. 8th folding is from the 7th folding point 297mm. Title block will always come top of the right side corner. 9th folding is top left side rectangular portion folded diagonally. (Fig 1) After completion of folded the drawing sheet. (Fig 2) Fold the A1 Size sheet: (594 x 841) Folding vertically, from left side to right side. 1st fold 210mm 2nd & 3rd - fold each 125.5mm Other 4th 190mm Folding horizontally from top 6th folding is top left side rectangular portion folded diagonally as shown in figure. After completion of folded the drawing sheet. (Fig 4) Fold the A2 Size sheet: (420 x 594) Folding vertical, from left side to right side. 1st folding 210mm. 2nd folding 190mm from the right side. 40 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.09  13 Folding horizontally from bottom 3rd folding 297mm. (Fig 5) 1st folding 210mm. 2nd folding 190mm from the right side of the drawing sheet. (Fig. 9 & 10) The method of folding the drawing sheet, the title 4th folding is top left side rectangular portion folded block should appear at the right bottom of the diagonally as shown in figure. folded sheet finally. After completion of folded the drawing sheet. (Fig. 6) Fold the A2 Size sheet: (594 x 420) Folding vertically from left side to right side. 1st folding 210mm 2nd flolding 192mm from the right side of the drawing sheet. Folding horizontally from the bottom, 3rd folding 297mm. 4th folding is top left side rectangular portion folded diagonally as shown in (Fig. 7) After completion of folded the drawing sheet. (Fig. 8) Fold the A3 size sheet: (297 x 420) Folding vertically from left side. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.09 41  14 Construction RelatedTheory For Exercise: 1.2.10 Surveyor-Basic Engineering Drawing Lettering styles Objectives: At the end of this lesson you shall be able to recognise different lettering styles designate the letters and numerals as per IS norms state standard proportion for height, width and spacing of letters. Apart from graphical elements (lines, arcs, circles etc) Lower case letters and numerals technical drawings will also contain written informations. These written informations are referred as “lettering”. Width Letters/Numerals Width (W) Styles of lettering: Many styles of lettering are in use to 1 i 1d day. However, a few styles which are commonly used are 3 j,l 3d shown in Fig 1. 4 f,t,l 4d 5 c,r 5d 6 a,b,d,e,g,h,k,n,o,p,q,s,u,v;3;5 6d 7 a,0 (zero), 2,4,6,7,0,8,9 7d 9 m 9d 10 w 10d The width of different letters in terms of stroke (line) is as follows: Lettering B. IS:9609 Width (W) Capital letters 1 I 4 J Standard heights/Width: The standard heights recom- 5 C,E,F,L mended by BIS (IS:9609-1983) are in the progressive ratio of “square root 2”. They are namely 2.5 - 3.5 - 5 - 7 6 B,D,G,H,K,N,O,P,R,S,T,U & Z - 10 - 14 and 20 mm. The height of lower case letter 7 A,M,Q,V,X,Y (without tail or stem) are 2.5, 3.5, 5, 7, 7, 10 and 14 mm. 9 W There are two standard ratios for the line thickness “d”. They are A & B. In A = line thickness (d) is h/14 and in B Lower case letters and numerals = line thickness (d) is h/10. Width (W) Letters/Numerals The width of different letters in terms of “d” is as follows: 1 i Lettering A 2 l Width Capital letters Width 3 j:l (W) 4 c,f,r,t 1 I 1d 5 a,b,d,e,g,h,k,n,o,,q,s,u,v,x,y,x 5 J,L 5d 0,2,3,5 to 9 6 C,E,F 6d 0,2,3,5 to 9 7 B,D,G,H,K,N,O,P,R,S,T,U & Z 7d 6 a,4 8 A,Q,V,X,Y 8d Fig 2 & 3 shows the sequence of printing single stroke 9 M 9d capitals and lower capital letters in vertical style. 12 W 12d 42  15 Inclined letters (Fig 3) are drawn at an angle of 15° Spacing of letters: Recommended spacing between towards right side, the proportion being the same as of character, minimum spacing of base lines and minimum vertical lettering. spacing between words as per Indian Standards (IS:9609- 1983) is given below in figure No.4 and Table 1 & 2. Fig 3 shows single stroke/lower case letters also. Standard letters to suit the nature of instructions, the sizes should be selected. All the lettering should be printed, so that they are read/viewed from the bottom of the drawing. Lettering makes or mars the appearance and legibility of the drawing. Always maintain uniform lettering (letters and numerals) which can be reproduced within reason- able time with ease. In machine drawing ornamental lettering should never be used. TABLE 1 Lettering A (d = h/14) Values in millimetres Characteristic Ratio Dimensions Lettering height h (14/14)h 2.5 3.5 5 7 10 14 20 Height of capitals Height of lower- c (10/14)h - 2.5 3.5 5 7 10 14 case letters (without stem or tail) Spacing between a (2/14)h 0.36 0.5 0.7 1 1.4 2 2.8 characters Minimum spacing b (20/14)h 3.5 5 7 10 14 20 28 of base lines Minimum spacing c (6/14)h 1.06 1.5 2.1 3 4.2 6 8.4 between words Thickness of d (1/14)h 0.18 0.25 0.35 0.5 0.7 1 1.4 The spacing a between two characters may be reduced by half if this gives a better visual effect, as for example LA, TV; it then equals the line thickness d. