Cutting tool

“ The cutting tool, shaped according to the pattern to be executed, is attached to the end of the screw; and the metal being held in a proper position beneath it, the fly is made to urge the tool downwards with such force as to stamp out pieces of the required figure. When the pattern is complicated, and it is necessary to preserve with exactness the relative situation of its different parts, a number of punches are impelled together, so as to strike the entire piece of metal at the same instant, and in this manner the most elaborate open work is executed by a single stroke. ”

“ If the cutting tool be made parallel and cylindrical on its edges, and clearance be given on the front end of its diameter only, so as to cut along a certain distance only of its cylindrical edge, the rest being a close fit to the bore of the work, the part having no cutting edge, that is, the part without clearance, will be apt to cause friction by rubbing the bore of the work as the tool edge wears, and the friction will cause heat, which will increase as the cut proceeds, causing the hole to expand as the cut proceeds, and to be taper when cooled to an equal degree all over. ”

“ The cutting tool imitating precisely the motions of the guide, enters the wood, and cutting its way in the most perfect manner and with incredible rapidity, forms an exact duplicate of the cavity in the pattern. The theory of this operation is sufficiently curious and striking—but the wonder excited by it is infinitely enhanced by seeing the work done. It is on this principle substantially that all the machines of the Stocking Shop are constructed; every separate recess, perforation, or groove of the piece requiring of course its own separate mechanism. ”

“ Fig. 997.
Figs. 996 and 997 represent a method of cutting a round top and bottom, or any other form of thread, by means of a single-pointed circular cutting tool, which is mounted on a holder. On the circumference of the cutter is cut a single thread, and a piece is cut out at e to form a cutting edge. To cut a right-hand thread on the work, a left-hand one must be cut on the cutter, so as to make its thread slant in the proper direction. The tool is sharpened by grinding the top face, and moved on the holding pin to set it to the proper height or in position to enable it to cut. ”

“ They are, therefore, the griping chuck; the supporting rest preceding the cutting tool; a cutting tool having the reciprocating motion to wards and from the axis of the piece to be operated upon, under the control of a guide cam or former, so organized as to be also under the constant control of delicate adjusting apparatus, by which the required diameter of a piece to be operated upon may be constantly preserved without disturbing the functional performance of former and cutting tool, substantially as set forth and described, all operating together for the purpose set forth. ”

“ First, work to be bored must be held (by bolts, plates, chuck-jaws, or similar appliances) with sufficient force to withstand the pressure of the cut taken by the cutting tool, and this pressure exerts more or less influence to spring or deflect the work from its normal shape, so that a hole bored true while clamped will not be so true when released from the pressure of the holding clamps.
To obviate this as far as possible, expert workmen screw up the holding devices as tight as may be necessary for the heavy roughing cuts, and then slack them off before taking the finishing cuts. ”

“ If a piece of metal is to be cut in a lathe, for example, there is one particular angle at which the cutting-tool must be held to insure the cleanest cut; and it is quite natural that the idea of fixing the tool at that angle should present itself to an intelligent workman. The necessity of moving the tool slowly, and in a direction parallel to itself, would suggest the use of a screw, and thus arises the sliding-rest. ”

“ In screw cutting the cutting tool requires to be withdrawn from the thread while the carriage traverses back, and it is somewhat difficult to know just how far to move the tool in again in order to put on a proper depth of cut. To facilitate this the device shown in Fig. 585 (which is taken from the “American Machinist,”) is sometimes employed.
It consists of a ring c inserted between the cross slide d and the handle hub b having journal bearing on and rotating with the latter. ”

“ The strength of a cutting forms to a great extent a guide as to the quality of the tool, since the stronger the cutting the less it has become disintegrated, and therefore less power has been expended in removing it from the work.
The cutting speed for wrought iron should be sufficiently great that water being allowed to fall upon the work in a quick succession of drops as, say, three per second, the cuttings will leave the work so hot as to be almost unbearable in the hands, if the cut is a heavy one, as, say, reducing the work diameter 1⁄2 inch at a cut. ”

“ The side of the roughing cutter A is ground to a slight angle c to provide clearance for the cutting edge, and the front has a backward slope s to give the tool keenness. This tool is a good form to use for roughing cuts in cast iron. The finishing tool at B has a broad flat edge e and it is intended for coarse feeds and light cuts in cast iron. If a round cutting edge is used for finishing, a comparatively fine feed is required in order to obtain a smooth surface. The corners of tool B are rounded and they should be ground to slope inward as shown in the plan view. ”

“ The amount of feed per revolution of the work, however, should always be less than the width w of the cutting edge. Very often broad tools cannot be used for finishing cuts, especially when turning steel, because their greater contact causes chattering and results in a rough surface. An old and worn lathe is more liable to chatter than one that is heavy and well-built, and as the diameter of the work also makes a difference, a broad tool cannot always be used for finishing, even though, theoretically, it would be preferable. ”

“ Another step in the direction of economy depends on the removal of all screw-cutting, except those screws which are of several feet in length, from the ordinary lathe to the special chasing and screwing machines. The screw-cutting arrangement of an engineer's lathe is a cumbrous apparatus to fit up and set in motion for the cutting of screws of small dimensions. When there was no other method available except that of common dies operated by hand or carried in a screwing machine, there was good reason why a true cutting tool should be operated in the lathe through change wheels. ”

