HAND TOOLS. Within the limits of the present article it would be impossible to describe even the majority of the instruments which may come under this designation, including as it does (in its popular if not in its technical sense) the whole of the appliances used by the handicraftsman in the treatment, by means of his muscular energy, of the natural substances used in the arts and manufactures, —whether in the preliminary operations of setting-out and measuring his materials, in reducing his work to the required form by cutting tools or otherwise, in gauging it and testing its accuracy, or in duly securing it whilst being thus treated. Omitting therefore the large but by no means unimportant class of measuring and gauging instruments, straight edges, templates, &c, we will confine our attention to examples of those in the use of which an actual expenditure of force is necessary. According to the structure and other proper-ties of the materials to be treated by them, these act'almost without exception either by impact, by pressure, or by cutting, the last being effected sometimes with impact and sometimes with pressure. The principal tools acting purely by impact are noticed under HAMMER (q. v.). Those which depend solely on pressure are for the most part of an auxiliary character only, and their consideration will be deferred till we have glanced at a few of the much more numerous and more important class known as cutting or edge tools.
It should be observed that the term " cutting" is applied to processes which have but little in common, the great differences of structure in the materials operated upon demanding equally great differences in the modes of effecting the desired end, which is in almost all cases the forcible separation of their particles in some regular and definite manner. If we regard, for example, the action of a sharp knife upon a piece of chalk as one of true cutting,—i.e., the separation of its particles by the forcible insertion of ti wedge-like blade of superior hardness to itself,—we shall find that in by far the larger proportion of instances this simple action is rendered complicated, either through the substance under treatment being insufficiently compact to afford in itself the necessary resistance, or through its want of homogeneity causing a tendency in it to part more readily in some directions than in others. Thus all kinds of wood and the generality of both vegetable and animal substances, being cellular or fibrous in their structure, offer so much less resistance in a direction parallel to their fibres than in one transverse to them that in the former case many of them may be parted by fissure without any true cutting at all. So also with crystalline materials—as is beautifully exemplified by the diamond, which lends itself to cleavage in certain planes in the most perfect manner, though the steel chisel which is employed for the process is very much inferior in hardness to itself. Metals also are frequently not homogeneous ; indeed they are sometimes said to be fibrous in structure, but it is only to a very limited extent, if at all, that they are so, and their great natural tenacity even then prevents the separation of their particles except by a true cutting process. Lastly, some stones and minerals, such as sandstones, are said to be cut, though they are formed of material consider-ably harder than the tools which are used upon them, the faet being that their hard particles are not cut at all, but are merely separated from one another when the cementing material which holds them together is compelled to give way.
I. Cutting or Edge Tools.—These, the term "cutting" being thus quaiified, are mainly of two classes—(i.) cutting tools used with impact, and (ii.) cutting tools used mainly with pressure. These again may be subdivided into tools used (1) for wood and soft materials, (2) for metal, and (3) for stone and hard substances.
i. 1.— Wood-tools cutting by impact comprise all the varieties of axes and adzes, such as the ordinary English pattern of carpenter's a removed is so small that its tranverse strength is inferior to the iateral tenacity of the fibres. So also do chisels and gouges when driven by blows from a hammer or mallet. The ordinary mortice chisel (e, fig. 2) and the socket chisel (/) are specially adapted for being used in this way.
2. In the case of metals their hardness in general almost precludes the possibility of employing upon them any tools corresponding to the above. If we except a few special tools such as plumbers' knives, &c., chisels will be found to be almost the sole representatives of this class. A blacksmith's chisel (g) held in a hazel withe, and used for hot iron, and some common forms of chisel for chipping it cold are shown in fig. 2, these being known as a chipping chisel (h), a cross-cut (j), a diamond point (k), and a round-nose (Z).
3. Tools of this class for stone also consist chiefly of chisels, the mason's chisel (TO) varying greatly in width of edge according to the variety of stone and the depth of the cut to be taken. Frequently they are brought quite to a point like the mason's pick, when they cease to be cutting tools from our point of view. The jumper (n), employed for rock drilling, with which the hole is produced by means of successive cuts radiating in all directions from its centre, which are delivered with the impact due either to its own weight or to the blows of a hammer on its outer end, is also a form of chisel.
ii. Edge tools operating by pressure.—Of this class the ordinary clasp-knife is perhaps the best known example. A sharp knife serves well for showing the different kinds of treatment by cutting or by fissure to which any particular wood or other moderately soft material is capable of submitting itself. The "thickness" of the cutting edge, or in other words, the angle which the inter-secting planes wdiich include it form with one another, the degree of smoothness or roughness of edge which best effects the clean division or separation of the fibres, and the possibility or other-wise of producing a smooth surface by "scraping," can all to a great extent be judged of with the aid of a knife. And the sub-ject is by no means an unimportant one. Consideration of the action which takes place at the edge of a cutting-tool, and the strain which this action produces on particular portions of it are frequently of service in enabling us successfully to meet the special cases which arise in practice, and may sometimes guide us towards remedying the defective action of the hand-tools in use for ordinary work. America has long taken the lead in originating thoughtful improve-ments of this kind, and the result is apparent in the rapid manner in which the use of edge tools and appliances of American patterns is now everywhere extending.
1. In fig. 3 are shown a few of the ordinary English wood-tools. They include the firmer chisel (o) used by carpenters, and a carver's chisel ip) and gouge (q). A wood-engraver's scooper (r) and knife (s) are examples of special tools, being intended only for cutting hard wood in a direction transverse to the grain, cross-cut blocks of box-wood being alone used for the finer kinds of wood-engravings. The spoke-shave (t) affords a good example of what has just been said as to the result obtainable by a well-directed effort towards the improvement of an old established hand tool. In the form figured (t), which is the ordinary one in use in England, the blade or '' iron" is rather complicated in shape and is not very easy to sharpen;
FIG. 2.—Chisels.
is a particularly rapid and efficient tool in skilful hands. All these when used in the direction of the grain of the wood act by cleaving rather than by cutting, except when the thickness of the chip each successive sharpening moreover impairs the efficiency of the tool by widening the "mouth," the unequal wear of the wooden sole, which very speedily takes place, having also a similar effect. Thus three essential conditions of a good cutting-tool, viz., constant maintenance of its proper action, durability of the parts exposed to wear, and facility in sharpening are all unfulfilled. On the othe: hand those manufactured in America fulfil them admirably; iron is substituted for wood as the material for the sole and handle, and the blade, which is merely a piece of flat steel, is firmly held in its place by a set screw, half a turn of which at once releases it.
Planes are to be met with in great variety, the most usual for ordinary carpentry being the jack plane (u), the trying plane, and the smoothing plane (v). Of these the first is used for tak-ing off the rough, or for reducing the thickness of a board ; the second, which resembles it, except in being of much greater length, for correcting inequalities of the surface ; and the third, as its name implies, for the final smoothing. Planing being chiefly performed in the direction of the grain of the wood, a smooth surface can only be obtained when its fibres are cut instead of being allowed to separate from one another by cleavage, the ten-dency to which, in soft woods more especially, must therefore be carefully resisted. With this object the planes above mentioned, and many others also, are provided with what is called a '' double iron," an inverted blade or "iron" being securely attached to the upper side of the cutting iron, with its edge at a short distance only from the cutting edge. This causes the shaving to be continually broken transversely, and so prevents the fibres of which it is com-posed from tearing up those in advance of the cut. The width of the "mouth" or space between the cutting edge and the portion of the plane stock in front of it is also kept as small as possible in planes intended for smoothing, so as to increase to the utmost their breaking action by supporting the as yet undisturbed fibres in advance of the cutting edge. Wear of the mouth is sometimes pre-vented by letting in a metal plate or by forming the stock entirely of iron or steel. Planes of great length, which are known as jointers, are used for some purposes, coopers' planes of this kind being sometimes over 6 feet long.
