Bolt (hardware)

“ This causes the knob shanks, when rotated, to bind, or stick, in the sleeve, or collar, of the escutcheon, thereby holding back the latch bolt after the latch is withdrawn into the lock case. It is also found that proper adjustment is seldom given to the knobs and spindles passing through the escutcheons. In many cases when the hardware is applied carelessly, the owner, not knowing the real cause of the trouble, condemns the best hardware as being cheap and unsatisfactory. ”

“ A black bolt is one left as forged. A finished bolt has its body, and usually its head also, machine finished, but a finished bolt sometimes has a black head, the body only being turned.
A square-headed bolt usually has a square nut, but if the nut is in a situation difficult of access for the wrench, or where the head of the bolt is entirely out of sight (as secluded beneath a flange) the nut is often made hexagon. A machine-finished bolt usually has a machine-finished and hexagon nut. Square nuts are usually left black. ”

“ One of the most numerous details in the structure of all classes of machines is the bolts which serve to hold the various parts together. As it is most important that each bolt fits perfectly the hole it belongs to, it is requisite that each bolt should, by the process of turning, be made perfectly cylindrical. In preparing such bolts, as they come from the forge, in order to undergo the process of turning, they have to be "centred;" that is, each end has to receive a hollow conical indent, which must agree with the axis of the bolt. ”

“ In shops where bolt-making is of frequent occurrence a special bolt-making device is usually employed. It consists of an oliver or foot hammer, having two hammers and an anvil; in the square hole at one end of the anvil fits a hardy or bottom chisel, such as shown in Fig. 2908, for cutting up the bar or rod iron into bolt blanks; a is the anvil, h the hardy, and g a gauge to determine the length cut off the rod r to form a blank. An upsetting or heading device corresponding to that in Fig. 2907 is provided, and at the other end of the anvil is the swage for forming the bolt head. ”

“ When a bolt has no head, but is intended to screw into the work at one end, and receive a nut at the other, it is termed a stud or standing bolt. The simplest form of standing bolt is that in which it is parallel from end to end with a thread at each end, and an unthreaded part in the middle, but since standing bolts or studs require to remain fixed in the work, it is necessary to screw them tightly into their places, and therefore firmly home. ”

“ It is easier to repair work that has tapered bolts than work that has straight bolts. If you adopt a tapered bolt, say, with a taper of 1⁄16 inch to the foot, you are going to effect the making of those bolts and the boring of those holes in a commercially accurate manner, so that they can be brought into the interchangeable system. ”

“ In machines in which the bolt rotates, the machine must be stopped to take out each finished bolt and insert the blank one, which is unnecessary when the bolt is stationary, because so soon as the bolt is threaded to the required distance the dies may open automatically, the carriage holding the bolt at once withdrawn and a new one inserted. ”

“ As the commission given to me calls for a decision as to the taper of bolts used in locomotive work, it presupposes that taper bolts are a necessity. In our own practice we divide bolts into several classes, and our rule is that in every case where a through bolt can be used it must be used. If we cannot use a through bolt we use a stud, and where a stud cannot be used we put in a tap bolt, and the reason why a tap bolt comes last is because it is part and parcel of the machine itself. ”

“ It is possible in fastening a machine or locomotive together to use black bolts and body bound bolts. With body bound bolts it is customary for machine builders to use a straight reamer to true the hole, then turn the bolt and fit it into its place. It is held by many locomotive builders that the use of straight bolts is objectionable, on the score that if they are driven in tight there is much difficulty in getting them out, and where they are got out two or three times they become loose, and there is no means of making them tighter. ”

“ As in that case nothing is to be added, a mechanical provision should be made to prevent the bolt from engaging in the teeth of the wheel which acts upon the dial above: the wedge which causes the bolt to be withdrawn, is thrown into such a position as to render it impossible that the bolt should be shot, or that it should enter between the teeth of the wheel, which in other cases it drives. But inasmuch as the usual means of shooting the bolt would still act, a strain would necessarily take place in the parts of the mechanism, owing to the bolt not yielding to the usual impulse. ”

“ It has been found from experiments that have been made that our present threads are stronger than their bolts, which is desirable, inasmuch as it gives a margin for wear on the sides of the threads. But for threads whose nuts are to remain permanently fastened and are not subject to wear, it is questionable whether it were not better for the bolts to be stronger than the threads. Suppose, for instance, that a thread strips, and the bolt will remain in place because the nut will not come off the bolt readily. ”

“ The American lock consists of a series of disks mounted upon one spindle, only one, however—the bolt disk—being fixed thereto, and provided each with a gating into which a stump connected with the bolt can drop when all the gatings lie upon a given line parallel to the axis of the spindle. Each disk is provided with a driving pin so arranged that it can impinge on and drive a similar pin in its next neighbour; the gating in the bolt disk and the portion of the stump which enters it are so formed that the disk can draw the bolt back. ”

“ It is evident at a glance, that unless the various steps of the key are so cut, that each shall press down its own lever to the proper extent, the ends of the levers cannot pass the notches in the plate, and the bolt can neither be locked nor unlocked. ”

“ One of the most useful applications of the screw is met with in the common bolt and nut, shown in Fig. 45. It consists of a wrought iron rod with a head at one end and a screw on the other, upon which the nut works. Bolts in many different sizes and forms represent the stitches by which machines and frames are most readily united. There are several reasons why the bolt is so convenient. It draws the parts into close contact with tremendous force; it is itself so strong that the parts united practically form one piece. ”

“ In single-pointed tools, such as are used upon lathe work, this has but little significance, because it is the work of but a minute or two to grind up the tool to a full point again, but in taps and solid dies, or in chasers in heads (as in some bolt-cutting machines) it is highly important, because it impairs the fit of the threads, and it is difficult to bring the tools to shape after they are once worn. ”

