Important: Safety Warning
This page describes practices involving highly flammable materials in ways that create a serious risk of fire or explosion.
In addition, this page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Soldering Pads
Figs. 290 to 292 illustrate Melotte's non-conducting soldering pads, which are reversible, and adapted to contain a small crucible and ingot mould on one side, a removable rim, shown in Fig. 290; a detachable handle, and various spring clamps as shown. Fig. 292 illustrates Melotte's new gas blow-pipe, which is used with these pads. This blow-pipe is simple and convenient, and, as will be seen by consulting the illustration, it consists of a blow-pipe of the ordinary form having a gas pipe inserted in the lower half, and a threaded hood or sleeve at the lower end, which changes the shape of the flame by screwing in or out, so as to vary the influence of the current of air upon the flame. A ring adapted to slip over the finger while working, is soldered to the middle joint of the pipe, and the quantity of gas is controlled by the stop-cock and spring lever shown in the cut, the gas being supplied to the pipe by a rubber tube connecting it to the nearest gas jet in the usual way. Thus having the shape of the flame under control, and the quantity variable at will, the workman is in position to accomplish the desired end speedily and effectually.
To use to the best advantage, set the jamb-nut so that with the valve lever in its normal position, the flame at the end of the pipe will just keep alight. The blow-pipe can then be laid down temporarily, and again used without the trouble of turning off the gas or relighting.
When used as a mouth blow-pipe, the most convenient way to hold it is with the third finger through the ring. For bellows work it is better to pass the ring over the index finger. The ring also serves, with the valve-lever, as a rest to hold the flame-nozzle away from the table when the blow-pipe is laid down temporarily.
To produce an oxy-hydrogen flame, connect the air-pipe with a cylinder of nitrous oxide, opening the cylinder-valve carefully, so as to permit the escape of only sufficient nitrous oxide to produce, with the illuminating gas, a very small flame. Regulate the illuminating gas flow with the thumb-screw, or with the finger on the lever of the blow-pipe valve. For soldering, use the grooved face of the pad, with or without the removable rim (shown in Fig. 290), according to the work. The wire staples answer the double purpose of holding the removable rim in place and raising the pad from the table, with air-space underneath.
The spring-clamps are useful in holding the parts to be soldered, the loops in the metal band around the pad permitting them to be placed in any desired position.
For melting, use the reverse side of the pad, with the depression for melting-cup. Fig. 293 shows the melting-cup and ingot-mould in place. The shield is a flat piece of metal, with a lip at one end. The small melting-cups should always be used, as flux adheres to the pad, and pulls off particles of the fiber. The cup is held in place by two pins, inserted in the pad on either side, with the head bent over the edge of the cup. Place the shield upon the pad, with the lip in the depression underneath the edge of the cup; and fasten securely by placing pins through the notches in the edges. Then place the ingot-mold upon the shield, with the mouth of the proper matrix opposite the lip in the cup. To insure a smooth ingot, the ingot-mold should be slightly warmed, and oiled or waxed. After the metal is melted, tilt the pad gradually, carrying the metal toward the mold, and pour quickly. The handle of the pad can be attached at any point.