Machining

“ And even this labour has now been got rid of; for, by an arrangement of the gearing, the slide itself has been made self-acting, and advances with the revolution of the work in the lathe, which thus supplies the place of the workman's hand. The accuracy of the turning done by this beautiful yet simple arrangement is as mechanically perfect as work can be. The pair of steel fingers which hold the cutting tool firmly in their grasp never tire, and it moves along the metal to be cut with an accuracy and precision which the human hand, however skilled, could never equal. ”

“ It may thus readily be seen that it is the little bar of metal from which the small tool is made that needs our care and attention.
This is particularly true of the expensive milling machines, where the little saw, if not in perfect order, and not properly set, will not only do improper work, but injure the machine itself.p. 27 More lathes are ruined from using badly ground tools than from any other cause.
In the whole line of tools which the machinist must take care of daily, there is nothing as important as the lathe cutting-tool, and the knowledge which goes with it to use the proper one. ”

“ Here is a huge planing machine travelling to and fro over a copper bar. A crank shaft has been cut out of solid steel by boring holes close together through a thick plate, and the two sides of the plate have been broken off, leaving the rough shaft with its edges composed of a considerable number of semicircles. The shaft is slowly rotated on a lathe, and tiny clouds of smoke arise as the tool nicks off pieces of metal to reduce the shaft to a circular shape. [138] Other machines, with high-speed tool steel, are finishing gear shafts. Fly-wheels are being turned and worm shafts cut. ”

“ We are able to machine the earth in much the same way as a piece of metal is machined in the machine shop. In fact, the drill, [252] the circular saw, the slotter, and even the milling machine have their counterpart in the excavating machinery of to-day. Of course we cannot expect to find the counterpart of such machines as the lathe, boring mill, and planer, in which the work revolves against the tool, because this planet of ours is rather too big a piece of stock to be placed between lathe centers or to be bolted to a planer bed. ”

“ In old times, before the invention and introduction of planing and shaping machines to work metals, the first and most important lesson taught to the machinist’s apprentice was the use of the hand-hammer and cold-chisel. When an outer shell was to be removed from a metal casting and its surface left in condition to be finished by file or scraper, the smoothness and regularity of that surface was essential, not only for economy in working, but accuracy of the file finish. ”

“ These men or women (for female labour is employed for polishing) hold the frames on grinding wheels or in some cases endless belts coated with emery, and they grind or polish the whole frame till it is bright and very smooth.
The frames and forks then go to the enamellers, a part of the factory we shall visit presently, when the other parts are ready for the painting process.
The Machine Shop is the department where all the parts that require turning, boring, milling, or profiling, are machined, as the various metal removing processes are termed. ”

“ In the practice of many tool makers in the Eastern States the tool is ground to a point a, Fig. 932, that is, ground sharp and merely rounded off with an oil-stone. This may serve when the lathe has an exceedingly fine feed, and the strain being in that case very slight the tool point may be made to stand well above the level of the body of the steel, as in the figure, and thus save forging; but this is a slow method of procedure, and produces no better work than a tool which is rounded at the point, and therefore capable of producing smoother work with a much coarser feed. ”

“ Such are among the triumphs of modern mechanical engineering, due in a great measure to the perfection of the tools by means of which all works in metal are now fashioned. These tools are themselves among the most striking results of the mechanical invention of the day. They are automata of the most perfect kind, rendering the engine and machine-maker in a great measure independent of inferior workmen. For the machine tools have no unsteady hand, are not careless nor clumsy, do not work by rule of thumb, and cannot make mistakes. ”

“ Practice is the only recipe for speed.
When the tool is shaped as well as possible on the anvil it is then finished with a file by clamping the new tool in the vise, using single cut files. Bastard files are too rough for tool steel. After the tool is shaped by cross-filing and draw-filing to make it smooth it is sometimes polished by wrapping fine emery cloth around the file. Oil is used with emery cloth to give the steel a luster finish. Tempering is the last process in the making of such tools as cold chisels, drills, dies, punches, scratchawls, etc. ”

“ The word is also applied to many mechanical devices by which raw material is transformed into a condition ready for use or into a stage preparatory to other processes, e.g. saw-mill, rolling-mill, &c., or still more widely to buildings containing machinery used in manufactures, e.g. cotton-mill. In mining it is applied to various machines used in breaking and crushing the ore (see Ore-Dressing) .
In the engineering industries milling machines constitute a very important class of machine tools, the characteristic of which is that rotary cutters are employed for shaping the metal (see Tools) . ”

“ The extended use of the milling machine, which is an especial feature of modern machine shop practice, is due, in a very large degree, to the solid emery wheel, which provides a simple method of sharpening the cutters without requiring them to be annealed and rehardened, it being found that annealing and rehardening reduces the cutting qualifications of the steel, and also impairs the truth of the cutting edges by reason of the warping or distortion that accompanies the hardening process. ”

“ We find, too, that on quantity production in toolroom, we are in a position to effect some very great savings in time and money, as it permits standard jigs and fixtures, such as in ordinary manufacturing; for instance, we at one time machined all our flat tool bits made of high speed steel before hardening and grinding, while our present method is to heat bars of steel in gas furnace and then punch out with die under heavy hammer or press. This method alone in a couple of hours gives us a supply ahead that would ordinarily take one machine or more in continuous operation to produce. ”

“ 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. ”