The use of moulding planes (w) is indicated by their name. Each is adapted only for producing one particular pattern of mould-ing. Hollows and rounds resemble them, but have the cross section of their soles simply concave and convex respectively. For planing work which is hollowed or rounded in the direction of its length compass planes are employed, each of which, as ordinarily made, cannot deviate much from its own particular curvature. American ingenuity has here agdn stepped in, andhas got over this objection by making the sole of a springy plate of steel, wdiich can be ad-justed to any curve either convex or concave within very wide limits, so that this one tool takes the place of an entire set of ordi-nary compass planes. Ploughs are somewhat complicated planes which are used for forming grooves of various widths, depths, and distances from the edge of the work.
The "pitch" of a plane is the angle at which the blade or iron is inclined to the sole, and the inclination is greater in hard-wood than in soft-wood planes. Some of the former, indeed, have their irons so nearly erect that their action is what would ordinarily be de-scribed as scraping and not cutting—a difference which appears to be uudefinable, and to be due to the structure of the materials which can be so treated, and not, as has been suggested, to any peculiarity in the form of the cutting edge. The action of a razor in shaving seems to favour this viewr, the sections of hair thus obtained being seen under the microscope to be beautifully cleanly sliced, though the blade is applied at a great angle to the plane of the cut.
The following may be taken as good examples of saws—the hand saw (x), the rip saw and half-rip saw, which differ from it only in size and size of tooth, and the dovetail saw and tenon saw (y), of which the first three all have sufficient stiffness of blade to resist the force exerted in using them, and the last two are thin and unable to do this without the support of the iron or brass " back," which of course limits the depth to which a cut can be made with them. Pit saws and cross cut saws are the largest representatives of saws used by hand, being employed for large work, such as cut-ting timber in the log, and worked generally by two men. Frame saws of all sizes, from those of 8 feet or 10 feet used by pit sawyers down to the fret saws of but a few inches in length and scarcely thicker or wider than a horse hair, and compass saws, for cutting out curves, must also here be mentioned amongst hand-saws, though technically they are not included in the term.
In fig, 4 are some diagrams of saw teeth,—A being the usual form for all the smaller kinds that are used single-handed, which is varied however as to size and also as to the angle at which the "three square" file used in bringing the teeth to an edge is applied, while B is the gullet-tooth, for pit saws working with the grain of the wood, and C the ordinary cross-cut tooth, for transverse cuts. It is evident that a saw tooth which is well adapted for producing a clean cut in one of these directions would be ill-adapted fordoing so in the other, at least in the case of the softer kinds of timber,—for in sawing with the grain the readiness and the uniformity with
[vvVVVVVv
« B C D
FIG. 4.—Varieties of saw teeth.
which the short section of fibres sliced off by each tooth parts from the fibres by its side (owing to their slight lateral cohesion already alluded to) assists in the operation, and a fairly clean cut results. But in cross-cutting special provision is required for cleanly divid-ing the fibres at each side of the cut, after which the removal of the intervening fragments can be accomplished readily by cleavage rather than by cutting. The rationale of the gullet-tooth (B) is thus clear, the keen chisel-like edges of the teeth being well adapted for slicing the fibres of the wood transversely, and for this it leaves little to be desired. The cross-cut tooth (C), consisting as it does of a, series of lancet-lite points acting alternately at each side of the cut, divides the fibres, but has no proper provision for their after removal, and the hand saw tooth (A) is a sort of compromise between the two (at least if we neglect the rounded portion of the gullet-tooth, which does not affect its edge), so that it can be used either with the grain or across it, though not with the best possible results. The cross-cut tooth (D), on the other hand, provides both for the clean separation of the fibres and the removal of their fraGments.
The "set" of a saw is the slightly increased width given to its toothed edge by alternately bending the teeth towards the opposite sides of the blade; the extent to which this is done, or the width of the set (as it is called), therefore determines the amount of material which a saw wastes in forming its cut, the more perfect its action the smaller being the amount of set required to make it work freely, and the less the power expended in working it.
