Engineering Drawing

What is

engineering drawing

An engineering drawing, a type of technical drawing, which is used to fully and clearly define requirements for engineered items with scales.

Engineering drawing example

Artistic

Types of Drawings

All Drawings Technical Sketches (conceptual) ( design Diagram (design plan) Diagrams & technical) Diagram ( technical ) Drawings (technical/engineering) simulated perspective Oblique projection Isometric projection Multi view orthographic

Less technical More technical

Conceptual Sketches

• When any idea comes in your mind, you draw a simple or rough drawing of the object without using any drawing instruments or tolls and this is called a conceptual

sketch.

Importance of Engineering Drawings

• Helps as a reference to workers, technicians or architects.

• Easy to understand : Since a picture is easiest method than thousand words, a technical drawing is a much more effective tool for engineers than a written plan.

• Engineering drawings is used in all engineering fields, including, but not limited to, civil engineering, electrical engineering, mechanical engineering and architecture.

Sketch Vs Engineering drawing

• • Sketch: made without drafting tools... Just pencil and paper. Scale is approximate, not accurate, but the sketch should still look like the object.

Engineering Drawing: Made with drafting tools... Ruler, set squares, protractor and compass. Scale should be accurate and the drawing carefully made.

Projection

• • • If straight lines are drawn from various points on the contour (A contour line is a imaginary line which connects points of equal elevation) of an object to meet a plane, the object is said to be projected on that plane. The figure formed by joining, in correct sequence, the points at which these lines meet the plane, is called the projection of the object. The lines from the object to the plane are called projectors.

Projection

Projection Types

• • Orthographic projection Isometric projection

Orthographic projection

• • • Orthographic Projection is a way of drawing an 3D object from different directions. Usually a front, side and plan view are drawn so that a person looking at the drawing can see all the important sides. Orthographic drawings are useful especially when a design has been developed to a stage whereby it is almost ready to manufacture.

OBJECT

Orthographic projection views

Orthographic projection

• • As shown in the earlier slide, if an observer at position ‘A’ moves to infinity, the projectors to his eyes becomes parallel to the object and he observes the same shape and size as that of the object. The view so formed is known as the orthographic projection.

Similarly, the parallel projectors shall form the pictures on the respective picture planes from the positions B and C.

Isometric Projection

• • Isometric projection is a method for visually representing three-dimensional objects in two dimensions in technical and engineering drawings Isometric drawings consist of two-dimensional drawings that are tilted at some angle to expose other views and give the viewer the illusion that what he or she is viewing is a three-dimensional drawing.

An Isometric Drawing

Comparison of Projections

Orthographic Isometric

Used for : Drafting, maps, floor plans Technical drawings, drafting, conceptual sketches (sometimes) Orthographic is a set of 3 Plane Projections Used for : Conceptual sketches, technical drawings (sometimes) Isometric is a 3-D sketch

Diagrams

• • Diagrams are simplified versions of a drawing. Diagrams show how an object works, not necessarily how it looks.

Diagrams often use symbols rather than actual pictures to represent things.

A Circuit Diagram

– Doesn’t show what the circuit looks like, but tells an electrician how its all connected.