Mainsprings.—Mainsprings are made for right and left side locks, and are known as right and left. Very few gunsmiths make these springs, as they are kept in stock and can be purchased of the dealers at any time. Fig. 54 is called the forward or side-action hook spring; Fig. 55 the forward or side-action swivel, and are used in bar locks.
Fig. 56 is the back-action mainspring, such as used in cheap made locks. These springs are also made with sear spring combined. Fig. 57 is swivel back-action with sear spring combined.
Figure 54.
Sear Springs.—Sear springs are made for right and left hand locks. The side-action or bar-lock springs are shown in Fig. 58, and the back-action lock springs in Fig. 59. In one kind of back-action lock there is used a bent spring similar to the bar-lock spring which is shown in Fig. 60. It will be observed that the lower branch of this spring is longer than that which is used in the bar or side-action locks.
Figure 55.
How to Forge Mainsprings.—If the gunsmith desires to forge his own mainsprings he must select a good quality of spring steel, as cast steel is generally too quick or fiery for springs that have as severe a duty to perform as a mainspring. Get the steel of the same thickness as the mainspring and of a width equal to the spring and the pivot that goes through the lock plate.
Figure 56.
Draw the spring out carefully over a fire that has been burned enough to free it from sulphur, if bituminous coal be used, and be very careful not to over-heat the metal. Form to shape with any tools or means that may be at hand.
For straight springs, as some kinds of pistol and gun-lock springs, procure steel of the thickness and width of the spring at the widest and thickest end, and draw down to the requisite width and thickness of the smallest end.
Figure 57.
How to Temper Mainsprings.—If it be a single spring that is to be tempered, heat it carefully or evenly in a fire that is well burned to free it from sulphur, or preferably in a charcoal fire, and when at a light-red heat, harden by plunging it in any animal oil. An iron pan may be used to contain the oil, and any refuse or poor oil that may collect may be used. Lard oil is good, but if oil be wanting, use common lard or even tallow. If hard, melt before using.
Figure 58.
To temper the spring, remove from the oil, and hold it all dripping with the oil over a clear fire until the oil takes fire and blazes off. It is best to dip it in the oil and blaze off the second time.
Figure 59.
If there are a number of springs enclose them in a piece of gas pipe to heat them, and when hot, turn them into the oil. To temper, remove them, put them in an old wrought-iron frying pan, add a little oil, heat the pan over the fire, shaking it in the meantime, until the oil takes fire and blazes off. Let the work cool without putting it in water or oil.
Figure 60.
Cheap Mainsprings for Revolvers.—Make springs for cheap revolvers from strips of sheet steel. Cut the springs so that the length of the spring will be lengthwise of the sheet from which it is cut, or, in other words, the grain of the steel must not be across the spring, but lengthwise with it.
When fitted, harden in oil and blaze off in an old sheet-iron pan; an old frying pan being very good for the purpose, and literally fry them in the oil. If heavy, blaze two or three times. Agitate well in the pan during the blazing process.
An old saw blade, one that is quite thin, when cut up in strips will make springs for cheap work. If too hard temper, it cannot very well be used until the temper be drawn to suit. They can be bent into form with a strong pair of pliers. By warming the strips over a fire they can be readily bent into shape. Old table-knife blades, sometimes called case-knife blades, that are well tempered, have been employed, the blades being cut lengthwise with a pair of hand shears.
Coiling Wire for Springs, &c.—There are several methods of coiling wire for springs. The most simple is to clamp a rod in the vise and wind the wire around it by hand, but this is a very unsatisfactory method and it is rather difficult to wind the wire evenly. Another method is to revolve a rod in the lathe and let the wire coil upon it as the lathe is turned. To insure equal space between the coils, a piece of metal is held “behind” the wire, and as this piece of metal bears against, or in advance of the coil just made, it produces an even spring. A hook made of a piece of wire or a piece of metal with one end formed into a hook and clasping the rod on which the wire is moved is an excellent way to form an even spring. Two, or even three or more pieces of wire may be wound at one time, and this will insure springs of even space.
Another way in which a spring of even coil can be made, is to hold a bolt that has a good thread, upright in the vise and confine the wire by clamping it to the bolt, then wind the wire, letting it follow the thread of the bolt. When enough is wound, remove and release the spring by “screwing the bolt out of it,” the same as if holding a nut fast in the hand and turning the bolt out of it. Springs of almost any coil, but not of “almost any diameter,” can be made in this way.
Figure 61.
In the absence of a lathe a wire winding tool may be made by bending a rod into the form of a crank and insert the long end through a piece of hard wood, as shown in Fig. 61. This can be held in the vise to use, or fastened by two or three screws to the bench or any convenient place. A slot is made in the end of the part that projects through the wood, and in this slot the end of the wire is placed and is wound toward the crank. Of course the spring can be made no longer than this projecting end. To make different sized springs different sized rods must be used, and holes to fit must be made through the piece of wood.
To insure even space between the coils, a strip of thin steel may be fastened by one or two screws at or near the bottom of the piece of wood, and a hole is made near the top of the winding rod to pass through. A space is cut out, as shown in the cut, to admit of the wire being removed. In winding the upper end the steel strip is held away from the wood by its spring, or by a wooden wedge, and the wire must be held close to the wood by the hand or by a piece of wire formed as a sort of staple. To wind a very long spring, or a spring longer than the rod, a clamp may confine the wire to the rod, and when the spring has been wound to its length, remove the clamp, draw back the winding rod, fix the clamp close to the outer end and begin to wind again without cutting the coil, push it off the end of the rod as it is filled each time. As all wire, like hard drawn brass or steel wire, will “spring open” after being coiled, the rod must be made much smaller than the spring to be formed. Different sized holes may be made in the same block of wood to receive different sized winding rods over.
Hooks or eyes on the ends of the rods can be readily made in like manner. When the rod is too large to admit of ready bending to form the crank to turn it with, a crank of cast-iron can be riveted upon it.
If the mechanic wishes to make a tool of this kind, that will be more serviceable and at the same time “look like something,” he can procure a casting similar to the movable head of a lathe, and put in the hole where the spindle is placed a similar spindle, but with the end where the wire is to be wound large enough to form a shoulder to keep it in place, and on the other end put a wheel eight or ten inches in diameter, with a handle to turn it with. The end where the shoulder is may be made with a screw to fit the lathe chuck or with a hole to receive the lathe tools, and they can be held there the same as holding them in the lathe chuck. The spindles to wind the wire may be inserted in the hole and held in place by the set-screw. The tool may be fastened to the bench by a rod screwed into the base, or held by a nut under the bench.
This tool will be found to be a very ready one with which to work out bullet moulds. The cherry being held the same as a rod. It can also be used to free the muzzle or breech of barrels, using the wooden rods covered with emery, as described in Chapter XVI. It is also useful for reaming holes and can be used for drilling in case of an emergency. As a tool for holding taps to tap the thread in holes it has no equal—the work being held in the left hand and the wheel turned with the right hand.