With the blocks bored, put a keen edge upon your jack-knife blade, preparatory to Shaping the Outside of the Gun. Figures 311 and 312 show the diameters to which the blocks should be cut. Shape down the small end of each block first, then work back to the other end. At the muzzle end of the block A, make the wood around the bore as thin as you can cut it without cutting through, and from that point taper the wood up to the other end. Round off the breech end of block B, and taper off the other end, as shown.
After cutting, sandpaper the surfaces of both pieces of the tube until absolutely smooth, and see that the end of piece A fits snugly into the hole in the end of B; these sections are to be glued together later.
The Plunger (C, Fig. 308) may be either a piece of a dowel-stick, or a stick whittled round, of the size shown in Fig. 313. Drill a small hole through the plunger stick 1 1/2 inches from one end, slip a piece of spring-brass wire through the hole, and wind the wire loosely around the stick to about the point shown, to form a spiral spring. Slip the end of the plunger into section B of the gun, and out through the hole in the breech. Saw off the end of a spool (D, Fig. 314), glue it upon the end of the plunger (Fig. 308), and drive a small brad through the spool end into the plunger end, to reinforce the connection.
Test the Gun to see that the spring rebounds properly after its compression, before you glue sections A and B together. Figure 315 shows a detail of the
Three-Eighths Inch Shells. These can be sawed up quickly, to the given length, if you will cut them from a 3/8-inch dowel-stick. Taper one end of each shell to a point, as shown, and sandpaper smooth. To make the shells discharge from the gun with a minimum amount of friction, wax them and wax the bore of the gun.
If you find that the spring does not recoil satisfactorily, try a smaller or larger gauge of brass wire. Provided you use spring-brass wire, you should have no trouble with the coil. Space the turns of the coil about as shown in Fig. 313. With the spring properly adjusted, glue together the two sections of the gun tube, and the gun will be ready for mounting on
The Gun-Carriage. Figure 316 shows a rear elevation of the mounted gun, and Fig. 317 shows a detail of the carriage framework. The pair of carriages F may be prepared in one piece, cut out of a piece of wood 5/8 inch thick, then sawed in half. Figure 318 shows a dimensioned pattern for marking out the piece. The 1/4-inch hole is for the wheel axle; the 1/8-inch hole is for the trunnion screws on which the gun is to be mounted. Separator block G (Fig. 317) braces the trail of the carriage. Make it of the size shown in Fig. 319. Before fastening carriages F to G,
Fig. 316. - Rear Elevation of Mounted Gun Fig. 320. -Wheels FIG. 317. - Detail of Gun Carriage Fig. 321. - Spool Wheel Hub
FIG. 318. - Pattern for Carriages Fig. 322. - Wheel Axle
FIG. 319. - Carriage Separator Block Fig. 323. - Bed Block for Gun cut wheel axle K (Fig. 322), and slip it into the holes bored for it. to keep the holes opposite one another while you nail the pieces together.
The Gun-Carriage Wheels I may be prepared in one pie hen sawed in half. Figure 32c shows the pattern. The best way to cut a wheel is to saw out the pieces roughly. first then trim up to the finish line with a sharp chisel, and sandpaper the edge smooth. The wheel hubs are spool ends J. Fig. 321). Fasten them to the wheels with glue. Drive brads through the axle ends for pins to keep the wheels from coming off.
Mounting the Gun. Because of the thinness of the tube of the gun. the screw trunnions cannot be driven into it. The gun must be mounted upon a bed block (E. Figs. 316 and 323), and the trunnions screwed into the block's sides. The upper side of block E must be curved the same as the surface of the gun. To get the right curve, bore a 1-inch hole through a block, then cut this block through at the center of the hole, and trim it up to the dimensions shown in the diagram of Fig. 323. Glue the gun to the bed block.
and when the glue has set drive a small screw through each carriage into it.
The Elevating Device of this home-made gun is simple. Drive four brads into the top edge of each carriage Fig. 317), and cut the cross-bar H to slip between the brads. The bar can be adjusted to four positions.
The Siege Gun shown in Fig. 306 is made in much the same way as the held artillery gun just described. In the detail of the completed gun (Fig. 324), the dotted lines indicate two of the positions to which the gun can be elevated. The carriage is pivoted like a turntable to provide for shifting the position laterally.
Figure 325 shows a longitudinal section of the gun. The tube is made of two pieces (A and B), and Figs. 326 and 327 show the dimensions of the blocks out of which to cut them. Bore a 5/8-inch hole through the center of block A, from end to end, and a hole of the same size through all but 1/4 inch of the length of block B; then with a 1/4-inch bit bore a hole through the remaining 3/4-inch of the length of block B (Fig. 327). Care must be taken to bore the holes absolutely straight, else the bore of the gun will not be straight, and the toy shells will lose momentum before leaving the muzzle of the gun.