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.10 43  TABLE 2 16 Lettering B (d = h/10) Values in millimetres Characteristic Ratio Dimensions Lettering height h (10/10)h 2.5 3.5 5 7 10 14 20 Height of capitals Height of lower- c (7/10)h - 2.5 3.5 5 7 10 14 case letters (Without stem or tail) Spacing between a (2/10)h 0.5 0.7 1 1.4 2 2.8 4 characters Minimum spacing b (14/10)h 3.5 5 7 10 14 20 28 of base lines Minimum spacing c (6/10)h 1.5 2.1 3 4.2 6 8.4 12 between words Thickness of d (1/10)h 0.25 0.35 0.5 0.7 1 1.4 2 lines The spacing between two characters may be reduced by half if this gives a better visual effect, as for example LA, TV: it then equals the line thickness d. Types of Lines Objectives: At the end of this lesson you shall be able to define points and lines state the classification of lines state the different types of angles explain the method of measuring angles. A point represents a location in space, having no width or height. It is represented by drawing intersection of lines or a dot. (Fig 1) Line is the path of a point when it moves. It has no thickness and are of two types: – Straight line – Curved line Straight line : It is the path of a point when it is moving in a particular direction. It has only length and no width. (Fig 2) Also a straight line is the shortest distance between two points. Straight line, depending on its orienation are horizontal lines are called vertical lines. It can be treated classified as Horizontal, vertical and Inclined or Oblique as a line along the plumb line of the plumb bob or parallel line. to a plumb line. (Fig 4b) Horizontal line (Fig 2) : Horizontal lines are those which Inclined line or Oblique line : A straight line which is are parallel to a horizontal plane. Example of horizontal neither horizontal nor vertical is called an inclined line. plane is the surface of a still water. (Fig 3) (Fig 5) Vertiacl line (Fig 4a ) : Lines which are perpendicular to 44 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.10  17 Parallel lines : They are the lines with same distance between them. They may be straight lines or curved lines. Parallel lines do not meet when extended. (Fig 7) Perpendicular lines : When two lines meet at 90°, the two lines are said to be perpendicular to each other. One of this line is called as reference line. (Fig 8) Curved line : It is the path of a point which always changes its direction. Examples of curved lines are shown in(Fig 6) Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.10 45  18 Construction RelatedTheory For Exersice: 1.2.11 Surveyor - Basic Engineering Drawing Method of Dimensioning Objectives: At the end of this lesson you shall be able to explain the types of dimensioning explain the elements of dimensions explain the methods of indicating dimensions explain the arrangement of dimensioning Importance of dimensioning: Any Component or product manufactured should be confirm to its specification. In fact, without specification of product, there cannot be production. In engineering industry, all manufacturing is controlled by the technical specification of product or components. Technical specification provides complete information on the shape, size, tolerance, finish, material and other technical aspects such as heat treatment, surface coating and other relevant information required to manufacture a component. In most cases technical specifications of components is given in the form of a technical drawing while shape is described by various types of views i.e Orthographic, pictorial and perspective projection and When construction line are required to be shown for size is given by dimensions. practical purposes of the intersecting projection lines extend beyond their point of intersection. (Fig 3) Definitions related to dimensioning Dimension: It is a numerical value expressed