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TECHNICAL DRAWING
The document provides an introduction to technical drawing and discusses the difference between technical drawings and artistic drawings. It notes that technical drawings aim to convey technical information to enable manufacturing of an object, while artistic drawings aim to provoke emotions. The document then discusses common drawing materials used for technical drawings such as pencils in various hardness grades and propelling pencils.
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TECHNICAL DRAWING
- 1. UNIT 2: “TECHNICAL DRAWING” 1.- INTRODUCTION. A technical drawing is a form of graphic communication. This type of drawing is used in the transformation of an idea into physical form. The process of creating a technical drawing is called drafting or technical drawing. A person who does drafting is known as a drafter. A technical drawing differs from a common drawing by how it is interpreted. A common drawing can hold many purposes and meanings, while a technical drawing is intended to concisely and clearly communicate all needed specifications of a created object or objects. Difference between technical drawing and artistic drawing: TECNHNICAL DRAWING ARTISTIC DRAWING The page is signed to become responsible The page is signed to become responsible of of the designed object. the artistic value from the picture. Paper sizes are standardized formats. Picture sizes are chosen by the painter. Rules are fulfilled. There are no rules. Technical drawings are only done in Painters usually use many colours. black. Only have one possible interpretation. Have many possible interpretations. Have measurements. Have no measurements. All of the above can be summarized by defining artistic design as "drawing done with the intent or purpose to provoke emotions or feelings", and technical drawing as "drawing that aims to convey technical information about an object to manufacture." 2.- DRAWING MATERIALS. The instruments of drawing are the tools we use to make technical drawings. The most important tools are: - PENCIL. It is a drawing instrument that consist of a cylinder of wood that contains a stick of graphite. According to the hardness of the graphite, the pencil can be classified by a number or by numbers and letters. Look at the table: HARDNESS NUMBERS 0 1 2 3 4 5 6 7 8 9 LETTERS 7B 6B 5B 4B 3B 2B B HB F H 2H 3H 4H 5H 6H 7H 8H Soft Middle Hard Extra-Hard Drawing Pencils are a basic requirement of any graphics course. You need a number
- 2. ranging from 2Bto 2H. These letters refer to the hardness of the pencil lead. When sketching, a soft lead such as 2B can be used to produce quick drawings and shading. On the other hand, when drawing precisely a 2H or even a harder pencil such as a 4H is ideal. This type of pencil keeps its sharp edge for longer and produces very fine lines: - PROPELLING PENCIL. It is an instrument of drawing similar to a pen, but it contains a graphite stick like a pencil and it has the same use as a pencil. Refillable pencils A refillable pencil is very useful especially if you are making a drawing that needs a constant thickness of line. The refills are available in a range of thicknesses and in either hard or soft leads. Thickness of line 0.5, 0.7, 0.9, 1.1, 1.3, y 1.6 mm. 010009000003f67601000000d3d4000000001610000026060f002220574d46430100000 000000100258e000000000b00000000200000f8210100f8410100010000006c00000000 0000000000000024010000db00000000000000000000006a2800004a1e000020454d460 0000100f84101000c000000010000000000000000000000000000000005000020030000 c40100001a010000000000000000000000000000e3e306006e4e0400460000002c00000 020000000454d462b014001001c000000100000000210c0db0100000060000000600000 00460000008424000078240000454d462b224004000c000000000000001e4009000c000 00000000000244001000c000000000000003040020010000000040000000000803f2140 07000c0000000000000008400005d0230000c42300000210c0db0100000000000000000 00000000000000000000001000000ffd8ffe000104a46494600010101004800480000ffdb 00430006040506050406060506070706080a100a0a09090a140e0f0c101714181817141 6161a1d251f1a1b231c1616202c20232627292a29191f2d302d283025282928ffdb00430 10707070a080a130a0a13281a161a282828282828282828282828282828282828282828 2828282828282828282828282828282828282828282828282828282828ffc000110800a 500dc03011100021101031101ffc4001c00000202030101000000000000000000000203
