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��1^2 in. outside diameter. This piece will be long enough to give the ports and intake as well as the steam- chest. Cut a piece 8 ins. long for the steam-chest. Square up both ends with a file and remove all burrs from the inside end with the point of a knife- blade. Next measure in from each end of the pipe ] 2 in. and drill a }/i-m. hole at each of these points for the ports. Be sure to drill the holes on the same side of the pipe.
The ports P shown in Plate 2 are made from the piece of tubing left from the steam-chest by cutting two pieces each ^4 in. long. File one end of each to fit the steam-chest tube and the other end to fit the cylinder tubing. Solder these pieces to the steam-chest over the holes drilled for the ports. A }-i-in. hole is next drilled }i in. from the cylinder heads in each of the cylinders, after which they are temporarily fast- ened in position on the cylinder support with these holes on top. Next solder the other end of the port pipes to the cylinders. Remove all burrs from the inside of the steam-chest and cylinders with file, emery-paper or knife-blade.
The slide valve-rod is made from a piece of H in. brass rod 9 ins. long. It is first bent to the shape and flattened on the end as shown, SVR in Plate 2. Next file two notches around the rod. These are about >4 in. wide and not quite 1/16 in. deep. The cen- ter of the first one is located 1)4 ins. from the center of the 3/16-in. hole, which is drilled
in the flattened end for the bolt. The center of the other one is made exactly 7 ins. from the first one. Be careful to get these properly located as it is the most important pari <A the engine.
The slide valves are cast on the slide valve-rod just described. Use babbitt
���Plate 2. Construction details of the slide valves
��metal for this. A piece of the 3^-in. tubing ^8 in. long is first worked out and all burrs removed from the inside. A H-in. hole is bored in a board ^8 inch. deep. In the center of this hole the M-in. bit is placed and the hole bored on through the board. Now place the small piece of pipe in the J^^-in. hole and slip the vaK^e-rod into the },<i-m. hole, passing it down until the first notch is in the center of the pipe. The valve may be cast by running the pipe full of babbitt. Carefully remove from the mold and set it up for the other valve, using the same piece of pipe. When both valves are cast in place they are carefully fitted into position in the steam-chest. If they are found to fit too tight they may be scraped very lightly with a knife.
From the piece of i32-'n. pipe left from the cylinders make the eccentric ring. This is made just }/2 in. wide. After it has been carefully worked into form and the edges rounded a trifle on the inside as well as out it must be used to cast the eccentric and piston-heads.
The small piece of pipe is then fitted and soldered to it, as shown in Plate 3.
The purpose of the eccentric is to throw the valves first to one side of the ports and then to the other. The eccentric mold shown in Plate 3 is used to produce the casting for the eccentric. In making the mold the expansive bit is used to bore a hole }y in. deep in a block of wood. This hole should per- mit the eccen- tric ring to come into it evenly. After this hole has been smoothed the 3^8-in. hole men- tioned above is Ijored as well as of the center for
��one on the other side pouring the metal.
Prepare the mold for pouring by installing the brass ring. After turning the o]>en face of the mold down on a piece of paper laid on the bench and sciuaring up the piece of ^ in. steel, the mold may be poured.