appropri- ate unit of measurement and indicated graphically on technical drawings with lines, symbols and notes. Elements of dimensioning – Extension line - a – Dimension line - b Extension lines (Projection lines) should not cross the – Leader line - c dimension lines, but where not possible the lines should – Termination of dimension line not break. (Fig 4) – The original (starting point) indication and the dimen- sion (a). Extension line: It is a thin line projecting from the feature and extending beyond the dimension line. (Fig 1) Dimension line: These are thin continuous lines, termi- nated at ends by arrow heads, dots or oblique lines touching the extension line. (Fig 5) Dimension line may cut or cross another dimension line where there is no other way. Dimension to the hidden lines be avoided. (Fig 6) It is normally perpendicular to the feature being dimen- sioned, but may be drawn obliquely as shown for Arrow heads may be placed outside where space is dimensioning tapers, parallel to each other. (Fig 2) insufficient. 46  19 right-hand side of the drawing. Dimension lines are not broken. Dimensioning of angles also given in the same way. (Figs. 7 & 8) This method is known as aligned system of dimensioning. Method 2 Leader line: It is a thin continuous line. It connects a note or dimension with the features to which it applies. (Fig 6) Dimensional values shall be indicated so that they can be read from the bottom of the drawing sheet. Non-horizon- Termination and Origin indication: The size of the tal dimension lines are interrupted, preferably near the terminations (arrow heads/oblique strokes) shall be pro- middle so that the value can be inserted. (Fig 9 & 10). This portional to the size of the drawing. Only one style of arrow method is termed as unidirectional system of head shall be used on a single drawing. However, where dimensioning. the space is too small for the arrow heads, it may be substituted by a dot or by an oblique line. Arrow heads are drawn as short lines forming barbs at any convenient included angle between 15° and 90°. They may be open, closed or closed and filled in. Oblique strokes drawn as short line inclined at 45°. (Fig 5) Indicating dimensional values on drawings: All di- mensional values shall be shown on drawings in charac- ters of sufficient size to ensure complete legibility on the original drawings as well as on reproductions made from micro-filming. They shall be placed in such a way that they are not crossed or separated by any other line on the drawing. Methods of indicating values: There are two methods used for indicating the values. Only one method should be used on any one drawing. Method 1 Dimensional values shall be placed parallel to their di- mension lines and preferably near the middle, above and clear of the dimension line. However, values shall be indicated so that they can be read from bottom or from the Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.11 47 Arrangement and indication of dimensions Dimensioning smaller width: Arrow heads are replaced 20 by oblique lines. (Fig 13) The arrangement of dimensioning on a drawing shall indicate clearly the design purpose. The arrangements of dimensioning are: – Chain dimensioning – Dimensioning from a common feature – Dimensioning by co-ordinates – Combined dimensioning. Chain dimensioning: It is used where the possible accumulation of tolerances does not infringe (effect) on the functional requirement of the component. (Fig 11) To avoid placing dimensions too far away from feature, dimension lines are drawn closer and not fully. (Fig 14) Dimensioning from a common feature is used where a number of dimensions of the same direction relate to a common origin. Dimensioning from a common feature may be executed as parallel dimensioning or as superimposed running dimensioning. Parallel dimensioning: Dimensions of features are taken from one datum/common origin and are shown parallel to other and placed, so that the dimensional values can easily be added in Fig 12. 