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- 21. - TECHNICAL PENS(fountain pens). A technical pen is a specialized instrument used to make lines of constant width for architectural, engineering, or technical drawings. It has been also generally called "rapidograph", although that particular name has officially remained a proper name for a line of products made by German company Rotring. It is used for making drawings with ink. 010009000003f62102000000c53c010000001610000026060f002220574d46430 100000000000100ef30000000000f0000000020000064a7010064c70100010000006c00 000000000000000000000c010000b800000000000000000000001a25000078190000204 54d460000010064c701000c000000010000000000000000000000000000000005000020 030000c40100001a010000000000000000000000000000e3e306006e4e0400460000002 c00000020000000454d462b014001001c000000100000000210c0db0100000060000000 6000000046000000581f00004c1f0000454d462b224004000c000000000000001e40090 00c00000000000000244001000c00000000000000304002001000000004000000000080 3f214007000c0000000000000008400005a41e0000981e00000210c0db0100000000000 00000000000000000000000000001000000ffd8ffe000104a46494600010101006400640 000ffdb00430006040506050406060506070706080a100a0a09090a140e0f0c101714181 8171416161a1d251f1a1b231c1616202c20232627292a29191f2d302d283025282928ffd b0043010707070a080a130a0a13281a161a282828282828282828282828282828282828 2828282828282828282828282828282828282828282828282828282828282828ffc0001 10800c1011803011100021101031101ffc4001c00000104030100000000000000000000 00000104050602030807ffc400421000010303020306030406080701000000010002030 4051112210631410713225161718191a1081432b123244252c1d11533627282b2e1f117 2526345392a2c2ffc400190101000301010000000000000000000000000102030405ffc4 0024110101000202010403010101000000000000010211213103041232412251611333 52ffda000c03010002110311003f00ea14020540201008040201008040a8040040201008 0402054088040a811008040201008040201008110050220540201008040203080f74020 1008040a80402010080402054020d4e9436a190e377b1cf07d881ff00e820d8815008110 080402010081100804088040a80402047bdb1c6e7bce1ad1925079af13f68d4f4171348e a9929dc319869e2124a41e5a9eef0b3db0573e5e7fa8d678f691e0bbd53f133aad9df5da17 d3e925d2d434eac93cb4803a7928ff4feabedd26ae12ff47575251b2e55eea9a9cf74c2c6ca ddbcf201c7c55ae565d6d1adb7c375960a9929ebc42f31805ef84e1cc0791730ee07a8c85 79e4e754b8fe9320820107208d88eab4542010081adc6e1456c844d72aca6a3889c07d44 ad8c13ee4a0856f1cf0c388d37ba47e4e0169247cc04dc4ea9fd171159aba56454b74a392 579c363ef435cef669c1288d692dcba201008040208fafaba6a4b951beaea21818f8a5634c b206027319c0cf3e4a2890c838230429020102a0440201008040204402044020102a010 33bbbcb2db50e1b1d3854ceeb1a9c66eb973898c955c657031b1f2112e30c6ea3b01e4b8 63af1e9e8dd9a554b699aae6aca2ae6472b99a1c299ee1800f90f557fd32bfd5c5d72a7ba7
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- 38. 39c739c737b6f7b6f5a6b5a6b396739673967396718631863186339671863396739675a6 b39675a6b5a6b7b6f5a6b7b6f7b6f9c737b6f9c739c739c739c73bd77bd77bd77bd77de7b bd77de7bbd77de7bde7bde7bde7bde7bde7bde7bde7bde7bbd77de7bbd77bd77bd77bd77 9c73bd779c739c737b6f7b6f7b6f7b6f5a6b39673967734ee71cc61c0721c518c418e41ca 314c418c418e51c061d0721e61ce61c071d492549258b2d49252821292109211863ff7f9 c73bd77de7bbd77de7bde7bde7bde7bde7bde7bde7bff7fde7bde7bde7bff7fde7bde7bde7 bde7bbd77de7bbd77de7b9c73bd779c737b6f5a6b39671863734e4a29a514a314c318a31 4c41cc418c518c418e51ce61cee39734ece398b2db456ff7fff7fff7fff7fde7bff7fff7fff7fff7 fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7ff f7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fff7fde7bff7fff 7fff7fde7bff7fde7bde7bde7bff7fdd7bde7bbe77de7b7a6f14673367356b1467346b346b3 56b14671467146735671467356b1467356b356b356b1467566f356b356b1567356b1567 356b356b366b3567356b1567366715673667156715671567356716677a6 Rapidograph by Rotring - TEMPLATES. Templates are special rulers which are used to draw symbols and do complicated figures. - THE GRADUATED RULER. A ruler is possibly one of the most important pieces of drawing equipment. Rulers are used to measure distances with lines. . - SET SQUARES Set Squares are used to draw accurate angles. The most common are 45 and 60/30 degrees.
- 39. A Set hasan angle of 90 degrees and two 45 degree angles. It is used to make parallels, perpendiculars and draw angles. A Set Square has one 90 degree angle, one 30 degree angle, and one 60 degree angle).
