Edge tool

“ The whole secret of the skillful and successful use of this valuable tool lies in giving it the proper inclination to the work. It is shown in Fig. 1344, at e, in the proper position for taking a cut from right to left, and at f in position for taking a cut from left to right. The face of the tool lying on the work must be tilted over, for e as denoted by line a, and for f as denoted by the line b, the tilt being only sufficient to permit the edge to cut. If tilted too much it will dig into the work; if not tilted, the edge will not meet the work, and therefore cannot cut. ”

“ Portable tool chest.
All the small tools can be conveniently packed and carried in a leather or canvas hold-all. This is merely a long strip of either canvas or leather, with longitudinal bands sewn on the inside. The tools are arranged side by side under these, and then rolled up and tied carefully together with a wide tape string. All the edge tools should be tempered or let down to meet the file test, ground and set, before being finally packed. ”

“ But in tools driven by power, and therefore accurately guided in their line of motion, it is preferable to let the bottom face clear the work surface, save at the extreme cutting edge. The front face of the wedge or tool is that which mainly determines its keenness, as may be seen from Fig. 2180, in which we have the wedge or tool differently placed with relation to the work, that in position a obviously being the keenest and less liable to break from the strain of the cutting process. ”

“ 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. ”

“ Thus, in Fig. 2179 we have placed the bottom face at an angle of 80° to the line of tool motion, which is denoted by the arrow, and we at once perceive its weakness. If the angle of the top face to the line of tool motion is determined upon, we may therefore obtain the strongest cutting edge in a hand-moved tool by causing the bottom angle to lie flat upon the work surface. ”

“ The feather-edge breaks off when the tool is put to work, or when it is applied to an oil-stone, leaving a flat place instead of a sharp cutting edge. In well-hardened and massive tools, such as the majority of lathe tools, the amount of feather-edge is very small and of little moment, but in thin tapered edges, even in well-hardened tools, it is a matter of importance. ”

“ When the pressure between the tool and the work is sufficient, from the proportions of the work, to cause the work to spring or bend, the length of acting cutting edge on the tool should be reduced.
As the diameter and rigidity of the work increases, the length of tool cutting edge may increase. ”

“ 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. ”

“ 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. ”

“ If the work curves are sufficiently large, and the same is sufficiently rigid that a slide rest tool may be used, the length of cutting edge may be increased, so that under very favorable conditions of rigidity the tool edge may cut along its whole length without inducing either jarring or chattering, but the best results will always be obtained when with a broad cutting edge the tool is of the spring tool form shown in Fig. ”

“ To produce filed work thus true, all that is necessary is to set the cutting edge of the finishing tool at the horizontal centre of the work, properly adjust the live spindle of the lathe for fit to its bearings, adjust the slides of the slide rest so that there is no lost motion, and follow the rules already given with reference to the shape of the tool cutting edge, employing a cutting speed not so fast as to dull the tool before it has finished its cut, using a fine feed except in the case of cast iron, as already explained. ”

“ Original Specification.
'My machine is extremely simple, and consists of a head or standard carrying a tool-holder holding a tool for setting or burnishing the edges of the soles of boots and shoes, and a finger-rest to aid the workman in holding the edge up to the tool. 'The workman presses the edge up against the tool, and gradually moves the shoe so as to bring all parts of the edge to its action, steadying the shoe by the aid of the finger-rest, D, especially when burnishing the corners of the toes. ”

“ Tools for certain classes of work, such as thread tools, or those for turning brass or chilled iron, are ground flat on top, that is, without back or side slope.
Clearance for the Cutting Edge.—In order that the cutting edge may work without interference, it must have clearance; that is, the flank f (Fig. 10) must be ground to a certain angle α so that it will not rub against the work and prevent the cutting edge from entering the metal. This clearance should be just enough to permit the tool to cut freely. A clearance angle of eight or ten degrees is about right for lathe turning tools. ”

“ The wire is the edge or burr which bends or turns over at the extreme edge of the tool, in consequence of that extreme edge giving way to the pressure of the abrading tool, be it a grindstone or an oilstone. ”