48 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.11  21 Construction RelatedTheory For Exercise : 1.2.12 Surveyor - Basic Engineering Drawing Construction of plain Geometrical figures Objectives: At the end of this lesson you shall be able to state the different types of angle state the method of measuring angle. Angles : Angle is the inclination between two straight Stright angle : This refers to angle of 180°. This also lines meeting at a point or meet when extended. AB and called as the angle of a straight line. (Fig 5) BC are two straight lines meeting at B. The inclination between them is called an angle. The angle is expressed in degrees or radians. Concept of degree : When the circumference of a circle is divided into 360 equal parts and radial lines are drawn through these points, the inclination between the two adjacent radial lines is defined as one degree. Thus a Reflex angle : It is the angle which is more than 180° circle is said to contain 360°.(Fig 1) (Fig 6) Acute angle : IF an angle which is less than 90° is called an acute angle. (Fig 2) Right angle : Angle between a reference line and a perpendicular line is called right angle. (Fig 3) Adjacent angles : These are the angles lying on side of a line. (Fig 7) Complementary angles : When the sum of the two angles is equal to 90°, angle POQ + angle QOP+ angle POQ and angle QOR are complementary angles to each other.(Fig 8) Obtuse angle : This refer to an angle between 90° and 180°. (Fig 4) Supplementary angle : When the sum of the two adjacent angles is equal to 180°,example angle SOT + angle TOY = 180°,angle SOT and angle TOY are supplementary angles to each other. (Fig 9) 49 Protractor : Protractor is an instrument for measuring 22 angles. It is semi - circular or circular in shapes and is made of flat celluloid sheet. The details of graduation in a semi- ciccular protractor is shown in figure 10. The angles can be set or measured from both sides,aligning the reference line and point ‘0’ with the corner point of the angle. Figure 10 shows how to read or set the angle protractor can also be used to divide a circle or drawing sectors. Triangles and their types Objectives: At the end of this lesson you shall be able to define triangles name the different types of triangles and state their properties. Trlangle is a closed plane figure having three sides and – Scalene triangle has all the three sides unequal in three angles. The sum of the three angles always equals lengths. All the three angles are also unequal. (Fig 3) to 180°. To define a triangle, we need to have a minimum of three measurements as follows. – 3 sides or – 2 sides and one angle or – 2 angles and one side – Right angled triangle is one in which one of the Types of triangles angles is equal to 90° (Right angle). The side opposite – Equilateral triangle is a triangle having all the three to right angle is called hypotenuse. (Fig 4) sides equal. Also all the three angles are equal (60°) (Fig 1) – Isosceles triangle has two of its sides equal. The – Acute angled triangle is one in which all the three angles opposite to the two equal sides are also angles are less than 90°. (Fig 5) equal.(Fig 2) – Obtuse angled triangle has one of the angles more than 90°. (Fig 6) 50 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12  23 The sum of the three angles in any triangle is equal to 180°. The sum of any two sides is more than the third side. Quadrilaterals and their properties Objectives: At the end of this lesson you shall be able to define a quadrilateral name the quadrilaterals state the properties of quadrilater. Quadrilateral is a plane figure bounded by four side and Rectangle (Fig 2) : In a rectangle, opposite sidea are four angles. Sum of the four angles in a quadrilateral is of equal and parallel and all four angles are right angles. interior angles is equal to 360°. The side joining opposite To construct a rectangle we need to know the length (a) corners is called diagonal. To construct a quadrilateral of two adjacent sides or (b) diagonal and one side. four sides, four angles and two diagonals minimum of five dimensions are required of which two must be sides. Fig 2 shows a rectangle ABCD. Sides AB = DC and BC Quadrilaterals are also referred as Trapezoid. = AD. Diagonals AC and BD are equal, bisect but not at right angles. Types of quadrilaterals. (Fig 1) Rhombus (Fig 3) : In rhombus all the four sides are equal, but only the opposite angles are equal. ABCD is the rhombus where AB = BC = CD =AD. – Square – Rectangle – Rhombus – Rhomboid/ Parallelogram – Trapezoid – Trapezium Square : In a square all the four sides are equal and its four angles are right angles. The two diagonals are equal Angle ABC = Angle ADC and BAD = Angle BCD. and perpendicular to each other. Diagonals AC and BD are not equal but bisecting at right To construct square we need to know (a) length of the side angles. or (b) length of the diagonal. AO = OC and BO = OD. To construct a rhombus we need to know (a) two diagonals (b) one diagonal and an opposite angle or (c) one side and its adjacent angle. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12 51  24 Rhomboid/ Parallelogram (Fig 4) : In a parallelogram opposite sides are equal and parallel. Opposite angles are also equal. Diagonals are not equal but bisect each other. ABCD is a traperzoid, sides AB and DC are paralel but not equal. Diagonals AC and BD and AO = OC need not be equal. Sides AD and BC may some times equal. Parallelogram is also known as rhomboid. To construct a parallelogram we need (a) two adjacent sides and angle Trapezium (Fig 6) : It is a plane figure of 4 sides, and any between them or (b) one side, diagonal, and angle between two sides equals to each other. them or (c) two adjacent sides and perpendicular distance between the opposite sides. In the parallelogram ABCD, AB =DC; AD = BC Angle DAB = angle DCB, angle ABC =angle ADC Sides AB,CD and AD, BC are parallel. Diagonals AC and BD are not equal but bisect at 0. Trapezoid (Fig 5) : It is a quadrilateral, all the four sides are different and only two sides are parallel, all the four angles are different. The diagonals do not bisect at right angles. Polygon and their properties Objectives: At the end of this lesson you shall be able to define a polygon name the polygon in terms of the number of sides state the properties of polygon. Polygon is plane fgure bounded by many (usually five or more ) straight lines. When all the sides are included angles are equal, it is called as a regular polygon. Names of polygons : Polygons are named in terms of their number of sides are given below : (Fig 2) Name No. of sides Pentagon Five sides Hexagon Six sides Heptagon Seven sides Octagon Eight sides Nonagon Nine sides Decagon Ten sides Undecagon Eleven sides Dodecagon Twelve sides 52 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12 Properties of polygon 25 The sum of the interior angles of a polygon is equal to All corners of a regular polygon lie on the circle. The (2xn-4) x rt angle, where n is the number of sides. sides of a regualar polygon will be tangential to circle The sum of exterior angles of a polygon is equal to drawn in side. (Fig 3) 360°. The sum of the interior angle and the corresponding external angle is 180°. (Fig 4) Circles Objectives: At the end of this lesson you shall be able to state what is a circle name its elements state the function of a compass explain concentric and eccentric circles. Circle : Circle is a plane figure bound by a curve, formed by the locus of a point which moves so that it is always at a fixed distance from a stationery point the “Centre”. Radius : The distance from the centre to any point on the circle is called the “Radius”. Diameter : The length of a straight line between two points on the curve, passing through the centre is called the “Diameter”, D : Dia or d. It is twice the radius. Circumference : It is the linear length of the entire curve, equal to π D Arc : A part of the circle between any two points on the circumference or periphery is called an ‘Arc’. Chord : A straight line joining the ends of an arc is called the chord. (Longest chord of the circle is the diameter) Segment : A part of the circle or area bound by the arc and chord is the segment of the circle. Sector : It is the part of a circle bounded by two radii (plural of radius) meeting at an angle and an arc. Quadrant : Part of a circle with radii making 90° with each other is a quadrant (one fourth of the circle). Eccentric circles : Circles within a circle but with different Half of the circle is a straight line just touching the circle centres are called eccentric circles. (Fig 3) at a point. It does not cut or pass through the circle when extended. The point of tangent touches the circle is called the “ point of tangency”. The angle between the line joining the centre to the point of tangency and the tangent is always 90°. Fig 1 shows all the above elements. Concentric circles : When two or more circles (drawn) having common centre, they are called concentric circles. Ball bearing is the best example of concentic circles. (Fig 2) Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12 53  26 Introduction about surveying Objectives: At