- 40. - PROTRACTOR A protractoris used to measure angles. A typical protractor is a semi-circular piece of plastic with 180 degrees printed around its curve. 3.- PAPER. Paper formats are the normalized sizes which we must use to do technical drawings. The normalized (or standardized) formats are: DIN A0, DIN A1, DIN A2, DIN A3, DIN A4, DIN A5 y DIN A6. The following rules are reflected in the following tables: a.- A format has twice size of the following format. b.- The length of a format is twice the width of the following format. c.- The width of a format is the same as the length of the following format. FORMAT LONG WIDE DIN A0 1188 840 DIN A1 840 594 DIN A2 594 420 DIN A3 420 297 DIN A4 297 210 DIN A5 210 148 DIN A6 148 105
- 41. 4.- LABELLING. Labelling isthe set of letters and numbers that accompany a technical or flat drawing. Labelling is standardized, in other words, the letters must be of fixed proportions, so that no confusion can arise in the interpretation of the data. We only imitate this kind of writing as accurately as possible. It is used basically on two parts of the drawing, in the title box and the bounding. 5.- STANDARDIZATION. Standardization is the set of rules or standards to follow when making a technical drawing or plan. Paper formats, the hardness of the graphite, production and placement of hearings or views, appropriate scales, the marking, labelling, line types, symbols, etc. All rules that exist are included in the drawing standards of each country, although different rules have been unified to an international standard. Some rules of some countries are U.N.E. (A Spanish standard), D.N.I. (German standard), U.N.I. (Italian standard), I.S.O. (International standard). 6.- TYPES OF LINES. The types of lines to be used in technical design is standardized, so each has a specific application. The types of lines that are used in industrial design and its applications are following: Continuous thick: C Contours and edges are visible in views and perspectives. On the margins of drawing and painting or wall jack. Continuous thin: In auxiliary dimension lines and dimension. Freehand: In drawings and sketches.
- 42. Dashed: In contourand hidden edges. Dash-dot: . . . . . . . . In lines of symmetry. 7.- CROQUIS AND SKETCH. CROQUIS SKETCH A sketch is a rapidly executed freehand drawing that is not intended to be a finished work, often consisting of a multitude of overlapping lines and there are no rules about how to sketch. The purpose of a sketch is to convey the best possible idea without going into details. A Croquis drawing is a quick and sketchy drawing with measurements (bounded) and proportioned. We usually use views. 8.- STANDARD VIEWS. Technical drawing consists of representing objects which are three dimensional in the two dimensions on paper. To solve this problem, one of the tools used is viewpoint. We call a “View”, the shape of an object when viewed from a specific site, for example, the shape of the object from a certain position. As reflected in the next drawing, there are six possible views that can be taken of any object. For a piece to be perfectly represented, we must follow these steps: 1. Choose an elevation a view that offers further information about the shape of the piece. This view is the main view. Any view can be chosen as elevation.
- 43. 2. We candraw up to a total of six views, although if we draw the elevation, the left side and the plant it is enough. 3. The arrangement of the views is similar to the following figure: This is the image of an object in a box, with views of the object projected from the direction of sight onto walls using first-angle projection. D The views are positioned relative to each other according to either of two schemes: first-angle or third-angle projection. In each, the appearances of views may be thought of as being projected onto planes that form a 6-sided box around the object The name of the views: - View A: Elevation is an orthographic projection of a 3-dimensional object from the position of a horizontal plane beside an object
- 44. - View B:Plan view or ground plan is defined as a vertical orthographic projection of an object on a horizontal plane, like a map. It is viewed from below the elevation. - View C: Right side View. It is viewed from the left of the elevation. - View D: Left side View. It is viewed from the right of the elevation. - View E: Top view. It is viewed from over the elevation. - View F: Rear view. It is viewed from the right of the left side. * In the United States of America this is done in a contrary manner. 8.1.- ELEVATION, GROUND PLAN (plan view), AND SIDE VIEW. When we draw an Orthographic view of the front of an object it is called an ELEVATION. When we draw an Orthographic view of the top of an object it is called a GROUND PLAN. When we draw an Orthographic view of the profile of an object it is called a SIDE VIEW.
- 45. • We draw a LEFT SIDE VIEW to the right of the elevation. • We draw a RIGTH SIDE VIEW on the left. Ground line 9.- BOUNDING. An orthographic drawing is only complete when measurements, scale, and orthographic symbols are added. To place dimensions on a multi-view drawing: Add measurements. Study the way these have been drawn on the front, side and plan views. It is very important to add measurements when drawing accurate orthographic or working drawings. An orthographic drawing is usually the last drawing before manufacture and so dimensions must be clearly presented and understood. Dimensions can also be applied to simple sketches and designs as they help anyone looking at these drawings to understand the overall size or scale. However, dimensions are usually drawn in a particular way and some examples are shown below: The dimension line has arrow heads and the dimension text is positioned above the line and is drawn using the current text style. (Continuous thin line).
