Drilling machine

“ There is a circular saw that cuts through bars of iron as thick as railway rails, by making upwards of 1,000 revolutions per minute. A rivet-making machine forms the rivet, and shapes the head to the requisite size, with great accuracy and quickness. There are compound drilling machines, in which six drills are acting simultaneously; hydraulic presses, that force parts of machines together, and a great variety of other engines for the saving of time and labour. ”

“ The rates of feed are proportioned to the kind of drilling to be done. When the back gear is not in use and small drills are to be driven, the range of feeds is through a finer series than when the back gear is being used, and large drills or boring bars are [I-431] to be driven.
Fig. 1679 represents a drilling machine of English design. The cone pulley a is provided with back gear b placed beneath it, the live spindle driving the drill spindle through the bevel gears c, one of which is fast upon a sleeve d through which the drill spindle e passes. ”

“ At the present day, the turning and fitting shops are furnished not only with the slide lathe, self acting in both directions, and screw-cutting, the drilling-machine, and the screwing machine, but with planing machines competent to plane horizontally, vertically, or at an angle; shaping machines, rapidly reciprocating, and dealing with almost any form of work; nut shaping machines, slot drilling machines, and slotting machines, while the drills have become multiple and radial ”

“ Machine vs. Hand-Drilling.—The advantages of hand-drilling over machine-drilling lie, first, in the total saving of power, the absence of capital cost, repairs, depreciation, etc., on power, compresser Page 150 and drill plant; second, the time required for setting up machine-drills does not warrant frequent blasts, so that a number of holes on one radius are a necessity, and therefore machine-holes generally cannot be pointed to such advantage as hand-holes. Hand-holes can be set to any angle, and by thus frequent blasting yield greater tonnage per foot of hole. ”

“ Fig. 1796 represents a flexible shaft for drilling holes inaccessible to a drilling machine, and in situations or under conditions under which a ratchet brace would otherwise require to be used. It consists of a shaft so constructed as to be capable of transmitting rotary motion though the shaft be bent to any curve or angle. A round belt driven from a line shaft rotates the grooved pulley, and the shaft transmits the rotary motion to bevel-wheels contained in a portable drilling frame, the fulcrum for the feed being afforded by a drilling post after the manner employed in ratchet drilling. ”

“ Holes that are to be made parallel, straight, cylindrically true in the drilling machine, are finished by the reamer as already described with reference to lathe work, and it is found as in lathe work that in order that a reamer may finish holes to the same diameter, it is necessary that it take the same depth of finishing cut in each case, an end that is best obtained by the use of three reamers, the first taking out the irregularities of the drilled hole, and the second preparing it for the light finishing cut to be taken by the third. ”

“ Before we men of the study blame the general body of people for remaining unaffected by reforming proposals of an almost obvious advantage, it would be well if we were to change our standpoint and examine our machinery at the point of application. A rock-drilling machine may be excellently invented and in the most perfect order except for a want of hardness in the drill, and yet there will remain an unpierced rock as obdurate as the general public to so many of our innovations. ”

“ It is capable of drilling locker shells of any diameter between four and eight feet. The feed motion to each drill is driven from one source of power, but each drill is adjustable on its own account. The depth of feed is regulated by a patent detent lever which engages with the teeth of a ratchet wheel, till released therefrom by contact with the adjustable stop. The drill spindle is then instantly forced back by the spiral spring and the forward feed motion continues. ”

“ 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. ”

“ For soft rock, single-hand drilling is from 20 to 30% cheaper than double-hand, but this difference does not hold good for the harder rocks. For these double-hand drilling is preferable, and may even be essential, to secure a reasonable speed of work.
Machine Drills.—The introduction of machine drills in the latter part of the 19th century exerted an important influence on the work of rock excavation in general, and specially on the art of mining. By their use many great tunnels and other works involving rock excavation under adverse conditions have been rapidly and successfully carried out. ”

“ Machine Boring. —In machine drilling, the operations necessarily differ somewhat in their details from those of hand boring, and, in some cases, other methods of procedure will be adopted more suitable to the requirements of machine labour. It may even be, and in most cases indeed is, inexpedient to follow closely the principles which lead to economy of the explosive substance employed, since the more restricted conditions under which machine power may be applied may point to more important gains in other directions. ”

“ The choice between hand and machine drilling depends chiefly on the kind of rock and the size and depth of shaft. For very hard 'rock or when rapid work is desired, machine drilling is advisable, a compressor and additional boiler capacity being then required. Remarkable speeds, however, have been made by hand-sinking in some of the deep vertical shafts on the Rand, the w0rld's record being that of the Howard shaft, sunk by hand labour 203 ft. ”

“ It requires to have all rivet holes drilled, and it must be carefully annealed, though the writer is informed by Mr. Edwin Danks, of Oldbury, that steel makers often prefer to have their plates either worked cold or at a red heat, and not in the intermediate condition. Drilling machines especially designed are now used. Hydraulic machines of greatly improved construction have come into use for facilitating the operations in the boiler yard. ”

“ Power Drilling.—In power drilling the drill is driven by a reciprocating machine which either strikes and turns the drill in the hole, or lifts and turns it as in churn drilling, or the drill may be driven by a rotary machine which is revolved by compressed air, steam, or electricity. ”

“ With the improvement of the methods of drilling, and the debut of the rotary system, it has been possible not only to drill to much greater depths, but to considerably reduce the time requisite for drilling a well to the oil sands. Californian records for quick drilling with the rotary machine show that wells have been got down to the producing sands, in some fields nearly 4,000 feet below the surface, within one month. ”

