Page:Sheet Metal Drafting.djvu/35

Rh 15. The Iron Bread Pan.—The particular feature of the construction of this bread pan is the method of joining the body to the end by double seams.

The bread pan, Fig. 31, is to be made of No. 28 black iron. It is to be wired with No. 8 wire and the ends are to be double seamed in. Figure 36 shows that this double seaming is accomplished by turning a hook on the body and a right-angled bend on the end. After being slipped together, these edges are hammered down to form the double seam. The Double Edge is the trade name for the hook that is turned on the body. The Single Edge is the trade name given to the right-angled bend on the end. Allowance must be made for the metal necessary to make these bends. This allowance is called the "Take-up" and is indicated in Fig. 36.

The end elevation is drawn first and the points of the profile numbered 1, 2, 3, and 4 as shown in Fig. 32. The front elevation can be located by using the extension lines from the end elevation. The line of stretchout is drawn at right angles to the bottom of the pan. The spacing of the profile and the corresponding numbers are then transferred to the line of stretchout. This pan is to be wired around the top with a No. 8 wire which is in. in diameter. After this allowance for wiring is computed, this distance must be added to the line of stretchout outside of points 1 and 4. After the measuring lines are drawn on the pattern, extension lines are dropped from the front elevation into the stretchout. These will locate the extreme points of the top and the bottom and permit the drawing of the outline of the body pattern as shown in Fig. 34. Three-eighths inch double edges are added as shown. The bending lines of the double edges are drawn ⅛ in. in from the outside edge. This allows in. for take-up.

The pattern of the end is constructed by dropping extension lines from the end elevation and by carrying extension lines over from the upper surface of the body pattern. The intersections of these extension lines will locate the corners of the end pattern as in Fig. 35. Three-sixteenths inch edges are added on the three