basics of engineering drawing by rishabh natholia

POORNIMA COLLEGE OF ENGINEERING

RISHABH NATHOLIAMECHANICAL ENGINEERUNIVERSITY- RTU KOTAhttps://in.linkedin.com/in/rishabhnatholia

ENGINEERING DRAWING

CHAPTERSINTRODUCTION TO ENGINEERING DRAWINGDRAWING STANDARDSDRAWING SHEETTRADITIONAL DRAWING TOOLSCALESLINESLETTERINGPROJECTIONSECTIONINGDIMENSIONING

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INTRODUCTIONAn Engineering Drawing is a type of technical drawing, used to fully and clearly define requirements for engineered items, and is usually created in accordance with standardized conventions for layout, nomenclature interpretation, appearance size etc.4https://in.linkedin.com/in/rishabhnatholia

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DRAWING STANDARDStandard are the set of rules that govern how technical drawing are represented.Drawing Standard are used so that drawing convey the same meaning to everyone who reads them.Different countries use different standards according to there ease.In India we follow IS (Indian Standard) which is some what like JIS system

IS: 1071 I-1983 Sizes of Drawing SheetIS: 9609 (Part 2)1985 Lettering on Technical Drawing IS: 10713-1983 Scales on Drawing6https://in.linkedin.com/in/rishabhnatholia

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JIS STANDARD PRACTICES8


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DRAWING SHEEThttps://in.linkedin.com/in/rishabhnatholia

DRAWING SHEET10

Sheet SizeMarginEdge LineBorder and FrameOrientation MarkGrid ReferencesTitle BlockFolding Sheet


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Example of Drawing SheetMarginUntrimmed SizeTrimmed SizeMargin LineOrientation MarkTitle BlockGrid Reference FrameBorderhttps://in.linkedin.com/in/rishabhnatholia

SHEET SIZE12This section specifies sizes of blank and pre-printed drawing sheets for use with all technical drawings in any field of engineering. There are various standards for paper size such as A series, B series, C series.

Series A (ISO 216) is taken as standard all over the world A0 size defined to have area of 1 square meter.The length divided by the width is 1.4142.Each subsequent size A(n) is defined as A(n-1) cut in half parallel to its shorter sides.

The area of B series sheets is thegeometric meanof successive A series sheets. The international standard for envelopes is the C series ofISO 269.


Series A Paper Size (ISO 216)

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Inprinting,bleedis printing that goes beyond the edge of the sheet beforetrimming.Gives the printer a small amount of space to account for movement of the paper.RA stands for "raw format A" and is conceptually defined as being 105% of theA series size.SRA stands for "supplementary raw format A" and is conceptually defined as being 115% of the A series size

14Untrimmed Paper

UNTRIMMED V/S TRIMMEDhttps://in.linkedin.com/in/rishabhnatholia

MARGIN AND ORIENTATION OF PAPER15


16This section covers methods of folding of drawing prints.All large prints of sizes higher than A4 are folded to A4 sizes.The title blocks of all the folded prints appear in topmost position.The bottom right corner shall be outermost visible section and shall have a width not less than 190 mm.FOLDING OF DRAWING PRINTSTYPES OF FOLDFolding of prinits for Filing or Binding

Folding of prints for storing in Filing Cabinet


Folding of prinits for Filing or Binding17


Folding of prints for storing in Filing Cabinet18


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TRADITIONAL DRAWING TOOLSDrawing TableDrawing SheetDrafting TapePencilEraserSharpenerDrafterScaleSet-SquareT-SquareCompass21https://in.linkedin.com/in/rishabhnatholia

22Drawing Instruments or tools are used to prepare neat and accurate drawings.To a greater extent, the ac-curacy of the Drawings depends on curacy of the Drawings depends on the quality of instruments used to prepare them.The following is the list of Drawing Instruments and other materials required

Drawing Board Drafter (Drafting machine) Set Squares Protractor Drawing Instrument Box Drawing Sheet Drawing Pencils Drawing Pins/ClipsDRAWING TOOLS

Drawing BoardDrawing board is made from strips of well seasoned soft wood generally 25 mm thick. It is cleated at the back by two battens to prevent warping.One of the shorter edges of the rectangular board is pro One of the shorter edges of the rectangular board is pro-vided with perfectly straight ebony edge which is used as working edge on which the T edge on which the T-square is moved while making Drawings square is moved while making Drawing23

PENCIL24


The difference is seen in the type ofleadis in the pencil. The hardness written as H, Black the mark the lead makes written as B.The pencil No. 2(HB) pencil stands in middle. The hardest lead in a pencil is a 9H pencil, the blackest lead is a 9B pencil.

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TRY TO NAME THESEhttps://in.linkedin.com/in/rishabhnatholia

SCALES26

SCALESRatio of the linear dimension of an element of an object as represented in the original drawing to the real linear dimension of the same element of the object itself.Full Size - A scale with the ratio 1: 1.Enlargement Scale - A scale where the ratio is larger than 1 :1. It is said to be larger as its ratio increases.Reduction Scale - A scale where ratio is smaller than 1: 1. It is said to be smaller as its ratio decreases.

SCALE 1 : 1 for full sizeSCALE X : 1 for En-largement scaleSCALE 1 : X for Reduction scales27https://in.linkedin.com/in/rishabhnatholia

In all cases, the selected scale shall be large enough to permit easy and clear interpretation of the information depicted.Details that are too small for complete dimensioning in the main representation shall be shown adjacent to the main representation in a separate detail view (or section) which is drawn to a large scale.The scale to be chosen for a drawing will depend upon the complexity of the object to be depicted and the purpose of the representation.28

Scales for Use on Technical Drawingshttps://in.linkedin.com/in/rishabhnatholia

LINES29

LINESThis section specifies the types of lines, their thickness and application for use in technical drawings.Lines on an engineering drawing signify more than just the geometry of the object and it is important that the appropriate line type is used.

