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The Question & Answer (Q&A) Knowledge Managenet

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Table of Contents

- When a line is inclined to a plane of projection and parallel to the other plane it will appear in the view?
- What is projection projector and plane projection?
- How do you find true length and true inclination?
- What happens if a line is viewed perpendicular to the plane of projection?
- What are the four standard types of projections?
- What are the 3 principal views?
- What are the 6 principal views?
- Which lines on a drawing should be the thickest?
- What are the principal planes of projection?
- What are the 4 orthographic views?
- Why is front view the principal view?
- What are projection lines?
- What are the two main types of projection?
- What are the different types of projection?
- What is another name for orthographic projection?
- What three sides make an orthographic projection?
- What is the difference between orthographic and perspective projections?
- What is the difference between isometric and orthographic projection?
- Is isometric drawing 2D or 3D?
- What is 3rd Angle Projection?
- Who uses 3rd Angle Projection?
- What is 1st 2nd and 3rd angle projection?
- What is 1st and 3rd angle projection?
- How do you read 1st and 3rd angle drawings?
- Why 3rd angle projection is used?
- Why we use only 1st and 3rd angle projection?
- Why 2nd and 4th angle is not used?
- What is first angle of projection?
- Are the front and right side views aligned vertically or horizontally?

An inclined line is a line in space that is parallel to one of the three principle views. It is neither parallel nor perpendicular to the other two views. The line will appear TL in one view since it is parallel to one of the projection planes. It will appear foreshortened in the remaining two views.

A projection plane, or plane of projection, is a type of view in which graphical projections from an object intersect. With parallel projection the lines of sight from the object to the projection plane are parallel.

Rotating line method The method of obtaining the top and front views of a line, when its true length and true inclinations are given. When a view of a line is parallel to the XY line, its other view will be in true length and at true inclination.

If the observer views the surface such that the lines of sight are perpendicular to the plane, he or she will see the plane in its true size and shape. This will hold true if the plane surface is projected onto a projection plane parallel to it.

Overview

- Multiview projection (elevation)
- Axonometric projection (isometric)
- Oblique projection (military)
- Oblique projection (cabinet)
- One-point perspective.
- Two-point perspective.
- Three-point perspective.

The standard views used in a three-view drawing are the top, front and the right side views Page 16 The width dimensions are aligned between the front and top views, using vertical projection projection lines.

What are the six principal views of an object? Front, top, right side, left side, rear, and bottom.

The direction of the cutting line is shown with a line called a cutting plane lineHeavy dashed line that shows a theoretical cut through an object.. This is the thickest line that may appear on a drawing. It is made up of a series of 3/4″ long (19mm) and double lines 1/8″ (3.2mm) long that are about 0.040″ (1mm) thick.

Principal Plan Views. The six orthographic views projected onto the sides of an imaginary “glass box” surrounding a subject using orthographic projection. These are the top, bottom, front, rear, left, and right views. All six principal plan views are normal views.

An orthographic projection is a way of representing a 3D object by using several 2D views of the object. Orthographic drawings are also known as multiviews. The most commonly used views are top, front, and right side.

In multiview projection, the object is viewed perpendicular to the main faces, so that only one face of the object is depicted in each view. Main principles of creating multiview projections: The most informative (descriptive) view of the object to be represented is normally chosen as the principle view (front view).

Projection lines are extensions of lines that assist in 2D drawing. For example, in a drawing, you can use projection lines on an auxiliary view to enable creation of additional views with proper alignment and size.

The most common types are the perspective and orthographic projections.

Types of Projection. The Center of Projection

- 2.1 Central (conical) Projection.
- 2.2 Parallel (cylindrical) Projection.
- 2.3 Properties of the Central (conic) Projection.
- 2.4 Properties of Parallel (cylindrical) Oblique-Angled Projection.
- 2.5 Properties of Parallel Rectangular (orthogonal) Projection.

orthogonal projection

Three sides are normally used to make orthographic projections – Front View, Top View and Right Side View.

In the perspective view (the default), objects which are far away are smaller than those nearby. In the orthographic view, all objects appear at the same scale. Perspective viewpoints give more information about depth and are often easier to view because you use perspective views in real life.

Isometric: a method of representing three-dimensional objects on a flat surface by means of a drawing that shows three planes of the object. Orthographic: a method for representing a three-dimensional object by means of several views from various planes.

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.

3rd Angle project is where the 3D object is seen to be in the 3rd quadrant. It is positioned below and behind the viewing planes, the planes are transparent, and each view is pulled onto the plane closest to it. The front plane of projection is seen to be between the observer and the object.

Orthographic Representation Third angle projection (figure 1.2) is used mainly in The United States and Canada whilst first angle projection (figure 1.1) is used mainly throughout Europe and the rest of the world.

To get the first angle projection, the object is placed in the first quadrant meaning it’s placed between the plane of projection and the observer. For the third angle projection, the object is placed below and behind the viewing planes meaning the plane of projection is between the observer and the object.

The object is placed in the first quadrant. The object is placed in the third quadrant. 2. The object is placed between the plane of projection and observer. The plane of projection is placed between the object and observer.

The difference between first and third angle projection is in the position of the plan, front and side views. In third angle, what you see from the right would be drawn on the right. In first angle, the view from the right would be projected through and drawn on the left.

When using third angle projection to compile a diagram of the three views, we first draw the most prevalent side of the object as the front view. The top view is positioned directly above the front view and for the side view, we generally position the right side view on the right of the front view.

Europe had used the method of first angle projection in creating orthographic views of three-dimensional parts for manufacturing for many decades, while in the U.S., engineers had settled on using third angle projection with its more logical placement of views.

Overlapping projection views create confusion in the drawing. Therefore the 2nd angle projection system is not used to draw engineering drawings. Similarly when the object is placed in the 4th quadrant both top and front view will overlap. Therefore fourth angle projection is also not used.

First-angle projection: In this type of projection, the object is imagined to be in the first quadrant. Because the observer normally looks from the right side of the quadrant to obtain the front view, the objects will come in between the observer and the plane of projection.

13 Cards in this Set

An orthographic projection is a ___ representation of an object | 2-D |
---|---|

The view that generally contains the least number of hidden lines | Front |

How are the front and right side views aligned? | Aligned horizontally |

How are the front and top views aligned? | Aligned vertically |