“ Actually there is one man to each ten machines, to keep the long brass or steel rods passing into their busy wheels and tools, to maintain and regulate the flow of lubricant which runs constantly on each cutting tool. In this factory there are automatics drilling out the rifle-barrels, the drill pressing in so far at a time, when the machine carefully withdraws it for a busy little steel hand to poke forward and fussily brush off the grit and chips and clear the drill, which then slides smoothly114 back and goes on with its job. ”

“ The results obtained in South Africa by hand-drilling in shafts, and its very general adoption there, seem to indicate that better speed and more economical work can be obtained in that way in very large shafts than by machine-drilling. How far special reasons there apply to smaller shafts or labor conditions elsewhere have yet to be demonstrated. In large-dimension shafts demanding a large number of machines, the handling of long machine bars and machines generally results in a great loss of time. ”

“ To effect this progress of 120 feet, probably about 3,000 holes have been drilled in an area not exceeding 24 feet by ten feet, requiring twelve drilling machines, and 60 horse steam power to compress the air requisite to drive the drills; add to this the powder, over a ton and a half, the electric exploders, the candles and oil for miners, and the fact that a mass of rock 120 feet long, ten feet high and twenty-four feet wide, has to be carried out and dumped two miles from where it was excavated, and some slight idea of the labor at this one point may be formed. ”

“ The duty of a skilled white man, single-handed, in rock such as is usually met below the zone of oxidation, is from 5 to 7 feet per shift, depending on the rock and the man. Two men hand-drilling will therefore do from 1/4 to 2/3 of the same footage of holes that can be done by two men with a heavy machine-drill, and two men hand-drilling will do from 1/5 to 1/2 the footage of two men with two light drills. ”

“ Rotary Drills. —Rotary drilling machines, or more simply rotary drills, were first used in 1857 in the Mont Cenis tunnel. The advantages claimed for rotary drills in comparison with percussion drills are: (1) That less power is required to drive the drill, and the power is better utilized; (2) once the machines work easily they do not require continual repairs, and (3) in driving holes of large size the interior nucleus is taken away intact, thus reducing work and increasing the speed of drilling. Rotary drills are extensively used for geological, mining, well-driving, and prospecting purposes ”

“ The stop gages on some machines, instead of being held in the turret, are attached to a swinging arm or bracket that is fastened to the turret slide and is swung up in line with the spindle when the stock is fed forward.
The center drilling tool D is designed to hold a standard combination center drill and reamer. This type of tool is often used when turning parts that must be finished afterwards by grinding, to form a center for the grinding machine. The adjustable turning [203] tool E is used for turning the outside of gear blanks, pulley hubs or the rims of small pulleys. ”

“ When the pieces are cut from a rod or bar in a cutting-off machine, the ends are square, and they may be utilized to set the work by in centring it. Thus, in Fig. 1165 is a top, and in Fig. 1166 is an end view of a simple device, or lathe attachment for centre drilling. s is a stand bolted to the lathe shears and carrying two pins p, which act as guides to the cup chuck or work guide g; between the heads of pins p and the hubs of g are spiral springs, forcing it forward, but permitting it to advance over the drill chuck; the work w is fed forward to the drill. ”

“ At the East heading, partly owing to the rock being softer than either at the West End or in the Central Shaft, partly to the miners being accustomed to powder, partly to the heavy battery of drills enabling twelve drilling machines to work at once, and thus make progress satisfactory to the contractors, who, wisely, let well enough alone, the holes when drilled to a depth of from two feet six inches to three feet, are each charged with from one to two and one-half pounds of blasting powder, then tamped ”

“ For the mines which now turn out 2000 tons a day can by no means be counted on one’s fingers, and 2000 tons means more than a foot deep over a whole city block. Before the middle of the century the use of powder and drill had largely increased, and in 1845 an attempt was made to aid the man behind the drill with a machine which swung a hammer by steam power. In 1805 a machine was invented using compressed air in a cylinder, and this was gradually improved until it became a success in 1861, in the Mont Cenis tunnel. ”

“ When working with rock drills, a shaft can be sunk 10 to 20 feet a month, against 7 to 8 feet by hand, and a level may on the average be driven 45 to 50 feet a month by rock drills against 10 or 12 feet by hand. When, however, a large surface for operating on is exposed, hand-drilling may be profitably employed. This is interesting as illustrating the fact that where labour is cheap machines seldom pay, and this is particularly worth mentioning for the benefit of those who have thought that it would be useful to introduce agricultural machinery into India. ”

“ The boom of the drilling rig as it raises and drops the drill provides the necessary impact. With the core method, as its name implies, a hollow boring drill cuts its way aided by steel shot and a flow of water forced through the pipe that rotates the cutting tool.
With either method the results are the same. Sooner or later the drill will reach an underground water course of sufficient size to give an ample flow. As such drilling is done on a charge of three to five dollars a foot, the owner, of course, hopes for sooner. ”

“ The large charges in deep holes break the walls very irregularly; misfires cause more delay; timbering is more difficult in the face of heavy blasting charges; and the larger amount of spoil broken at one time delays renewed drilling, and altogether the advantages seem to lie with hand-drilling in shafts of large horizontal section.
The rapid development of special drills for particular conditions has eliminated the advantage of hand-work in many situations during the past ten years, and the invention of the hammer type of drill bids fair to render hand-drilling a thing of the past. ”