Line ThicknessLine StylePrecedence of line

30PROPERTIES OF LINEhttps://in.linkedin.com/in/rishabhnatholia

Line Thickness31

Line Style


Precedence of line32


TYPES OF LINE33


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LETTERING37Lettering used in engineering drawing is referred to as a Single Stroke, Commercial Gothic.The height h of the capital letter is taken as the base of dimensioningThe lettering may be inclined 15 to the right, or may be verticalLettering in Engineering DrawingTo communicate non graphic information Thus must be written with-LegibilityShapeSpace between words and lettersUniformitySizeLine Thicknesshttps://in.linkedin.com/in/rishabhnatholia

Use of Lettering38


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WORD SPACING41


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WORD SPACINGGeneral conclusion are:Space between the letters depends on the countour of the letter at an adjacent sideGood Spacing creates approximately equal background are between letters.https://in.linkedin.com/in/rishabhnatholia

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SENTENCE SPACING44

Leave space between the words equal to space required for writing a letter O https://in.linkedin.com/in/rishabhnatholia

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DIMENSIONING46Dimension as a numerical value expressed in appropriate units of measurement and indicated graphically on technical drawings with lines, symbols and notes.Units of Measurement: The most commonly used unit for length is the millimeter. In civil engineering and architectural drawing, inch or foot is often used as a unit of length. Angles are shown in degrees.Symbols are incorporated to indicate specific geometry wherever necessary.

Providing information on a drawing aboutDistances (size or functional dimensions)Sizes and positions (location or datum dimensions) of holes, grooves and other features.Details relating to manufacture etc.https://in.linkedin.com/in/rishabhnatholia

FUNCTIONAL DIMENSIONS (FDS)These are dimensions, which directly dictate the functioning of the component. That is a FD is a dimension defined on the basis of the function of the product and the method of locating it in any assembly of which it may form part of, e.g. the diameter of a shaft, the length of a bolt, etc.

47NON FUNCTIONAL DIMENSIONS (NFDS)AUXILLARY DIMENSIONS (FDS)These are dimensions, which do not directly affect the functioning of the component but have to be specified to enable production of that component, e.g. the size of a bolt head.These are dimensions which should not necessarily appear on the drawing but are sometimes included to avoid calculations or when they would provide additional/useful information. ADs are usually written in brackets.CATOGRIES OF DIMENSIONINGhttps://in.linkedin.com/in/rishabhnatholia

DIMENSION TERMINOLOGY48


LEADER LINES AND NOTESLeader (or pointer) line Thin continuous line connecting a note or dimension figure with the feature to which it applies. One end of the leader terminates in an arrowhead or dot.The arrowhead touches the outline while the dot is placed within the object or on the outlineThe other end of a leader is terminated in a horizontal line underlining the note

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RULES FOR LEADER LINEA leader line is never drawn horizontal, vertical or curvedIt is drawn at an angle not less than 30o to the line that it touchesWhen pointing to a circle or arc, it is drawn radially

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ARROWHEADS AND DIMENSION LINE POSITIONINGA dimension line is placed at least 6-8 mm away from an outline and from each other An extension line extends ~3mm beyond a dimension lineArrowhead Placed at each end of a dimension line, its pointed end touches an outline, extension line or a centerline. It is also placed at the end of a leader line

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SYMBOLS AND ABBREVIATIONS USED IN ENGG. DRAWING52


TYPES OF DIMENSIONINGAlignedDimension are aligned with the entity being measured.They are placed perpendicular to the dimension line such that they may be read from the bottom or right-hand side of the drawing sheet.Dimensions are placed at the middle and on top of the dimension lines.

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UnidirectionalDimensions are placed in such a way that they can be read from the bottom edge of the drawing sheet.Dimensions are inserted by breaking the dimension lines at the middle.


PLACING DIMENSION54

METHOD FOR DIMENSIONINGParallel Dimensioning Continues Dimensioninghttps://in.linkedin.com/in/rishabhnatholia

PARALLEL (PROGRESSIVE) DIMENSIONINGAll the dimensions are shown from a common reference line. Obviously, all these dimensions share a common extension line. This method is adopted when dimensions have to be established from a particular datum surfaceSmaller dimensions should always be placed nearer the view. The next smaller dimension should be placed next and so on.

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CHAIN (CONTINUOUS) DIMENSIONING56All the dimensions are aligned in such a way that an arrowhead of one dimension touches tip-to-tip the arrowhead of the adjacent dimension. The overall dimension is placed outside the other smaller dimensions


COMBINED DIMENSIONINGWhen both the methods, i.e., chain dimensioning and parallel dimensioning are used on the same drawing, the method of dimensioning is called combined dimensioning

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CYLINDRICAL DIMENSIONSCylindrical features should be dimensioned by giving their diameters. They should be dimensioned in the views in which they appear as rectangles58CYLINDER OUTER DIMENSION IS ALSO CIRCULAR. CAN BE HOLLOW OR SOLID


DIMENSIONING ARCS59


DIMENSIONING CONICAL FEATURES60

DIMENSIONING WRONG VS. CORRECT


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NOTE that all rules on dimensioning are just guidelines. Use common sense depending on circumstances (i.e. there are no strict rules/regulations on dimensioning)In metric system, all linear dimensions are considered to be in millimetersShow full size dimensions regardless of the scale used in the drawing

Dimension any feature only once (i.e. no repetitions are allowed)Dimension obviously identical features only once62General Hints on Dimensioning


For any query or error feel free to mail me :[email protected]


basics of engineering drawing by rishabh natholia

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