Technical Drawing 8 - 2nd Grading - PDF

Department of Education Region III Division of Pampanga Bro. Andrew Gonzalez Technical High School San Juan, Apalit, Pampanga Technical Drawing 8 Second Grading Developed by: Macy M. Serrano SST-I ...

Department of Education Region III Division of Pampanga Bro. Andrew Gonzalez Technical High School San Juan, Apalit, Pampanga Technical Drawing 8 Second Grading Developed by: Macy M. Serrano SST-I  HOW TO USE THIS MODULE Activities are properly arranged in this module to help you work on your own pace. This module also covers the knowledge, skills and desirable attitude you need in technical drawing. A Pre-assessment precedes the learning activities in each module to determine your learning level and need. The Learning Activity Page gives the sequence of the learning task. This page serves as the road map in achieving the desired objectives. When you are able to accomplish all the tasks required, a post-assessment is given to check if the student is already competent with the specified learning outcome/s and ready for the next task.  What Do You Already Know? PRE-TEST Direction: MATCHING TYPE. Match COLUMN A with COLUMN B. Study the two types and complete the table by matching the numbered orthogonal drawings with the same isometric view. COLUMN A COLUMN B Column A 1 2 3 4 5 6 7 8 9 10 11 12 Column B  What Do You Need To Know? INFORMATION SHEET NO.1 Isometric projection is a method for visually representing three-dimensional objects in two dimensions in technical and engineering drawings. It is an axonometric projection in which the three coordinate axes appear equally foreshortened and the angle between any two of them is 120 degrees. Principle of Isometric Projections It’s a pictorial orthographic projection of an object where a transparent cube containing the object is tilted before one of those solid diagonals of the cube becomes perpendicular to the vertical plane along with the three axes are equally inclined to this vertical plane. The isometric projection of a cube in steps is shown in the below figure-1. Here ABCDEFGH is the isometric projection of the cube. 1- Principle of Isometric Projections The front view of this cube, resting on one of its corners (G), is the isometric projection of the cube. Isometric Drawing Isometric drawing, also called isometric projection, method of graphic representation of three- dimensional objects, used by engineers, technical illustrators, and, occasionally, architects. The technique is intended to combine the illusion of depth, as in a perspective rendering, with the undistorted presentation of the object’s principal dimensions—that is, those parallel to a chosen set of three mutually perpendicular coordinate axes. An isometric drawing is a 3D representation of an object, room, building or design on a 2D surface. One of the defining characteristics of an isometric drawing, compared to other types of 3D representation, is that the final image is not distorted. This is due to the fact that the foreshortening of the axes is equal. The word isometric comes from Greek to mean 'equal measure'. The isometric is one class of orthographic projections. (In making an orthographic projection, any point in the object is mapped onto the drawing by dropping a perpendicular from that point to the plane of the drawing.) An isometric projection results if the plane is oriented so that it makes equal angles (hence “isometric,” or “equal measure”) with the three principal planes of the object. Thus, in an isometric drawing of a cube, the three visible faces appear as equilateral parallelograms; that is, while all of the parallel edges of the cube are projected as parallel lines, the horizontal edges are drawn at an angle (usually 30°) from the normal horizontal axes, and the vertical edges, which are parallel to the principal axes, appear in their true proportions. Drawing of objects are seldom drawn in true isometric projections, since using an isometric scale is inconvenient. Instead, a convenient way in which the foreshorten-ing of lengths is ignored and actual or true lengths are utilized to obtain the projections, known as isometric drawing, or isometric perspective is normally utilized. This is advantageous because the measurement could be made directly from a drawing. The isometric drawing of the figure is slightly larger (approximately 22%) than the isometric projection. Since the proportions are the same, the increased size doesn’t affect the pictorial value of this representation, and at the same time, it might be done quickly. Shows in below a figure the difference between isometric drawing and isometric projection.  Isometric Drawing Steps to be followed to make an Isometric drawing from orthographic views are given below 1. Study the given views and note the principal dimensions and other features of this object. 2. Draw the isometric axes (a). a- Otrhographic View 3. Mark the principal dimensions to-their true values along the isometric axes (b). b- Isometric View 4. Complete the housing block by drawing lines parallel to the isometric axes and passing Through the above markings (c). c- Isometric View 5. Locate the principal corners of all the features of the object on the three faces of the Housing block (d). d- Isometric View 6. Draw lines parallel to the axes and passing through the above points and obtain the isometric Drawing of this object by darkening the visible edges (e). e- Isometric View Orthographic projection, common method of representing three-dimensional objects, usually by three two-dimensional drawings in each of which the object is viewed along parallel lines that are perpendicular to the plane of the drawing. For example, an orthographic projection of a house typically consists of a top view, or plan, and a front view and one side view (front and side elevations). There are two ways of drawing in orthographic - First Angle and Third Angle. They differ only in the position of the plan, front and side views. Below is an example of First Angle projection. Opposite is a simple L-shape, drawn in three dimensions. The front, side and plan views have drawn around the 3D shape. However this is not the correct way of drawing them as they are not in the right positions. The correct method of presenting the three views, in first angle orthographic projection is shown below. The drawing is composed of a front, side and plan view of the L-shaped object. The first drawing is the front view (drawn looking straight at the front of the L-shape), the second is a drawing of the L-shape seen from the side (known as side view) and last of all a drawing from above known as a plan view. The red lines are faint guidelines and they are drawn to help keep each view in line, level and the same size. NOTE Isometric Drawing An isometric drawing is a type of 3D drawing that is set out using 30-degree angles. It’s a type of axonometric drawing in which the same scale is used for every axis, resulting in a non- distorted image. Isometric View Isometric projection is a method for visually representing three-dimensional objects in two dimensions in technical and engineering drawings. It is an axonometric projection in which the three coordinate axes appear equally foreshortened and the angle between any two of them is 120 degrees.  How Much Have You Learned? SELF-CHECK NO. 1.1 Instruction: Transfer the letters from the isometric drawing on to the same plane surfaces of the orthogonal drawing. Name each view. C B D F E A D E G F C A B  How Do You Apply What You Have Learned? ISOMETRIC DRAWING Instruction: Draw the given isometric drawing on your oslo paper. Follow the given measurements. ACTIVITY SHEET 1.1  ISOMETRIC DRAWING Instruction: Draw the given figure on your oslo paper. ACTIVITY SHEET 1.2  ISOMETRIC DRAWING Instruction: Draw the three regular views of the given isometric drawing in a given grid/box. ACTIVITY SHEET 1.3