Page:Sheet Metal Drafting.djvu/169

Pattern of Bottom of Pan.—The profile of the bottom, Fig. 210, of the pan as shown in Fig. 206 should be reproduced, and a ⅜-inch double edge added to all sides of this profile in order to double seam the bottom of the pan to the sides and ends.

The Bail.—The bail is made from galvanized ¼-inch rod, and is attached to the pan by bail ears. The bail ears are located "off center" to assure steadiness when carrying the pan. Figure 207 gives the location of the bail ears. An elevation of the bail, as shown by Fig. 212, is drawn. If care is taken to give center line measurements, the workman in the shop can "scale" his dimensions directly and, therefore, a pattern for the blank will not be needed.

69. Related Mathematics on Ash Pan.—Problem 36A.—What is the area of Fig. 208?

In solving this problem use the formula ${\frac {B+b}{2}}\times H={\text{Area}}$

${\begin{aligned}B&={\text{length of longest arc}}\\b&={\text{length of shortest arc}}\\H&={\text{length of ``line a''}}\end{aligned}}$

Problem 36B.—What is the total area of the sides (two wanted) as shown in Fig. 209?

Use the formula ${\frac {B+b}{2}}\times H={\text{Area}}$
in which

${\begin{aligned}B&={\text{lower base (over-all dimensions)}}\\b&={\text{upper base (over-all dimensions)}}\\H&={\text{total height between bases}}\end{aligned}}$

Problem 36C.—What is the total area of Fig. 211?

Problem 36D.—What is the area of Fig. 210? Figure 210 is a combination of a rectangle and a semicircle.

Problem 36E.—How long must the wire be to stiffen the top edge of the pan? How much rod is needed to make the bail?

Problem 36F.—Number 24 gage black steel weighs 1.02 lb. per square foot. How much will the pan weigh exclusive of the bail and the top wire?