Page:Sheet Metal Drafting.djvu/164

150 Pattern of Pump Barrel (Fig. 201).—The pump barrel blank is a rectangular piece of metal whose length is 19⅝ in. (⅛ in. being added for joining to the nozzle), and whose width is (1¾ in.×π)+½ in. for locks. A pattern of the pump barrel should be drawn as shown in Fig. 201, The ⅛-inch screw holes should be equally spaced with the circumference of the barrel, the outside holes being of the circumference distant from the circumference lines, in order to bring the seam in the center. A -inch hole must be provided, as shown, for a vent.

Pump Rod Details(Fig. 202).—The pump rod should be 21½ in. long and should have a stop washer soldered 3½ in. from one end. This stop washer prevents the leather packing from becoming injured by striking the nozzle. A ¼-inch standard stove bolt thread (18 threads per inch) is cut on each end of the rod for a distance of ½ in. The thread near the stop washer is intended to screw into wooden handle. Two iron washers of unequal diameter are drilled and tapped to receive the thread that is cut on the pump rod. The cup leather is clamped between these washers, the larger washer being on the side near the handle of the pump.

Pattern for Reservoir (Fig. 203).—The pattern for the body of the reservoir is a rectangle whose length equals (4×π)+½ in. for locks, and whose width equals 5 in. A center line is drawn and the -inch hole for the tube is located upon it. A hole for the ¾-inch screw can top is also located as shown in Fig. 203. The pattern for the ends of the reservoir is a circle 4 in. in diameter to which is added a ⅛-inch burr to act as a lap for soldering the ends to the body. The brace is a rectangular piece of tin ¾ in. wide. The length of the brace is taken directly from the profile as it appears in Fig. 199.

Schedule of Materials.—When making a drawing of an article that has many parts, a schedule of material is included in the drawing. This schedule saves a large amount of description regarding material, etc., that would otherwise have to appear on the drawing for each part, thereby complicating the drawing and making it more difficult to read.

67. Related Mathematics on Atomizing Sprayer.—In planning an article that is to be manufactured the draftsman must constantly strive to keep the cost as low as possible. The largest items entering into the cost are material and labor. The various parts must be so designed that they will "cut to advantage" from