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70. The Rotary Ash Sifter.—This problem on the rotary ash sifter presents a composite of nearly all of the pattern principles that have been given in the preceding problems.

Figure 213 shows a section and Fig. 214 an end elevation of the sifter. Extension lines should be used to establish the elevation positions of the views, but these are omitted from the drawing to avoid confusion of lines.

Pattern of Side (Fig. 215).—A line of stretchout is drawn and upon it is placed the spacing between letters A, K, B, J, C, F, D, and H as shown in Fig. 214. Measuring lines are drawn through each of these points. It should be noticed that points E and D, G and H, M and A fall on the same horizontal lines of Fig. 214. Because of this, they should be similarly placed in the stretchout, Fig. 215. Starting from point A of Fig. 213, an extension line intersecting measuring line A of Fig. 215 should be dropped. In like manner all points of intersection are located. Three-sixteenths inch single edges are added, where shown, to provide for double seaming, and a ⅜-inch edge which is to be bent at right angles to receive the hook of the sliding cover, is allowed for.

Front End of Hopper (Fig. 216).—A line of stretchout is drawn first. Upon this line the distance MK of Fig. 213 is laid off. Measuring lines are drawn through these points. Extension lines from each end of the lines M and K are dropped until they intersect the measuring lines of Fig. 216. These points of intersection are connected by four straight lines to obtain the outline of the pattern. The necessary allowances, as shown, should be added. A notch must be cut out to provide for each hinge strap which is to be folded over the exposed wire and riveted to the cover.

Patterns for the sliding cover, front end of outlet, and bridge are developed by the same method as was the front end of hopper. The spaces KJ, JH, and EFG are taken from correspondingly lettered spaces of Fig. 213. The hook, shown in Fig. 218, is made of 1 in.×⅛ in. band iron.

Pattern for Cover of Barrel (Fig. 220).—The cover is made from one piece of metal, the rim being "flanged" as described in Chapter VII for the treatment of the ash barrel bottom. The width or