“ The tool, in ordinary machines of this kind, is fixed so that it cuts only in one direction, as the plate is drawn against its edge or point, which is raised to allow of the backward motion of the plate. ”

“ In whetting, increase the pressure on the edges alternately so as to turn up a heavier feather edge there than in the middle, thus rounding the whole end very slightly. This feather edge may be removed in the usual manner.
57. To Tell Whether a Tool is Sharp or Not. —Examine the cutting edge, holding the tool toward the light. If the tool is dull, the cutting edge will appear as [64] a white line, the broader the line the blunter the edge. Fig. 107 A. If the tool is sharp, no white line can be seen. Fig. 107 B.
Fig. ”

“ A better way—the method a mechanic would use—is to test the edge by drawing the thumb along it lightly. Fig. 108. If the tool is sharp one can feel the edge “taking hold.” If dull, the thumb will slide along the edge as it would along the back of a knife blade. ”

“ The amount of feed per revolution of the work should always be less than the width of the cutting edge as otherwise ridges will be left on the turned surface. The offset tools G and H are for finishing exterior and interior cylindrical surfaces. These tools also have both vertical and horizontal cutting edges and are sometimes used for first finishing a cylindrical and then a horizontal surface, or vice versa. Tool I is adapted to such work as cutting packing-ring grooves in engine pistons, forming square or rectangular grooves, and similar work. ”

“ The scraping takes off only a dust. If too strong depressions may be made deeper than before, and requiring the reduction of the entire surface. The superiority of the modern tool is now especially shown. By lowering the angle of the tool, the workman presents the slightly curved edge to the surface in a position as nearly parallel with it as he desires. ”

“ The essential features are, to have a rigid support against which the tool may be pushed by the revolving stone, to hold the tool at a fixed angle which may be adjusted, and to press the tool against the stone with considerable pressure. The wheel should revolve toward the edge which is being ground, for two reasons. It is easier to hold the tool steadily thus, and the danger of producing a wire edge is lessened. ”

“ Cutting or trimming the edge of the sole and burnishing the same with a tool have been practiced time out of mind in the art of making shoes; but within the past 50 years there has grown up a separate business in the manufacture of edge trimmers and edge burnishers, the outline of each tool corresponding with that of the other. The machine shown and described in the Helms patent in suit consists of a reciprocating tool-holder, carrying an ordinary burnishing tool, and an adjustable finger-rest or hook, ht front surface of which projects just below the tool. ”

“ It is obvious also that the flat place being turned uppermost, will facilitate the use of the file on work of smaller diameter than the lathe centre, and that placed in the position shown in the cut, it will permit a squaring tool to pass clear down to the centre and avoid leaving the projecting burr which is left when the tool cannot pass clear down the face to the edge of the countersink of the work centre. ”

“ Upon the edge of a tool that last receives the action of the stone there is formed what is termed a feather-edge, which consists of a fine web of metal that bends as the tool is ground, and does not become detached from the tool in the grinding. The amount or length of this feather-edge increases as the work is thinner, and is greater in soft than in hardened steel. It also increases as the tool or piece is pressed more firmly to the stone.
To prevent its formation on such tools as plane blades or others having thin edges, the tool is held as at g in Fig. ”

“ We do this, and soon get our edge; the bright rim has disappeared, but we have done an unwise thing, and have not saved much time, because we have begun to make a rounded edge, which, if carried a little farther, will make the tool useless until it is reground. There is no help for it: time must be spent and trouble taken in sharpening tools; with method and care there need be very little grinding, unless tools are actually broken.
To resume our lesson in tool-sharpening: we can not do much carving with one chisel, so we shall now take up gouge No. ”

“ In 1864 Stephen Williams in the specifications of his patent 43,360 stated:
I denominate my improvement the "universal smoothing plane," because it belongs to that variety of planes in which the face is made changeable, so that it may be conveniently adapted to the planing of curved as well as straight surfaces. By the use of my improvement surfaces that are convex, concave, or straight may be easily worked, the face of the tool being readily changed from one form to another to suit the surface to which it is to be applied. ”