AutoCAD 2D-I Module 1: Introduction to Drawing Tools PREPARED BY IAT Curriculum Unit January 2011 Institute of Applied Technology, 2011
Module 1: Introduction to Drawing Tools Module Objectives After the completion of this module, the student will be able to: Identify and describe the use of engineering drawing equipment Recognise different methods of laying out engineering drawing papers. Demonstrate the use of scales. Produce a simple drawing paper layout including border and title block. Module Contents 1 Introduction... 2 2 Drawing instruments... 2 2.1 Drawing Boards... 2 2.2 T-Square... 3 2.3 Set Square... 3 2.4 Pairs of Compasses... 3 2.5 Protractor... 3 2.6 Ruler... 4 2.7 Drawing pencils... 4 2.6 Eraser... 4 2.8 Circle template... 4 3 Drawing Paper... 5 3.1 Sizes of the drawing paper... 5 3.2 Scales... 5 3.3 Layout of the drawing paper... 5 3.4 Line type... 6 4 Technique of Lettering... 7 5 Activities... 8 5.1 Class Activities... 8 5.2 Homework... 8
1 Introduction Technical drawing is the study of the procedures, tools, supplies, skills and techniques used to record and communicate the shape and size of a product. Every product we have today (e.g. cars, houses, machines, etc ), began as an "idea" in some person's head. Before these "ideas" became products, they had to be drawn on paper so as to show what the idea looks like from different directions, Fig.1.1. Fig.1.1: Burj Al Arab- Dubai 2 Drawing instruments To prepare a drawing, one can use manual drafting instruments as shown in Fig.1.2, or computer-aided drafting (CAD). If the drawing is made without either manual instruments or CAD, it is called a freehand sketch. The following instruments are essential and should be available to produce a good quality technical drawing. Fig. 1.2: Manual Instruments. 2.1 Drawing Boards Drawing Boards can range from simple boards, like the one shown in Fig.1.3, to complicated drawing machines that would be used in engineering drawing office. The surface of the board should be dusted and smooth. Fig. 1.3: Drawing Board 2 Module 1: Introduction to drawing tools
2.2 T-Square T- Square is composed of a long strip, called the blade; it is placed on the drawing board and provides a constant horizontal edge. The T-square is shown in Fig.1.4. Fig. 1.4:T-Square 2.3 Set Square Set Squares are best made from transparent plastic. The two standard set squares that are commonly used are 30/60 and 45/45 degrees triangles as shown in Fig 1.5. 45/45 triangle 30/60 triangle Fig. 1.5:Set Square 2.4 Pairs of Compasses There are basically two types of compasses 1. Pencil compasses which are used to draw circles. Circles up to 300 mm diameter are drawn using a large radius compass. 2. Spring bow compass which is used to draw circles of 50 mm diameter or less. (Fig.1.6). 2.5 Protractor Fig. 1.6:Compasses Protractors measure angles other than those obtained by the set squares and found in half circle or full circle types, Fig. 1.7. Fig.1.7: Protractors Module 1: Introduction to drawing tools 3
2.6 Ruler A 300 mm ruler with one edge marked in centimeters and millimeters is necessary, Fig.1.8. In a fully equipped drawing machine, horizontal and vertical rulers with graduations in mm or inches are attached to the drafting head. Fig.1.8: Ruler 2.7 Drawing pencils Pencils have nine grads of hardness from H to 9H and seven grades of softness from B to 7B as shown in Fig. 1.9. Fig.1.9: Pencil lead grades. 2.6 Eraser Erasers are available in different hardness and are used to erase pencil work. The common eraser used is a block-shaped vinyl eraser. (Fig.1.10). Fig.1.10: Eraser 2.8 Circle template Circle templates are useful for drawing small circles quickly and to join lines with a radius, A circle template is shown in Fig.1.11. Fig.1.11: Circle template 4 Module 1: Introduction to drawing tools
3 Drawing Paper 3.1 Sizes of the drawing paper Drawing paper is available in A series, B series, and rolls of the International Organization for standardization (ISO), but series A is preferred. Paper sizes for series A are based on the A0 size, which has an area of 1 square meter. An A0 size sheet can be divided up evenly into the various other sizes (A1, A2, A3, A4 ) simply by halving the sheet on the long side in each case. As shown in Fig. 1.12. Fig. 1.12: Paper Sizes 3.2 Scales In order to produce drawing showing components in detail or as plans it is often necessary to use a scale. This can increase the size of the drawing in comparison to the real size of the component. Some of the recommended scales are listed below: Enlargements scales: 2:1 20:1 50:1 10:1 Full (same) size: 1:1 Reduction scales: 1:2 1:10 1:20 1:100 3.3 Layout of the drawing paper Drawing sheets of all sizes have standard layout. It is usual for each sheet to be provided with a drawing frame a short distance from the edge of the paper as shown in Fig.1.13. Each drawing sheet has to be provided with a title block which represents the general information source for a drawing. It is normally placed in the bottom and at least contains the title of the drawing, the name of the draftsman, the scale, and the date. Module 1: Introduction to drawing tools 5
Drawing frame 15 BORDER 330 265 200 Title block 100 NAME: TITLE: SECTION: DATE: SCALE 15 Fig 1.13: Layout of the drawing paper. 3.4 Line type Fig. 1.14 shows the types of line which are commonly used in engineering drawings such as visible lines, hidden lines, center lines, dimension lines, extension lines, and leader lines. Fig. 1.15 shows an application for the use of different types of lines. LINE Description Application Continous thick Continous thin Dashed thin Chain thin Visible outlines Dimension lines Projection lines Leader lines hatching Hidden outlines Circle center lines Fig.1.14: Line types and their description 6 Module 1: Introduction to drawing tools
130 HIDDEN UOTLINES (DASHED LINE) 70 20 OUTLINE (CONTINOUS THICK) 10 5 15 20 30 DIMENSTION LINE (CONTINOUS THIN) CENTER LINE (CHAIN THIN) 50 110 Fig 1.15: The use of different line types in engineering drawing. 4 Technique of Lettering Printing increase the information that is provided on a drawing. Printing must be clear and neat so 5 that it is easy to read. Use guide lines 5 mm Fig. 1.16: Guide lines for apart as illustrated in Fig. 1.16. printing. These guide lines can be used to make sure that all letters and numbers have the same size. Always print using capital letters. All letters and numbers should touch the top and bottom guide lines. Guide lines should be 5 mm apart as explained earlier. An example for lettering technique is shown in Fig 1.17. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Fig. 1.17: Printing numbers and letters. Module 1: Introduction to drawing tools 7
5 Activities 5.1 Class Activities Draw the objects shown below in full size using different drawing tools such as compasses, set squares and tee square. Use an A3 sheet to create the drawing with the same layout shown below. 1? 100 2 R30 80 3 4 110 R15 R20 R15 80 R35 50 80 40 30 NAME: TITLE: SECTION: DATE: I.D.No. 5.2 Homework Draw the objects shown below in full size using different drawing tools such as compasses, set squares and tee square. Use an A4 sheet for each of the following objects 8 Module 1: Introduction to drawing tools
1. 45 45 2. R45 120 50 20 50 20 15 30 60 3. 120 15 15 60 30 60 Module 1: Introduction to drawing tools 9
Student notes 10 Module 1: Introduction to drawing tools