Engineering drawing defines requirements for product geometry and manufacturing information.
Orthographic Projection - Multi view drawings showing how the object looks from front, right, left, top, bottom and back positioned according to First Angle & Third Angle projection.
1st Angle: Object --> Image (ISO standard - European)
3rd Angle: Image --> Object (ANSI - USA)
Note: Viewing Direction from Right to Left
I / III Quadrant - 1st & 3rd Angle Projection
II / IV Quadrant - 2nd & 4th Angle Projection valid mathematically but their use will result in one true view and other view flipped by 180 degrees through vertical centreline.
Dimensioning is the process of applying measurements to a technical drawing.
▪ Dimensions - Numerical value expressed in appropriate units of measurement and indicated graphically on technical drawing with lines, symbols and notes. Dimensions can be Functional, Non-Functional, Auxiliary (informative)
▪ Base Dimensioning - from common reference
▪ Parallel Dim / Running Dim / Chain Dim (to be used when there is no accumulation of tolerance)
▪ Feature - Individual characteristics such as flat/ cylinder/ parallel surface, shoulder, screw thread.
▪ End Product - Complete part ready for further processing or assembly/service.
▪ Scale indicates the relative size of the drawing object with the real object.
Type of Views:
▪ Isometric View - View in which the objects vertical line is drawn vertically and horizontal line for width and depth plane are drawn at angle of 30 degrees to horizontal.
▪ Auxillary View - An orthograpic view that is projected on any plane except the six principal views. Used when object features are on inclined plane.
▪ Section View - View of an object from the position of a plane through the object.
▪ Half Section - Showing one half of the view in section.
▪ Broken Section - Passing the cutting plane normal to the object and removing the portion of object in front of it.
▪ Hatching pattern for materials in section views: