Entrenching tool

“ For the details of the defence of walls, houses, &c., see the official Mil. Engineering (1908) .
Entrenching under Fire.—Progress in this direction has been delayed by the reluctance of military authorities to add a portable entrenching tool to the heavy burden already carried by the infantry soldier. Further delay has resulted from the attempts of enthusiastic inventors to produce a tool that shall weigh nothing, go easily in the pocket, and be available as a pick, shovel, saw, hand-axe or corkscrew. A tool that will serve more than one use is seldom satisfactory for any. ”

“ It is singular, that with the immense variety of tools set forth in the preceding chapter, how few, really, require the art of the workman to grind and sharpen. If we take the lathe, the drilling machine, as well as the shaper, planer, milling machine, and all power-driven tools, they are merely mechanism contrived to handle some small, and, apparently, inconsequential tool, which does the work on the material. ”

“ The natural tendency is to slack up or stop the motion of the treadle while the tool is engaged, and the tool is, therefore, at one time under the work, at another time above it, at another jumping rankly in, until, finally, the piece goes whirling out of the center or the chuck, and the operator flushes all over at his awkwardness. ”

“ To the learner, practice with hand tools is especially advantageous, inasmuch as the strain due to the cut is felt by the operator; hence, the effects of alterations in the shape of the tools, its height or position with relation to the work, and also the resistance of the metal to severance, are more readily understood and appreciated than is the case where the tool is held in a slide rest or other mechanical device. ”

“ In using small drills in a machine it is of the first importance that the amount of pressure necessary to feed the drill be plainly perceptible at the hand lever or other device for feeding the drill or the work, as the case may be, as any undue pressure causes the drills to break. To attain sensitiveness in this respect the parts must be light and easy both to move and to operate.
Fig. 1671 represents the American Tool Company’s delicate drilling machine for holes of 1⁄4 inch and less in diameter. ”

“ This is necessary when the spindle of the machine in which it is used has play in the bearings, which is very often the case with boring and drilling machines. The use of g is to act as a guide fixed in the table upon which the work is held, to prevent the tool from springing away from the cut, and hence enabling it to do much smoother work. ”

“ Then chuck and re-chuck to familiarize yourself with every operative part of the lathe, and never try to force the cutting tool. If it has a tendency to run into the work, set it higher. If, on the other hand, you find, in feeding, that it is hard to move the tool post along, the tool is too high, and should be lowered. ”

“ 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. ”

“ Now-a-days, the twist drills, made and sold in all the tool stores, are so uniformly superior to any thing that can be made by hand, or by individuals, and are, moreover, so cheap, that it is foolish to make drills. ”

“ These tools can be used for a wide variety of ordinary turning operations. When a great many duplicate parts are to be machined, special tool equipment can often be used to advantage, but as the form of this equipment depends upon the character of the work, only standard tools have been shown in this illustration. The tool shown at A is a right-hand, roughing tool, and a left-hand tool of the same type is shown at B. Tool C is an offset or bent, left-hand round nose for roughing, and D is a right-hand offset roughing tool. ”

“ In brief, the present is an age of an increased development of machine instead of manual treatment, which has gone far to revolutionise the machinery used in spinning. Every student who may hereafter be engaged in the construction of this class of machinery should impress firmly upon his mind the fact that the machine tool is the best instrument for his purpose, and should develop it as far as possible. A special tool is invaluable, and the opportunities for its use are always increasing. ”

“ It will now be obvious that to produce work as nearly cylindrical as possible, the tool edge should stand as near to the slide rest as the circumstances will permit, which will hold the tool more firmly and prevent, as far as possible, its deflection or spring from the cut pressure. ”

“ Of course there is a difference in them so far as skill is concerned, but everyone can grind a chisel or plane-iron."
"One of the boys invented a piece of apparatus by which any desired bevel can be given to a tool at the grindstone," interposed Mr. Jepson, as he exhibited the machine to the visitors. ”

“ The tool is thus in complete command, and the slightest change of pressure on either hand may alter its direction or stop it altogether. Never drive a tool forward with one hand without this counter-resistance, as there is no knowing what may happen if it slips. ”

“ Varieties of Active Capital Goods.—Mere hand tools act as armatures attached to the person of the worker, and they enable him effectively to attack resisting substances. The hammer fortifies the blacksmith's hand against the injuries it would [Pg 22] suffer if he delivered blows with his fist, and it multiplies the efficiency of the blows. Machines, however, substitute themselves for the person of the worker and carry the tool through its movements. ”

“ The front face should have little or no clearance, because it causes the tool to dig into the work. A tool so shaped will clear itself well on the back stroke, whereas if but little clearance and front rake be given as in Fig. 1652, the tool will not only dig in, but its cutting edge will rub on the back or return stroke. ”

“ The machine is supported upon a stand or framing which varies in form according to the situation in which it is to be used. This support is in all cases constructed to allow of the feed motion taking place, and also of the cutting tool being directed at any angle. The support for a rock drill constitutes an indispensable and a very important adjunct to the machine, for upon the suitability of its form, material, and construction, the efficiency of the machine will largely depend. ”

“ The engineer's plane more resembles the turning-lathe, of which indeed it is but a modification, working up on the same principle, on flat surfaces. The tools or cutters in Clement's machine were similar to those used in the lathe, varying in like manner, but performing their work in right lines,—the tool being stationary and the work moving under it, the tool only travelling when making lateral cuts. ”