Some boring tools for wood are shown in fig. 5. The brad-awl (E) is adapted only for soft wood; the gimlet, either in its plain or its twisted form (F), has little to be said in its favour ; and the shell-auger (G) requires an expenditure of force altogether dis-proportionate to the results produced by it. The screw-auger is an improvement upon it, although this, as generally made, still leaves a good deal to be desired as regards consumption of power. But the wood-worker's main stand-by for boring is the stock or brace (H) and set of bits. Those ordinarily supplied for
FIG. 5.—Boring tools.
boring across the grain consists mainly of centre-bits (I) for the larger and quill bits for the smaller holes,—neither of which are thoroughly efficient tools,—also nose-bits (J), which resemble shell-augers and share their defects, for boring with the grain. The English wood-boring tools indeed offer a considerable field for im-provement. Imported substitutes for the above are already to be met with, amongst others being the twisted centre-bits, of which the stems resemble the twist drill referred to below, and the ex-panding centre-bits, both of which appear to be an advance in the right direction, though they have not as yet come largely into use.
2. Cutting tools for metal analogous to the foregoing are but few as regards surface work. Their chief characteristic—at least in the case of those used for the harder metals—is the greatly increased thickness of their edges. Files of various cross sections, lengths, and degrees of fineness of tooth, and scrapers (which are merely thick knife-edges, made not unfreqnently from worn-out files by sharpening them at the extremity), constitute almost the only edge tools at the disposal of the fitter or mechanic for finishing work that he has roughly surfaced with his chipping chisels. For boring he has drills of various sizes, too often of the antiquated pattern (K), which in boring deep holes cannot be kept straight, though the very superior twist drill (L) is now often to be met with. Countersinks, either of the flat (M), rose (1ST), or snail-horn pattern (0), are generally included with carpenters' sets of bits, for enlarging holes in metal work to receive the heads of screws. They are used with the wooden brace figured above. The smith's brace resembles it, but is all made of iron, and a heavy pressure is applied to its upper end by means of a screw. A ratchet brace (P) is a more powerful instrument, and carries in itself the screw for obtaining the requisite pressure. Small holes can be drilled under a light pressure with rapid rotation on the part of the drill, which is then generally of the form K, but sharpened from both sides, so as to form a knife-edge which oper-ates equally well in whichever direction the drill revolves. The drill bow, of wdiich the string takes one turn round a bobbin either on the stem of the drill itself or on its holder, is a ready means of obtaining a rapid reciprocating motion for this purpose, and is not yet superseded, though various ingenious substitutes have been devised. For enlarging holes throughout their length broaches or rimers are used ; these may be either simply half round or poly-gonal in section, or may have any desired number of longitudinal or spiral flutings, each of wdiich forms a cutting edge which removes successive portions from the sides of the hole to be enlarged. A parallel rimer with four flutings is shown at B, the square end when in use being inserted in a hole in the centre of a wrench, which affords the requisite leverage.
An internal screw thread is formed in an analogous manner by a tap, which bears on its surface the counterpart of the required thread, so that by successive cuts it produces a helical groove of the correct form and depth. Such a tap (S) is represented in the en-graving, together with a diagram of its cross section, showing the three cutting edges by which the screw thread is formed. Three such taps constitute a set for any one size of screw, the first being known as a taper, the second as an intermediate, and the third
Fig. 6.
as a plug-tap, this last being almost parallel throughout. By a reverse process with dies fixed in a stock (T, fig. 6) external screws are cut, the particular form shown being the improved pattern of Sir J. Whitworth, who has done much to correct the faults of the earlier screwing tools. Screw plates, however, some of which can-not be regarded as cutting tools at all, are still much used for small and fine screw threads.
Cutting pliers and cutting nippers (U) have a pair of knife edges so arranged as to work exactly opposite to one another,—the handles, on being tightly grasped, affording sufficient leverage for these edges to be forced to a short distance into the two opposite sides of a nail or wire, which, if of small diameter or of soft metal, can thus be cut asunder. Tube-cutters are an ingenious device which the extensive use of wrought-iron tubing for gasfitting has rendered necessary. They effect their object by cutting a groove round the tube to a sufficient depth to enable it to be fractured at the desired point.
