PROJECTION DRAWING

An important part of drawing work is the representation of the exact shaрe and size of a solid object. The solid which has length, breadth and thickness (three dimensional) is regarded as two dimensional on the surface of a drawing sheet.

State Standard 2.305-68 sets the rules of object depictions (wares, buildings and their component parts) on the drawings of all branches of industry.

The number of depictions of an object must be minimum but sufficient for determination of its form and forms all its elements.

The method of rectangular projection is used for the depictions, when an object is placed between the eye of the observer and the plane of projections. The basic planes of projections are chosen six verges of hollow cube, in the middle of which an object is placed which is projected on the internal verges of the cube. Then the basic planes of projections are combined with a frontal plane which result in a complex picture (fig.2.1).

Figure 2.1– The basic planes of projections

A depiction on the frontal plane of projections is considered to be the main. An object is placed in relation to the frontal plane of projections so that a representation on it (the main depiction) gives the most complete picture of form and sizes of an object.

The depictions are divided into views, sectional views and sections according to a State Standard 2.305-68 standard .