the end of this lesson you shall be able to define surveying state the object of surveying state technical terms state the classification of surveying state the principles of surveying state the work of surveyor state the accuracy in chain survey state steel band. Surveying Technical Terms The art of determining the relative positions of the objects The following technical terms are generally used in sur- on the surface of the earth by taking measurements in veying both horizontal and vertical plane. Plan : A plan is the graphical representation of the Object of surveying features on the earth surface or below the earth surface as projected on a horizontal plane. On a plan horizontal To obtain a map or a plan of the area to be surveyed. distances and directions are generally shown. Divisions: Map: The representation of the earth surface on a small The two main divisions of surveying are scale is called a map. The map must show its geographi- cal position of the earth. 1 Plane surveying Topographical map: The maps drawn in a large scale to 2 Geodetic surveying identify the individual features and positions of various objects on the earth surface is called Topographical map. The shape of the earth is elliptical in nature, but assumed to be a spheroid. The line joining of any two points on the Triangulation: The area to be surveyed is divided into a earth surface is in an arc of a great circle. This is not a network of triangles and the length of its sides measured straight line measurement. in the field and no angular measurements are required is known as Triangulation. The survey in which the earth surface is assumed as plane and the curvature of earth is ignored is known as Classification of surveying (Fig 2) plane surveying. Marine/Hydrographical survey: It is the survey, which The survey in which the curvature of earth is taken into deals the objects under the water. account is known as Geodetic surveying. This is done by Aerial survey: It is the survey in which to collect the Great Trignometrical Survey (GTS) of India. details of cyclonic affected areas, flooded areas etc. is done by aeroplane in air. Area less than 260 sq.km is treated as plane. Astronomical survey: It is the survey, which deals with From the Fig 1 the stars in the sky. Land survey Topographical survey: It is the survey to determine the natrual and artificial features on the earth. Cadastral survey: It is the survey which deals the addi- tional details of the boundaries of fields, houses etc. City survey: It is the survey which deals the layout plots, roads, watersupply and severage systems. Engineering survey: It is the survey which deals with determining the quantities and collecting the data for the design of engineering projects such as roads, dams etc. reservoirs or work in connection with water supply severage As per plane surveying, the straight distance between B etc. and C will be 18km As per Geodetic surveying, the curved distance between B and C will be 18.1km 54 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12  27 Mine survey: It is the survey which deals in exploring To fix the position of new stations, atleast two independ- mineral wealth such as gold, coal, copper etc. with in the ent positions are required. earth’s crust. The new stations are fixed from points already fixed by Geological survey: It is to determine the different strata in the earth’s crust. – linear measurements Archaeological survey: It is the survey deals in unearth- – angular measurements ing the relics of the past. – both linear and angular measurements Military survey: It is the survey for determining points of strategic importance both offensive and defensive. PQ is the reference line and R is the point to be located. Principles of surveying From Fig 4a, the distance PR and QR can be measured All survey works are based on the following two basic and the point R can be plotted by swinging two arcs with principles the same scale in which PQ has been plotted. 1 To work from whole to the part. From Fig 4b, a perpendicular RS can be dropped on the line PQ and lengths PS and SR are measured. Then the 2 To locate a point with respect to two reference points. point R can be plotted by using set square. 