“ DRILLING MACHINES
Everybody knows that oil wells and derricks go together. The tall derrick towers are needed to hoist drilling equipment in and out of the hole.
When men start to drill a well, they fasten a cutting tool, called a bit, to a piece of pipe which hangs upright{70} in the derrick. Machinery turns the whole thing round and round, so that the bit grinds down into the earth. When one length of pipe, called a joint, has almost disappeared into the hole, men screw another joint onto the top of it. Now the engine turns the double-length pipe, and the bit digs down deeper. ”

“ As the sizes of planing machines increase, they are given increased tool-carrying heads; thus, Fig. 1562 represents a class in which two sliding heads are used, so that two cutting tools may operate simultaneously. Each head, however, is capable of independent operation; hence, one tool may be actuated automatically along the cross slide to plane the surfaces of the work, while the other may be used to carry a cut down the sides of the work, or one tool may take the roughing and the other follow with the finishing cut, thus doubling the capacity of the machine. ”

“ To work with dull tools is altogether unsatisfactory. A boy should learn to sharpen his own edge tools. To grind a good bevel on a tool [Pg 12] like a chisel, it must rest upon something steady. The reflection of light on the newly ground surface will indicate whether the surface is flat or not. This process of grinding makes what is called a featheredge, or wire-edge, and the tool must be whetted on an oilstone to remove this wire-edge. The flat side must be kept flat on the stone; the bevel may be lifted just a trifle. ”

“ The simplest application of a principle of mechanics to an every-day hand-tool may convert it into what is called a machine. Take a three-pronged fork—one of the universal tools;—fasten a rope to the end of the handle; put a log under the fork as a fulcrum; and we have a lever, when pulled down by the rope, which will grub up a strongly-rooted large shrub in a few minutes. The labourer has called in a powerful ally. The tool has become a machine. ”

“ What the weight of the portable intrenching equipment of the Japanese, Russian, and British infantry will be, is still undecided, but experiments are being made with a uniform tool. When we consider, that for the purpose of intrenching, one man requires a space of 1.20 m., and for handling his rifle a space of 0.8 m., and that when intrenching under fire all the men cannot work, it is obvious that it would be impracticable [39] to equip each man with an intrenching tool. According to all experience, it is sufficient to furnish every other man with spade or pick. ”

“ As a matter of fact a fine machine-tool is more liable than a watch to get out of order through careless handling, and it no more than a watch, can be properly repaired by a bungler. It follows that skill in the use of machine-tools is as essential to a successful mechanical career now, as skill in the use of hand-tools was formerly. ”

“ To prevent any change of position, it is good practice, especially when roughing, to clamp the tool square with the surface being turned, or in other words, at right angles to its direction of movement. Occasionally, however, there is a decided advantage in having [62] the tool set at an angle. For example, if it is held about as shown at B, when turning the flange casting C, the surfaces s and s1 can be finished without changing the tool's position. Cylindrical and radial surfaces are often turned in this way in order to avoid shifting the tool, especially when machining parts in quantity. ”

“ When, however, the work had made another revolution, both the feed screw and the work would again come into position for the tool and nut to engage properly, and it follows that in this case the tool will always fall into proper position for the nut to be locked. ”

“ Specialization in machine-tool manufacture has been developed to such a degree that there is need also for treatises which specialize on different classes of tools and their application in modern practice. This book deals exclusively with the use of various types of turning and boring machines and their attachments, and is believed to be unusually complete. ”

“ Facing arms are attached to the bar on either side of the cylinder for facing the flanges after the boring operation. The turning tool of a facing arm is fastened to a slide which is fed outward a short distance each revolution, by a star-wheel that is caused to turn as it strikes against a stationary pin. ”

“ To illustrate, tool A is of a shape suitable for rough-turning large and rigid work, while tool B is adapted for smaller and more flexible parts. The first tool is well shaped for roughing because experiments have shown that a cutting edge of a large radius is capable of higher cutting speed than could be used with a tool like B, which has a smaller point. This increase [65] in the cutting speed is due to the fact that the tool A removes a thinner chip for a given feed than tool B; therefore, the speed may be increased without injuring the cutting edge to the same extent. ”

“ Let one man do the turning, another the chucking and another the faceplate work. Where buttons are used the toolmaker sets them at the bench, but the lathe hand can be instructed on the set-up and the use of the warbler and indicator. The same method can be used on the milling machine in boring holes for bushings, etc. If there is not enough turning the same man can do the boring. ”

“ It sometimes becomes convenient in the exigencies which occur in the work of a general machine shop to hold a drill in a dog or clamp and feed it into the work with the lathe dead centre. In this case the drill should be held very firmly against the dead centre, or otherwise the drill may, when emerging through the back of the hole, feed itself forward, slipping off the dead centre, and causing the drill to catch and break, or moving the work in the chuck, to avoid which the drill should have a deep and well countersunk centre. ”

“ Pressure is injurious not so much to the wheel as to the tool itself. The moment a tool becomes heated there is danger of destroying the temper, and the edge, being the thinnest, is the most violently affected. Hence it is desirable always to have a receptacle with water handy, into which the tool can be plunged, during the process of grinding down.
Correct Use of Grinder.—Treat the wheel asp. 28 though it is a friend, and not an enemy. Take advantage of its entire surface. Whenever you go into a machine shop, look at the emery wheel. ”

“ Whether one or two set-screws are used, the boring tool may be forged from a single bar of octagon steel, which can be seated in a piece like that shown at e in Fig. 610, which is grooved so as to receive and hold the tool. As is well known, boring tools are the most troublesome both to forge and to adjust in the lathe, and, as the result, a light tool is often used because no other is at hand and it is costly to make a new one. ”