Page:Sheet Metal Drafting.djvu/127

Rh The Profile.—The profile of the body should be drawn. The profile of the hoops would be larger than that of the body, but since the pattern for the body and the location of the slats are to be obtained, the profile of the body must be dealt with. This profile is divided into eight equal parts. Fig. 155. Using any two divisions of the profile as centers, the two slats are drawn in their proper positions. The profile. Fig. 155, shows the three-rib slat, but a single-rib slat may be drawn in. A straightedge laid across the slats, in the manner shown in Fig. 155, should clear the body of the barrel; otherwise, the slats will not protect the body when in contact with the edge of the ash cart. If the straightedge touches the profile, the slats must be made larger or spaced more closely together.

Pattern for the Body.—A line of stretchout, Fig. 159, should be drawn and the spacing of the profile transferred to it, with numbers to correspond. Measuring lines are drawn through each division of the stretchout. One-half inch locks are set off on each end of the pattern. The top and bottom lines of the pattern are drawn 24 in. apart. A distance of $$\scriptstyle\frac{7}{16}$$ in. should be measured in from the top and the bottom lines. These lines will serve as center lines for the rivet holes of the hoops and slats. From Fig. 158 the distance from center to center of the ½-inch edge of the single-rib slat is found to be 1⅜ in. This will also be the distance between centers for rivet holes in the body. One-half of this distance $$\scriptstyle\frac{11}{16}$$ in., is placed on each side of every measuring line in the stretchout. It should be indicated on the drawing that these are to be punched for 2½ lb. rivets. Another line running horizontally through the center of the pattern should bear the same spacing for riveting the center of each slat. The rivet holes for the upper and lower hoops are located midway between measuring lines 1 and 8, 7 and 6, 5 and 4, 3 and 2 as shown in Fig. 159. This allows for four rivets. Therefore, the distance between centers for each pair of rivets will be one-fourth of the circumference. In order to avoid riveting through the seam, the first hole is spaced $$\scriptstyle\frac{1}{16}$$ of the circumference, and the last hole $$\scriptstyle\frac{3}{16}$$ of the circumference away from the circumference line No. 1 of the stretchout. The rivet holes for the drop handles should be placed at ⅔ of the height of the barrel as shown. Fig. 157.

Upper and Lower Hoops.—The upper hoop must be fitted inside of the body. In order for the hoop to go inside, some allowance