“ When a tool has front rake only, the form of its cutting will depend upon the depth of its cut. With a very fine cut the cutting will come off after the manner shown in Fig. 940, while as the depth of the cut is increased, the cutting becomes a coil such as shown in Fig. 941. These coils lie closer together in proportion [I-259] as the top face of the tool is given less rake, as is necessary for steel and other hard metal. Thus Fig. 940 represents a cutting from steel, the tool having front rake only, while Fig. 941 represents a cutting from a steel crank pin, the tool having side rake. ”

“ The clearance is, however, reduced and the lip angle changed.
There is great danger when grinding a tool of burning it or drawing the temper from the fine cutting edge, and, aside from the actual shape of the cutting end, this is the most important point in connection with tool grinding. If a tool is pressed hard against an emery or other abrasive wheel, even though the latter has a copious supply of water, the temper will sometimes be drawn. ”

“ The cutter is carried 1n a head, with swiveling arrangements, to provide for variations in screw angles, and is rotated at speeds suitable for the metal or alloy being cut. The necessary traverse is imparted either to the work or to the cutter, according to the design of machine, by lead screw and change gears. This method is employed to a considerable extent, chiefly for cutting coarsely threaded screws and worms. The great advantage which the revolving cutter possesses over the single-edged tool is its rapidity of action, by which threads may be produced more quickly than in the lathe. ”

“ The multiplicity of cutting edges on a rotary cutter so increases its durability, and the intervals at which it must be sharpened are so prolonged, that, with the aid of the present improved cutter grinding machines, one tool maker can make and keep in order the cutters for many machines. ”

“ At B a tool of the same type is shown, having a bent end which enables it to be used close up to a shoulder or surface s that might come in contact with the tool-rest if the straight form were employed. Tool C, which has a straight cutting end, is used on certain classes of work for taking light finishing cuts, with a coarse feed. ”

“ If the tool gets dull too quickly and the cutting speed is not excessive, then the tool has too much clearance. If the tool edge breaks there is too much rake (providing of course that the tool has not been burnt in the forging or hardening) , a fine feed will generally produce longer and closer coiled cuttings (that is of smaller diameter) [I-260] than a coarse feed, especially if the work be turned dry or without the application of water.
Fig. ”

“ The formed milling cutter, which retains accurately the contour of its cutting edge through successive sharpenings, was invented in 1864 by J. R. Brown with special reference to the cutting of gear teeth. In fact, the oldest milling cutter known was used for cutting gear teeth. This cutter was made some time prior to 1782 by the French mechanic Jacques de Vaucanson and came into the possession of the Brown & Sharpe Manufacturing Company about 1895. The teeth are very fine and apparently were cut with chisels. ”

“ It is, indeed, a far better plan to take the tool (after grinding) and rub the cutting edge into a piece of soft wood, and to apply oil to the tool during its first two or three cutting revolutions. The application of oil will often remedy a slight existing chattering of a boring bar, but it is an expedient to be avoided, if possible, since the diameter or bore cut with oil will vary from that cut dry, the latter being a trifle the larger. ”

“ BOLT CUTTER.--O.E. Butler and S.P. Dunham Marshalltown, Iowa.--This invention relates to improvements in hand instruments for cutting bolts, and consists in the combination with the handles of an instrument, such as patented to the inventors, January 19, 1869, as an improved instrument for sharpening horseshoes, of a cutting pin of peculiar construction, whereby the said tool is adapted, when this cutter is applied in substitution of the cutter and jaw, is used for sharpening horseshoes, to cut off the ends of bolts with great facility. ”

“ When a tool of this kind is to be used on iron, steel, or copper, and not upon brass, the front face of the teeth may be given rake by cutting the grooves at an angle, as in Fig. 1109.
Boring Tools for Lathe Work.—The principal object in forming a boring tool to be held in a slide rest is to have the body of the tool as large as can be conveniently got into the size of the hole to be bored; hence the cutting edge should not stand above the level of the top of the steel. ”

“ There will be many men who will move one against another, holding in their hands a cutting tool. But these will not do each other any injury beyond tiring each other; for, when one pushes forward the other will draw back. But woe to him who comes between them! For he will end by being cut in pieces. ”

“ In any event springing away from its cut, resisting it until forced to cut, and then cutting deeper than should be, so that on a finished surface it is often apparent to the eye where the cutter began and left off. When, however, the radial faces are operated upon by a slide rest, as in the Sellers machine, the tool is more firmly held, and may be fed radially to the cut, producing true faces, and saving a great deal of time in making the cylinder cover joints, as well as in the boring and facing operations. ”

“ They are careless and in haste, and as a consequence they burn the steel or fail to work it sufficiently, and the result is a useless tool.
The steel may be of the very best quality, however, and well forged, and yet the knife may fail from being badly tempered—too soft or too hard. If too soft, the edge is soon dulled; the knife requires to be frequently honed, and the time wasted in keeping it in order is a serious drawback. If too hard, it is impossible to give it a keen edge, for the metal crumbles away as soon as it is honed or stropped very thin, and the edge becomes ragged and dull. ”

“ The knife that fulfils the specifications given elsewhere furnishes the second. And third, the man whose standard of work is high, who is conscientious in following his instructions, who is big enough and broad enough to understand how important his position is, and how necessary, therefore, it is for him to coöperate with every other department in a friendly and intelligent manner, completes the tripod that can stand up successfully under any job.
A cutting machine is a sharp-edged tool and, therefore, dangerous when run by a careless or unskilled operator. ”

“ Therefore wherever a knife with a flat side is used, no attempt should ever be made to grind this flat side on the hone. Such an attempt will almost always result in an edge so irregular that it will be almost impossible to cut a good section with it. But if the under side of the knife be left truly flat, we will have the very best tool that can be had for use with the microtome. ”