1 To work from whole to the part (Fig 3) From Fig 4c, the distance QR and angle PQR can be measured as α. Then the point R is plotted by means of To survey an area, it is to establish the main control points a protractor or trignometrically. with great precision. From Fig 4d, in this method angle RPQ (β) and RQP (α) The main idea is to are measured by using an angle measuring instrument, then point R is plotted either by protractor or solution of – prevent the accumalation of errors triangle PQR. – control and localise minor errors. From Fig 4e, in this method angle RQP (α) and distance PR are measured. Then the point R can be plotted by 2 To locate a point with respect to two reference using protractor and swinging an arc from P. points (Fig 4) Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12 55  28 Work of a surveyor Taking measurements in the field. Recording field notes. Preparing survey maps, plans and sections. Calculating the areas and volumes. Designing the various structures. Handling of survey instruments. Care and maintenance of survey instruments. Steel Tape (Fig. 5) 1 It is used for accurate work. 5 2 It is lighter weight and easier to handle than the chain. 3 It is 20m or 30m long. 4 It is made from ribbon of steel 16mm wide. 5 The brass handles are provided at the ends of the chain with swivel joint. SUN121265 6 It is wound on an open steel cross or a metal reel in a closed case. 7 The graduations are worked in two ways. 8 It is divided by brass studs at 0.2m and numbered at every 1m in the first portion and the last link is subdi- vided into cm and mm. 9 The graduations are etched as metres, decimeters and centimetres on one side and 0.2m links on the other side. Brass tallies are fixed at every 5 in length. 56 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.12  29 Construction RelatedTheory For Exercise : 1.2.13 Surveyor - Basic Engineering Drawing Types of scales Objectives: At the end of this lesson you shall be able to state the necessity of scales explain representative fraction (RF) list the types of scales explain plain, comparative scales, diagonal scale. Inroduction Full scale Engineering drawings are rarely drawn to the same size An actual length of an electrical switch board of length of the object. In the preparation of drawings of a building, 30mm, is repersented by a 30 mm length on drawing.Then, It is not practically possible to make the drawing to the same size of the building. Here, the drawing is prepared R.F.= Distance on drawing/ Distance on object to the reduced size and it is called reduced scale drawing. = 30mm/ 30mm Thus, the drawings prepared proportionately to the smaller = 1/1 or larger size than the actual size, are siad to be made to a scale. Scale of a drawing may be defined as the ratio of Scale of drawing is 1:1 linear dimension of the same object. Scales used in Scales used to scale drawn large parts in engineering engineering practice are available in sets of 8 or 12 drawings and architecture: scales. same times the required scale will not be available. Then, it is necessary to construct a new scale. 1:40 1:100 Therefore, a convenient scale is always chosen to prepare 1:50 1:150 the darwings of big as well as small object in proportionately 1:65 1:200 samller or larger sizes. So the scales are used to prepare a drawing at a full size, reduced size or enlarged size. 1:80 Representative fraction Typical scale for site plan-unit in m Representative fraction may be defined as the ratio of the 1:500,1:5000 distance between any two points of the object on a 1:1000,1:1000 drawing to the actual distance between the same points of the object and it is abbreviated as R.F. 1:2000,1:20000 Mathematically, Scale need in surveys R.F = distance on drawing/Distance on object 1:50000 1:200000 Reducing scale 1:100000 1:50000 An actual length of 5m of a romm is represented by 25mm Scales used in maps Units in m. length on drawing. Then, 1:1000000 R.F = distance on drawing/Distance on object Recommended scales = 25mm/5m Scales recommended for use on engineering drawings = 25/5 x 100 x 10 are give below = 1/200 Full scale Reduced scale Enlarged scale Scale of drawing is 1: 200 1:1 1:2 10:1 Enlarging scale 1:2:5 5:1 An actual length of a typical terminal strip of 10mm is 1:5 2:1 represented by 50mm length on drawinig. Then, 1:10 R.F. = Distance on drawings/ Distance on object 1:20 = 50mm/10mm 1:50 = 5/1 1:100 Scale of drawing is 5:1 1:200 57 Civil Engineers and Architect generally use reduced scales Every scale should have the following salient features: 30 while Mechanical and Electrical Engineers use both – The zero of the scale is placed at the end of the first reduced and enlarged scales according to the need of the division from left side. problems. – Form zero, mark further divisions are numbered Mertric Measurements towards right. Table 11:1 – Sub - divisions are marked in the first division from 10 millimeters (mm) 1 centimeter (cm) zero to left side. 10 centimeter (cm) 1 decimeter (dm) – Names of units of main divisions and sub divisions should be stated/printed below or at the end of the 10 decimeters (dm) 1 meter (m) divisions. 