“ The internal arrangements of the lock are as follow: Supposing the bolt to be shot, and to be about to be unlocked, the key, by the time it has made about one-third of a rotation, meets with a forcible resistance in the shape of an upright spring-bolt or detector of strong steel acting on the revolving cylinder. The key passes this detector, and arrives at the levers or tumblers. In the bolt-stud which works in the slot of these tumblers there is a small deep serrated notch on one side, corresponding to similar notches on each of the tumblers ”

“ In screwing the nut on, the threads conform one to the other, giving a bearing area extending over the full sides of the thread. The undercutting on the leading face of the bolt thread gives room for the metal to conform itself to the nut thread, which it does very completely. The result is that the nut may be passed up and down the bolt several times and still remain too tight a fit to be worked by hand. Experiment has demonstrated that it may be run up and down the bolt dozens of times without becoming as loose as an ordinary bolt and nut. ”

“ When the countersunk head bolts are fitted they should be turned down behind the head, so as to leave a part weaker than the bolt, and then screwed in until the required end breaks off. The taper bolts should be of steel, but those with countersunk heads may be of iron. ”

“ On these bolting axes are fixed, so as to revolve with them, a bolting finger opposite to each bolt; as the bolting axis is made to revolve by the moving power, the bolting finger is turned, and as it passes near the bolt, it encounters the shoulder of a hammer or lever, which strikes the heel of the bolt, and presses it forward so as to shoot its tooth between the crown teeth of the adding wheel. The only exception to this action is the case in which happens to be at the index of the figure wheel ”

“ When a person who was outside wished to enter, it was necessary for him to insert the key in a little hole and to raise the bolt; and in time this species of fastening was improved by the insertion of the bolt in an iron frame or rim permanently attached to the door by a chain, and fastening the door by the insertion of the hasp, through the eye of which was forced the bolt inside the lock by applying the key. ”

“ Use square head bolts if you expect to take them out after the nuts have rusted on.
Figure 86.—Plow bolts and sickle bar bolts should be kept in stock. Standard sizes and shapes are made for several different makes of plows and machines.
Taps and dies are made to fit each size of rod. If the thread on the bolt is cut with a solid, or round, plate die, the corresponding tap is run clear through the nut. In that case the nut will screw on the bolt easily, possibly a little loose for some purposes. It is so intended by the manufacturers to give the workman a little leeway. ”

“ In the case of the nut there is sufficient elasticity in the thread to allow of the nut forcing itself to a bed on the work, the bolt bending; but in the case of the bolt head the bending is very apt to break off the bolt short in the neck under the head. In a tap bolt where the wrench is applied to the bolt head, the rotation, under severe strain, of the head will usually cause it to break off in all cases where the bolt is rigidly held, so that it cannot cant over and allow the head to bed fair. ”

“ In addition to this Chatwood’s (and we believe other makers’) safes have bolts so constructed, as seen in the figure, that they hook or lock into the bolt recesses in the frame in such a manner as to hold the opposite sides of the frame together, so that, independent of its own proper stiffness, it cannot be bent anywhere, unless by tearing asunder the end on the iron bar constituting each cross-bolt. ”

“ Let it now be noted that from the hardening process the taps shrink in length and become of finer pitch, while the dies expand and become of coarser pitch, and that this alone precludes the possibility of having the nut threads fit perfectly to those on the bolt. It becomes apparent, then, that only by cutting the threads in the lathe, and with a single-toothed lathe tool that can be ground to correct angle after hardening, can a bolt and nut be theoretically or accurately threaded. ”

“ With a little practice wire may be wound close enough to prevent slipping.
Home-made Bolts.—The easiest way to make a bolt is to cut a rod of round iron the proper length and run a thread on each end. On one end the thread may be just long enough to rivet the head, while the thread on [53] the other end is made longer to accommodate the nut and to take up slack. A farmer needs round iron in sizes from one-fourth inch to five-eighths inch. He will use more three-eighths and one-half inch than any other sizes. Blank nuts are made in standard sizes to fit any size of round iron. ”

“ If the countersunk head be lengthened so as to take up the whole of the unscrewed part of the bolt, we get the taper bolt shown in fig. 14, which is often used in the couplings of the screw shafts of steamships. The taper bolt has the advantage of having no projecting head, and it may also be made a tight fit in the hole with less trouble than a parallel bolt. Bolts may also have hexagonal heads. ”

“ A plain tap bolt should be turned up along its body, because if out of true the hole it passes through must be made large enough to suit the eccentricity of the bolt, or else a portion of the wrench pressure will be expended in rotating the bolt in the hole instead of being expended solely in screwing the bolt farther into the work. ”

“ To the end of the shaft is soldered a piece of wire, bent as shown in the sketch. A bolt is attached to the center of the motor base, so that its threaded end will pass through the slot in the upright, where it is held with a wing nut. ”

“ The bolt-gripping dies are shown at e f. A treadle g is pivoted at h, and acts upon the lower end of d, causing the die f to grip or release the bolts, as may be required. The bolster-pin rests upon the end of the screw i, which enters at its foot a split nut j, which is caused to grip and lock the screw by operating the nut of the bolt k that passes through the split of the nut. l is a spring that lifts the treadle when it is relieved of the pressure of the operator’s foot.
At m is a leather washer to protect the nut j from the scale that falls from the forging. ”

“ Nuts that require a severe wrench force to wind them on the bolt, may, even though they be as large as a two-inch bolt, often be made to pass easily by hand, if while upon the bolt they are hammered on their sides with a hand hammer. The action is in both cases to cause the sides of the thread to conform one to the other, which they will the more readily do in proportion as their sides are more acute. ”