3. Stone and hard materials cannot in general be treated by cutting tools simply with hand pressure, though some of the softer kinds of stone are carved with chisels used almost or altogether without impact, and are sawn with toothed saws resembling the cross-cut saws used for wood. Glaziers' diamonds were till recently the only tools for producing the peculiar "cut" requisite for starting the clean fracture by which sheet glass is divided, theirs, however, being a case of fissure rather than of true cutting. But of late years steel glass cutters have been introduced which act—as long as the sharp-ness of their edges is maintained—in a manner precisely similar. In one form of these glass cutters (V) a cast-iron handle carries at its extremity a small freely revolving wheel of carefully hardened steel, round the circumference of which is the cutting edge, which can be sharpened on an oilstone when necessary. The so-called cut is produced by simply running this with a light pressure over the sur-face of the glass. Diamonds, however, are used for cutting glass, stone, &c., by actually detaching their particles; writing diamonds and diamond drills have this kind of action.
II. Hand-tools without cutting action.—With the exception of hammers and a few tools which are dependent on impact,—such as cleaving wedges amongst wood tools, and embossing and similar punches amongst those for metal,—tools of this class play in general only a subsidiary part to some cutting or other process.
Amongst those used with pressure which cannot be considered as auxiliary may be instanced—draw-plates, with which wire is made by drawing it through holes of conical form and of successively smaller diameters till the required size or "gauge" is reached; and burnishers, wdrich reproduce on metals softer than themselves their own highly polished surfaces. Both of these act by inducing a flow of the metal under treatment for which, when it is not effected by impact, great force is required in proportion to the extent of the action. Metal shears and cutting punches of all kinds have been omitted till now, as their mode of operating cannot be regarded as true cutting from our point of view. It may be more correctly described as tearing, more or less completely localized according to circumstances. The ordinary sheet-metai shears (W) merely resemble very powerful scissors, and, their action being quite local, they serve well for dividing the plates or other thin sheets for which alone they are suitable. Block shears (X) act with additional leverage, and can consequently be used for rather thicker metal, the upper bow being replaced by a long straight handle, and the lower one by a stake which can be firmly fixed in a block of wood or otherwise. With these the tearing action begins to be apparent, though its imperfection is of no great importance with the thick-nesses of metal capable of being treated by any hand shears (for some tools of this class, which by hydraulic or other means accumulate the power of one man to a sufficient extent to operate on bars or plates of comparatively great substance, are machines rather than hand tools, and in their case the mere slowness of the operation produces better results than would otherwise be obtained). The same may be said of the various punches used in combination with dies or bolsters, as in the punching bear (Z), of which the action exactly resembles that of shears, the punch taking the place of the upper blade, and the bolster that of the lower one.
Of subsidiary tools (figs. 7) the vice is an absolute essential for the generality of metal workers. The ordinary tail-vice (a) used by mechanics has not yet been largely superseded, though many ingenious arrangements have been devised for remedying its main defect, viz., the want of parallelism in the movement of the jaws. The English parallel vice (fl) has not this objection, but its construction is not good mechanically, and it is but little used except for small work. In some patterns of vice, jaws are provided wdth a horizontal adjustment so as to grip tapering or other irregu-lar forms, and in others the whole body of the'vice can be swivelled
f\ 5
Fig. 7.
either vertically or horizontally. Hand-vices are used in the manner implied by their name, without being attached to a bench like the foregoing. An ingenious form of hand-vice (7) is shown in fig. 7. The screw wrench (8), which is used for turning nuts, &o., of various sizes has of late been deservedly the subject of various improvements in which weight is sought to be saved without sacrifice of strength ; and the shifting spanner, of which the duty is the same, has led to the exercise of much ingenuity without any perfectly satisfactory solution of the problem how it may best be constructed. The merit and simplicity of the ordinary screw-driver, on the other hand, are well known.
Instances of tools which afford a powerful grip by simple means are the blacksmith's tongs (e), the vice-chop tongs (Q, the pliers (n), and the pincers ($). A very powerful modification of the last-mentioned tool has lately been introduced into use under the name of the nail-puller (1). With this ingenious instrument very largely increased leverage is obtained, and the pull is given in a direction much more advantageous to the attainment of the desired object. (C. P. B. S.)