- 46. The extension lineis a line used to visually connect the ends of a dimension line to the relevant feature on the piece. Extension lines are solid and are drawn perpendicular to the dimension line. (Continuous thin line). A leader line is a thin line with an arrow head that is often positioned at an angle and is used to tie a dimension to a feature, especially when there are space limitations. A Note is an additional instruction or general comment added to a blueprint. Notes contain information about the material, finish, tooling, tolerances, etc. A Center Line is a line used to define the center of a symmetrical part. Center lines consist of alternating long and short dashes. chain thin The main dimensioning rules are: 1) The measurements are made in millimeters and focused on the dimension line and
- 47. never write theunits. If at a dimensioned drawing is created with other units (cm, m) we will post a note in the lower corner, near the title box. 2) The benchmark figures (well labeled) are supported (without touching) the dimension line, to read from the normal position of the plane (horizontal dimensions) and from the right (vertical dimensions). 3) The arrows will be elongated and black, reaching the tip of the extension lines. 4) Extension lines and dimension lines should not be cut. 5) Extension lines protrude approximately 2 mm. from dimension lines. 6) When we can, we will draw out the dimensions (text) of the piece. 7) When a measurement is small, the arrows will be placed on the outside. If there are many small measurements together, the arrows are replaced by dots. 8) The dimensions must not be repeated, some measurements can be obtained by the addition or subtraction of the others. 9) To see if a piece is well bounded, we think about if we could build it. 10) There are some symbols used in bounding to save us the trouble of drawing more views. The diameter sign "φ" represents a circular shape when it is not visible in the view. The same happens with other symbols like the square. “We can say that mastering the language of drawing, learning) the different types of drawings, achieving proficiency in the drawing of view), implementing the type of line required i)each case, meeting the standards and bounding correctly, can only be achieved by practice. “So, all that we have learned about drawing will only be useful if we practice by making drawings”. 10. PERSPECTIVE. A second way to represent an object in three dimensions (height, width and depth) in the two dimensions of the paper is known as perspective. To make these representations, technical drawing uses a system of three axes, indicating the three directions in which the object will be drawn. To represent an object in three dimensions we use the isometric perspective or the cavalier perspective, although this course we will only study the cavalier perspective. 10.1. CAVALIER PERSPECTIVE. This perspective has three axes. The X axis (width) and the Z (height) form a right angle, and the Y axis (D) form a 135 degree angle with both (X and Z). All edges that follow the direction of the height (Z axis) should be vertical and parallel. All edges that follow the direction of the width (X axis) are horizontal and parallel.
- 48. The same appliesto the edges that follow the direction of the depth (Y axis). In the following figure we can see how the set squares are placed for drawing a figure in cavalier perspective more quickly and easily. When we draw the cavalier perspective of a piece we must take into account a very important rule, “the dimensions of the edges parallel to the axis Y (depth) are subject to a reduction coefficient K = 0.5”, ie, the edges should be drawn with (the) half of its actual measurement. If we do not reduce this axis (Y), the shape of the piece gives the feeling of having a size much larger than reality. For example: If the normal size is 25 mm. in depth (Y axis), we must reduce this axis (Y) before drawing it. The new measurement in Y is: 25 mm x K = 25 x 0,5 =12,5 mm. Fig. 1 (Normal size. Without reduction factor). Fig. 2 (With reduction factor) 11. THE SHEET OF DRAWINGS OR PLANS. We have talked about the fact that in technical drawing we cannot use any type or size of paper. There are also rules for the presentation of any technical drawings or, in other words, in developing a plan. In DIN A4, that will be our normal size drawing, we will draw a box with the following ranges: - On the left side 25 mm., in order to bind the paper if necessary. - At the top, bottom and on the right side 5 mm. At the bottom of the box we will draw another box divided into other boxes which we will call “title
- 49. box”. The roleof the title box is to be able to place in the drawing, in an orderly manner, all the information related to it: who has drawn it, date, high school name, etc. (In your book you can find a title box drawn and bounded). DICTIONARY. For the development of our technical dictionary, you have to look for the meaning of these words, using this book first, in case you do not find them here, ask your family or look them up in a dictionary, but remember you have to write the definition with your own words. It’s not worth copying what it is written in your dictionary. Technical drawing - Set – DIN A4 - dashed line - thin continuous line – Title box - Standardization - Bounding - Sketch – Elevation.