10 meter (m) 1 decameter (dam) – Indicate the ‘RF’ of the scale. 10 decameter (dam) 1 hectometer (hm) Example of construction of a plain scale to measure 10 hectometer (hm) 1 Kilometer (km) metres and decimetres. RF = 1/50 and to measure up to Types of scales 8 metres. Minimum standard length of scale = 15cm. The length of the scale = RF x maximum length to be – Plain scale measured = 1/50 x8x100cm = 16cm. – Diagonal scale Length of 16 cm is divided into 8 equal parts or major – Vernier scale divisions each representing one metre. If each major – Comparative scale division is divided into 10 sub - divisions each sub - division will represents one decimetre. – Scale of chords (for angles) A distance of 6.7 m will be shown as in the Fig 1. To construct a scale the following information is essential Comparative scales (Fig 2) : Comparative scale is a RF of the scale graphical divice to compare or convert one variable into – Units which it must represent example mm, cm, m, ft another. It compares two similar units in different systems. inches etc. For example meters, yards,kilometers, miles, temperature in degrees, centigrades and Fahrenheit etc. – the maximum length it must show Fig 2 shows the construction of a comparative scale to – Minimum length of the scale = RF x the maximum convert Fahrenheit (F) into Celsius (Centigrade - C) and length required to be measured. Celsius into Fahrenheit. Plain scales (Fig 1) : Scales are drawn in the form of – The line AB (15 cm) is divided equally into 10 equal rectangle, of length 15cm (can be upto 30cm) and width parts. 5mm. It is divided into suitable number of parts. The first part of the line is sub - divided into samller units as – Division on the top side of the scale is divided into 10 required. equal sub - divisions. Each sub - division is representing 1°C. – Division on the bottom side of the scale is divided into 58 Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.13  31 18 equal sub - divisions. Each sub - division is called 1°F. – Datum of ‘F’ side scale is starting with 32°F instead of 0. – Conversion from °C to F or vice - versa can be found out directly from the scale. – 10° C equivalent reading of F scale = 50°F – 25° C equivalent reading of F sacle = 77°F – For the verification of the conversion using the scale use the fllowing formulae. C = (F - 32) x 5/9 Join one of the diagonal AC. F = (C x9/5) + 32 Join parallel line cuts the diagonal at a,b.......j. Diagonal scale : Plain scales cannot be used for taking Distance 1 - a is 1th/10 of AB = 0.1AB smaller measurement. The distance between the Distance 2 - b is 2 th/ 10 of AB = 0.2 AB consecutive divisions on a plain scale , at best can only be 0.5mm. In other words, the smallest measurement that Distance a - i is 9th/ 10 of AB = 0.9 AB can be taken. Using a plain scale of RF 1:1 is 0.5mm. If Distance b - ii is 8 th/ 10 of AB = 0.8 AB the RF of a plain scale is 1:5, the smallest measurement such a scale can take is 2.5 mm (0.5 mmx5). If AB is 1mm then 1 - a will be 0.1 mm and 2 - b will be 0.2mm. To overcome this limitation two different types of scales are employed. They are Similarly a - i will be 0.9 mm and c - iii will be 0.7mm. – Diagonal scale Parallel lines on both sides of the diagonal can be considered for measurement. – Vernier scale Priniciple of diagonal scale : Diagonal scale relies on a “ diagonal” to divide a small distance into further equal parts. Principle of diagonal scale is based on the principle of similar triangles. Example : A small distance AB is to be divided into 10 equal parts using diagonal scale. AB is the line to be divided into 10 equal parts. Diagonal scale is shown in the Figure 3. Side AD is the line to be divided into 10 equal parts 1 to 10. Parallel lines are drawn to AB from points 1,2.......10. Construction - Surveyor (NQSF Level -5) R.Theory For Exerise : 1.2.13 59