“ To coördinate a number of inanimate pieces of steel and iron, to operate at high speed with precision, requires fine skill. The evolution from the first cutting machine—the old hand-operated wooden plough and press—to the present power-driven steel mechanism is like the advance from the old wooden sailing vessel to the modern steel ship. ”

“ There are hundreds of drill press hands who cannot operate a milling machine, lathe hands who know nothing of planer work, and so on. The subdivision of these occupations follows closely the advance in invention, so that employers advertising for help frequently specify not only the machine tool to be used but add the name of the firm which manufactures that particular type of machine, with the result that there are about as many kinds of machinists as there are manufacturers of machine tools. ”

“ There is no economy in making men work with poor light, bad air and in a cold place.
Buying Machine Tools.—Having secured by lease or by purchase a shop, or factory suitably located your next effort will be directed toward equipping it with the proper tools and machinery.
Besides the usual machinists’ hand tools you should buy (1) a gas furnace; (2) a grinder; (3) a plain lathe; (4) a screw cutting lathe; (5) a drill press; (6) a planer; (7) a shaper; (8) perhaps a milling machine, and (9) a buffer. Several of each of these kinds of machines may be needed.
Fig. ”

“ The real problem is how to remove chips fast from a casting or a forging, and how to make the piece smooth and true in the shortest time, and it matters but little whether the piece being worked upon is part, say, of a marine engine, a printing-press, or an automobile. For this reason, the man with the slide-rule, familiar with the science of cutting metals, who had never before seen this particular work, was able completely to distance the skilled mechanic who had made the parts of this machine his specialty for years. ”

“ Let any one attempt to describe the much more simple and familiar process by which a shoemaker makes a pair of shoes, and he will find how inadequate mere words are to describe any mechanical operation. [13] Suffice it to say, that the machinery was of the most beautiful manufacture and finish, and even at this day will bear comparison with the most perfect machines which can be turned out with all the improved appliances of modern tools. The framing was of cast-iron, while the parts exposed to violent and rapid action were all of the best hardened steel. ”

“ A great deal of it, to be sure, was crude, but it was also practical; and when a piece of machinery would not perform well I went to work, and kept at it until it would, and in the end had not the slightest trouble in rolling, casting, drilling, planing, and turning iron or cast-steel, in all reasonable shapes. To be sure my machinery was not painted, or even well finished, except in the working parts, but to those sections I gave a mechanic's care. I not only worked here, however, on stormy days alone, but also nearly every spare moment that I had from other duties that were also pressing. ”

“ But actually so much is involved that subdivisions of tasks are numerous; the operations of templet-making, rolling, planing, punching and shearing, bending, welding and forging, flanging, drilling, riveting, caulking, and tubing require the labours of several groups of machine attendants, and of gangs of unskilled labourers or helpers. Some operations also have to be done at a red or white heat, others cold. To the first belong flanging and welding, to the latter generally all the other operations. Heating is necessary for the rolling of tubes of small diameter ”

“ Practice has shown the most effective way of treating different materials, so that the tools will do the most efficient work.
A tool ground in a certain way and set at a particular angle might do the work admirably on a piece of steel, but would not possibly work on aluminum or brass.
Lathe Speed.—If the lathe should run at the same speed on a piece of cast iron as with a brass casting, the result would not be very satisfactory, either with the tool or on the work itself.
Some compositions of metal require a high speed, and some a hooked tool. ”

“ Wherever there is a stream with a fall, there is the grinding-wheel at work: and in hundreds of workshops the nicer labour of the artificer is fashioning the steel into every instrument which the art of man can devise, from the scythe of the mower to the lancet of the surgeon. The machinery that made the steel has called into action the skill that makes the file-cutter. No machine can make a file. ”

“ There is no trade or occupation which calls forth the inventive faculty to a greater degree than the machinist's. Whether it be in the direction of making some new tool, needed in some special work, or in devising a particular movement, or mechanical expedient, the machinist must be prepared to meet the issues and decide on the best structural arrangement.
Opportunities also come daily to the workers in machine shops to a greater extent than other artisans, because inventors in every line bring inventions to them to be built and experimentally tested. ”

“ So delicate is the touch of some of these tools, so good the metal they are employed to cut, that shavings are taken off three or more feet long, curled up like a spiral spring, and which may be wound round the hand like string. The interiors of the cylinders, the bearings, those portions of the engines which slide one upon the other, and require the most accurate fit, are here adjusted by unerring machinery, which turns out the work with an ease and exactness which the hand of man, delicate and wonderful organ as it is, cannot reach. ”

“ A skilled mechanic sets the machine and the chucks which hold the work; an unskilled hand can continue the operations, his products being uniformly of the dimensions and forms desired. Intricate shapes are easily executed, quite impracticable on any other machine. At first the revolving mechanism and its cutters were a single piece of metal; to-day cutters of costly quality are inserted in cheap metal; these inserted cutters when worn out are easily replaced.
[99]
Iron planer; a, b, c, d, fixed cutting tools; M, moving bed.
Niles-Bement-Pond Co., New York. ”

“ An old description of the plant says that it consisted of
an iron foundry, mould-maker’s shop, steam engine manufactory, blacksmith’s shop, and mill-stone manufactory, and a steam engine used for grinding materials for the use of the works, and for turning and boring heavy cast or wrought iron work. The buildings occupy one hundred and eighty-eight feet front and about thirty-five workmen are daily employed. They manufacture all cast or wrought-iron work for machinery for mills, for grinding grain or sawing timber ”