Soft Soldering.—Soft solder, so called, is a composition made by melting together two parts tin and one part lead. If the gunsmith ever has occasion to use it, he will need a soldering fluid, which is made by dropping clippings of zinc into muriatic acid until ebullition has ceased, then adding to the acid its equal in bulk of pure water, although some mechanics do not consider the addition of water as necessary.
Clean thoroughly the parts to be soldered together, then wet them with the soldering fluid. Next place in the joint a thin bit of the soft solder, and expose to heat, the heating agent to be clear of oil. The pieces should be held, pressed between the blades of large tweezers, so that when the solder melts the two parts will come directly together. So soon as the solder melts, the work must be taken from the fire, as the soldering will be complete. A little longer exposure would burn the solder and spoil the work.
Good Soft Solder.—Good soft solder is composed of equal parts of pure tin and good soft lead. The lead from old tea-chests is excellent. Plumbers’ solder is often made of lead three parts and tin one part.
Soldering Fluid.—A soldering fluid for jewelers’ use is made by adding to alcohol all the chloride of zinc it will dissolve.
Brazing.—This consists in uniting iron and other hard-melting metals with a brass solder. Put the parts together as for soft soldering, lay the brass between the pieces or along the upper edge of the joint, if it can be held vertically, and add a goodly supply of pulverized borax to act as a flux. Heat over a charcoal fire till the brass melts and runs down into the joint, then take from the fire and cool. Before beginning the operation of brazing the parts to be put together must be made entirely clean, and then freshly filed to brightness.
To Braze Lugs on Gun Barrels.—When not practicable to fasten the lugs by means of pins or rivets, hold them in place with binding wire. Take a piece of iron, say ¼ inch thick and 2 inches or more in width, and make in it a slot some larger than the lug to be brazed. Lay the barrel on the iron sideways, and pack up the lug so as to lie level, if necessary, also taking care that it is on straight. Pure copper is excellent for all kinds of brazing, when the color of the copper is not objectionable.
Hard Soldering.—See “To Solder Brass,” in Chapter XII, which about covers the whole thing, varying only in the composition of the solder for different metals. The brass solder there described acts equally well for soldering copper, but for silver a solder is made composed of two parts silver and one part brass.
Hard Solders.—1. A hard solder that is yellow and easily fusible is made of copper, 4½ parts, and zinc, 5½ parts.
2. To hard solder iron use good tough brass or sheet copper, with borax as a flux.
3. Pure copper, cut in thin strips, with borax as a flux, is excellent for brazing iron or steel.
Alloy for Adhering to Iron or Steel.—Melt together, tin 3 parts, zinc 7½ parts, and copper 39½ parts. Clean the iron or steel, file to brightness and cast the alloy upon it. The iron or steel should be heated up to about the melting temperature of the alloy. This alloy will adhere firmly to the other metal, and as its rate of expansion is about the same as the iron or steel, under all circumstances, it will never come loose. It finishes up nicely and presents a very neat, light yellow appearance. Some gunsmiths use it for brazing purposes on account of its adhesive properties and its ease of fusion. It does not make so strong a joint as brass or copper, and therefore would not give so “honest” a job.
Gun Oil.—A good quality of sperm oil is undoubtedly the best oil to apply to gun work, especially the locks. Any fine animal oil may be used as a substitute. The oil from the fat of the woodchuck or ground-hog is admired by many. Fine quality of sewing-machine oil is very good. It must not be thinned or “cut” with kerosene or benzine, as this reduces its wearing quality. It must not thicken with exposure to the cold.
Vegetable oils are unfit for the locks of guns. Castor oil will gum up and become filthy in the extreme. Olive oil or “sweet oil” has very often been agitated, with common salt, nitric ether, sulphuric acid or hydrochloric acid to keep it from becoming rancid. Application of such oil, in addition to its bad lubricating quality, will rust and spoil work where applied.
If desired to clarify oil, put in a bottle, say a quart of oil, and add about half a pound of fine lead shavings. In a short time the impurities will collect on the lead, when the clarified portion may be poured off. Let the bottle stand in the sun for two or three weeks during the process, and then filter through fine white blotting-paper. If some portion be found to congeal by cold, separate the clear portion from the other, reserving the uncongealed for use during exposure of the gun to cold weather.
Gunsmith’s Glue.—Dissolve four ounces of good glue in sixteen ounces of strong acetic acid by exposure to gentle heat. This is not exactly a liquid glue preparation—it is only semi-liquid. It may be kept for any length of time desired, and, when wanted for use, a slight warming up is all the preparation necessary. The gunsmith finds it not only very convenient, in case he should have occasion to use glue about his woodwork, but also very good.