Common Principles of Orthographic Drawing:

The following principles must be thoroughly understood before any attempt is created to prepare an orthographic drawing

(a)The elevation and plan are usually in a vertical line.

(b)The side elevation and elevation are usually in a line horizontally.

(c)The length of the plan horizontally is usually the similar as the length of the elevation horizontally.

(d)The height of the side elevation is usually the similar as the height of the elevation.

(e)If a line is parallel to a plane of projection, after that it will display its true length on the same plane.

(f)If a line is inclined to a plane of projection, then projection on the similar plane will be a line shorter than the length of line or true length. The projected length will be a function of the angle of the given line along with the plane.

(g)If a line is perpendicular to a plane, after that its projection on the similar plane will be a point.

(h)If a thin surface or plane is parallel to a plane, after that its projection on the similar plane will show its true shape and size.

(i) If a surface or plane is inclined to a reference plane, after that the projection of the surface on such plane will be foreshortened or will not be true shape.

 (j) If a thin surface is perpendicular to a plane, after that its projection on the similar plane will be a straight line.