Week 9:- 2D Detailing Challenge
1.Drawing templates:A drawing template stores document settings that you can use again and again. This can include a sheet format. Here are some examples of these settings:
- Drawing Document Properties: Drafting Standards, Units, Font style and sizes, etc.
- Custom Properties
- Tree Display
- Predefined Views
2.Angle of Projection:The angle at which an observer draw an object to convert it from 3D to 2D plane such as real object image to a plane paper is known as angle of projection. There are two angle of projection used in drawing:
- 1st angle of projection(first quadrant of coordinate plane)
- 3rd angle of projection(3rd quadrant of coordinate plane)
3.
The orthographic projection system is used to represent a 3D object in a 2D plane. The orthographic projection system utilizes parallel lines, to project 3D object views onto a 2D plane. According to the rule of orthographic projection. To draw a projection view of a 3D object on a 2D Plane. The horizontal plane is rotated in the clockwise direction.
Types of Orthographic projection systems are first angle and third angle projection.
1. First Angle Projection :
In the first angle projection, the object is placed in the 1st quadrant. The object is positioned at the front of a vertical plane and top of the horizontal plane. First angle projection is widely used in India and European countries. The object is placed between the observer and projection planes. The plane of projection is taken solid in 1st angle projection.
Symbol –
2. Third Angle Projection :
In the third angle projection, the object is placed in the third quadrant. The object is placed behind the vertical planes and bottom of the horizontal plane. Third angle projection is widely used in the United States. The projection planes come between the object and observer. The plane of projection is taken as transparent in 3rd angle projection.
Symbol –
Difference between First Angle Projection and Third Angle Projection:
| SR.NO | FIRST ANGLE PROJECTION | THIRD ANGLE PROJECTION |
|---|---|---|
| 1 | 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. |
| 3 | The plane of projection is opaque. | The plane of projection is transparent. |
| 4 | Front view is at the top of the horizontal axis. | Front view at the bottom of the horizontal axis. |
| 5 | Top view at the bottom of the horizontal axis. | Top view at the top of horizontal axis. |
| 6 | Right view is at the left side of vertical axis. | Right view is at the right side of vertical axis. |
| 7 | Left view is at the right side of vertical axis. | Left view is at the left side of vertical axis. |
| 8 | It is widely used in Europe, India, Canada. | It is widely used in United State and Australia. |
why we wont use 2nd Angle & 4th Angle projection:
Let us consider a cylindrical cone in placed vertically in the first quadrant:
Consider Horizontal Plane as rotating medium,Rotate Horizontal Plane by 90 degrees
Projections of this will give the symbol of First Angle Projection
Let us Consider the cone placed vertically in the 3rd Quadrant 
Consider Horizontal Plane as a medium and rotate it by 90 degrees.Projections will gie the symbol for 3rd Angle Proection.
Let us consider the cone placed in 2nd quadrant
If we rotate the horizontal plane The projections will overlap.
That is why we dont use 2nd angle and 3rd angle projections.
4.GD&T:Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describe nominal geometry and its allowable variation.
Benefits of GD&T:
GD&T, a vital part of complex machining, offers a number of major advantages:
- Saving Money — GD&T enhances design accuracy by allowing for appropriate tolerances that maximize production. For many projects, the process provides extra or bonus tolerances, further increasing cost effectiveness.
- Ensuring Dimensional and Tolerance Requirements — By explicitly stating all design requirements, a thorough GD&T process guarantees accurate fulfillment of all dimensional and tolerance specifications.
- Assisting Digital Design Methods — Clear, concise GD&T data is readily adaptable to digital design programs, including nearly universally used 2D and 3D CAD files.
- Offering Uniformity and Convenience — As a single, consistent language, GD&T reduces guesswork and interpretation while ensuring consistent geometries across design and manufacturing.
- Providing Accurate Communication — Today’s intricate designs demand the most accurate and reliable communication. GD&T enables designers, manufacturers, and inspectors to communicate clearly with one other, saving time and making the process more efficient.
5.Symbols used in GD&T: