Lesson 1: Drafting Equipment – Tools And Materials
T – Square
A T – Square (fig. 5) is a free sliding instrument that moves up and down on a drafting board. It is a device that resembles letter for which it was named. The drafter keeps it parallel by keeping the “T” end flush against one of the edges of the board. It establishes a horizontal base for drawing lines or for orienting other equipment like triangles when drawing vertical and inclined lines. It is also a useful instrument for drawing extremely long lines that deviate from the horizontal plane. It is also used for locating reference points. It can also be used for guiding an affixed triangle used for drawing vertical lines. A T-Square consists of two parts, the head and the blade or straight edge. The head is fixed solidly to the blade. Some are also available with protractor head and adjustable blade. Clear plastic strips inserted in the blade edges make it easier to locate reference points and lines.
Fig. 5 T – Square
Common T-square lengths for use in architectural drafting are 18 “, 24 “, 30 “, 36 “and 42 “. For accurate line work the head should be held firmly against the working edge of the board and triangles must be held firmly against the blade. If the blade is not held firmly on the board it may sag and not give straight lines.
Use: To draw Horizontal Lines the head of the T-square is held firmly against the working edge of the drawing board which ensures the blade in a horizontal position to draw horizontal lines from left to right or right to left as the case may be. (fig.6)
Triangles are used with the T-Square to draw vertical or inclined lines. The 10”, 30º x 60º triangles are preferred for architectural work.
Fig.6T – Square in use
Care: A T-square must never be used as a guide or a knife or any other cutting tool the blade must be left flat on the board or stored suspended from the hole in its end to keep warping or bowing of the blade to a minimum.
Participants