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33. The Tangent Tee at Right Angles.—When a straight line and the circumference of a circle touch each other at but one point, the straight line is said to be tangent to the circle. Their point of meeting is called the point of tangency. A straight line from the center of the circle, meeting the tangent at an angle of 90°, locates the point of tangency. In Fig. 101, the tangent and the point of tangency are plainly indicated.

Tangent Tee.—When the tee joint is so placed upon the main pipe that one side of the tee is tangent to one side of the main, as in Fig. 100, the fitting is known as a "Tangent Tee." The use of this type of fitting enables the designer to keep the distance from the ceiling to the top of every horizontal pipe uniform throughout the entire system. All hangers for the piping can be made the same length and the entire job will have a neater and more workmanlike appearance.

Side Elevation.—A side elevation should be drawn according to the dimensions given in Fig. 101. After drawing a profile, it should be divided into sixteen equal spaces, and extension lines from each division carried to the apparent miter line. The divisions of the profile should be numbered, and the intersections of the apparent miter line lettered as shown in Fig. 101.

Front Elevation.—The front elevation can be located by extension lines. Another profile should be drawn above the front elevation. It must be divided into the same number of equal spaces as the profile of Fig. 101. It is to be numbered, placing number 1 on the left-hand side. Extension lines are dropped from each division of the profile, Fig. 102. Other extension lines are carried over from the intersections of the apparent miter line. Fig. 101, until they intersect the extension lines drawn from the profile. Starting from point 1 in profile of Fig. 101, the extension line should be traced downward to the apparent miter line, and thence to a correspondingly numbered line dropped from the profile of Fig. 102. In like manner, ah the divisions of the profile, Fig. 101, can be traced and each intersection marked with a small circle as shown in Fig. 102. A curved line passing through these points will give the developed miter line.