The parts necessary for making an electric stove are: Two metal pie plates of the same size; 4 lb. of fire clay; two ordinary binding posts; about 1 lb. of mineral wool, or, if this cannot be obtained, thick sheet asbestos; one oblong piece of wood, 1 in. thick, 12 in. wide and 15 in. long; one small switch; one fuse block; about 80 ft. of No. 22 gauge resistance wire, German-silver wire is better, as it stands a higher temperature; two middle-sized stove bolts with nuts; one glass tube, about 1/4 in. in diameter and 9 in. long, which can be bought from a local druggist, and two large 3-in. screws.
If a neat appearance is desired, the wood can be thoroughly sandpapered on one side and the corners and edges rounded off on the upper side. Punch holes in one of the pie plates, as shown in Fig. 1. The two holes, E and F, are on the rim and should be exactly on a line with the hole D punched in the center. The holes B and C are about 3 in. apart and should be at equal distances from the center hole D. The rim of the second plate is drilled to make two holes, AA, Fig. 2, that will match the holes E and F in the first plate, Fig. 1. A round collar of galvanized iron, FF, Fig. 4, 3 in. high, is made with a diameter to receive the first plate snugly. Two small flaps are cut and turned out and holes punched in their centers, AA, to receive screws for holding it to the base. Two bolts are soldered in the holes E and F, Fig. 1, and used to hold the rims of both plates together, when they are placed in opposite positions, as shown in Fig. 4. This will make an open space between the plates. The collar is then screwed to one end of the base, as shown in Fig. 2.
Illustration: Details of Electric Stove
Two holes are bored through the base to correspond with the holes D and A in the bottom plate. The glass tube is cut to make two pieces, each 4-1/2 in. long. This can be done easily by filing a nick in the tube at the proper point and breaking it. These tubes are forced into the holes bored in the base, and, if the measurements are correct, should extend about 1/4 in. above the collar. The mineral wool, JJ, Fig. 4, is then packed down inside the collar, until it is within 1 in. of the top. This will allow the plate, Fig. 1, to rest on the wool and the ends of the glass tubes, GG, Fig. 4, to project through the holes D and A of the plate, Fig. 1. The rim of the plate should be level with the top edge of the collar. If asbestos is used, the sheets should be cut into disks having the same diameter as the inside of the collar, and holes cut to coincide with the holes D and A of the plate. The small scraps should be dampened and made into pulp to fill the space H, Fig. 4. The plate, Fig. 1, is held to the base by two screws which are run through the holes BC and take the position shown by DD, Fig. 4.
The two binding-posts are attached on the base at D, Fig. 2, also the switch B and the fuse block C, holes being bored in the base to make the wire connections. The reverse side of the base, with slits cut for the wires, is shown in Fig. 3. The points marked BB are the glass tubes; AA, the holes leading to the switch; and C, the fuse block. The wires run through the glass tubes GG, Fig. 4, are allowed to project about 1 in. for connections.
The best way to find the correct length of the resistance wire is to take a large clay or drain tile and wind the wire tightly around it, allowing a space between each turn. The tile is then set on its side with a block or brick under each end. It should not be set on end, as the turns of the wires, when heated, will slip and come in contact with each other, causing a short circuit. When the tile is in place, a short piece of fuse wire is fastened to each of its two ends. A 5-ampere fuse wire is about strong enough. A connection is made to these two wires from an electric-light socket. The wire will get hot but probably remain the same color. If this is the case, one of the feed wires is disconnected from the fuse wire and gradually moved farther down the coil until a point is found where the resistance wire glows a dull red. This point marks the proper length to cut it, as the wire should not be allowed to become any hotter. If the wire gets bright hot when the current is turned on, more wire should be added. The wire is then made into a long coil by winding it around a large wire nail. The coils should be open and about 1/8 in. apart.
Next, the fire clay is moistened and well mixed, using care not to get it too wet. It should have the proper consistency to mould well. The clay, II, Fig. 4, is then packed in the first plate to a height of about 1/4 in. above the rim. While the clay is damp, one end of the coil is connected with the wire in the central glass tube, and the coil laid in a spiral winding on the damp clay, KK, and pressed into it. When this is done, the other end is connected to the wire projecting from the outer glass tube. As these connections cannot be soldered, the ends of the wires should be twisted closely together, so that the circuit will not become broken. Make sure that the coils of wire do not touch each other or the top plate. The fuse wire (about 5 amperes) is put into the fuse block, and wires with a socket adapter connected to the two binding-posts. The top plate is put in place and screwed down. This completes the stove.
It should be set aside in a warm place for a few days to dry out the packing. If it is not thoroughly dry, steam will form when the current is applied. It should not be left heated in this condition. The top plate is used when cooking and removed when making toast. --Contributed by R. H. Cnonyn, St. Catherines, Can.