Files and Rasps.--- These comprise a class of tools having surfaces covered with sharp edged furrows or teeth; which are employed for removing particles of wood, metal or other ma terial by the process of abrasion or the cutting action of a multitude of fine points. They are made in a vast number of shapes and sizes and of various degrees of fineness or coarseness to adapt them to various kinds of work and materials. A file differs from a rasp in that its furrows or teeth are made by straight cuts in flicted on its surface by a reciprocating chisel before the metal is hardened, either in a series of single cuts or crossed cuts, while the teeth of a rasp are a number of isolated projections raised on its surface by the pyramidal end of a triangular punch. See FILES AND FILE MAK ING in this Encyclopedia.
Edge Tools comprise the various forms of chisels and gouges, the planes and a miscel laneous assortment of spokeshaves or smooth ing tools and various appliances such as grind stones, emery wheels and oilstones, used for maintaining a sharp cutting-edge on the various tools.
Chisels and The essential princi ple of these types of cutting tools is that of the wedge. The chisel in its simplest form practically constitutes the slice of an axe, hut as its action or movement is the result of the force applied to it by the blows of a mallet or hammer, the eye of the axe is replaced by a suitable device for receiving the blows. When the element of thrust enters into the operation of a chisel, as in the cases where it is used by the simple pressure of the hand, its action passes into that of the plane iron. Chisels are specifically defined as "chipping," "cross-cut," "firmer," "pairing" and "mortise" chisels. The firmer chisels are the ordinary short chisels used by wood-workers and are so designated in order to distinguish them from the paring chisels which are usually about twice the length of the firmer tools and are almost exclusively used by patternmakers. Paring chisels are sel dom driven with the mallet, but arc actuated by hand pressure alone. They are made in width ranging from one-fourth inch to two inches. The mortise chisel is a stout wood workers' chisel which is driven with a mallet and used for cutting mortises where percussion and leverage are rendered necessary. The gouges are forms of paring and firmer chisels which have curved cross-sections. The cutting edge of the paring gouge is formed by grinding its inner face and that of the firmer gouge by grinding its outer face. Gouges vary in width from one-eighth inch to two inches. The par ing gouge differs from the ordinary firmer gouge in its increased length. It is never driven with the mallet, but is applied with a thrusting motion of the hand and is used chiefly by pat ternmakers for cutting the various curved out lines of their work. It will be observed, that as a rule, the chisel cannot be satisfactorily used over a surface wider than itself, and, therefore, the gouge was devised in order to obtain a tool of greater utility for that pur pose. In practice this advantage is partially realized, but there still remains quite a tendency on the part of the gouge to follow the grain of the wood instead of cutting through the fibres at a very slight inclination. All gouges are held and used in the same way as a paring chisel, but if any occasion demands the driving of a gouge with a mallet, it should always be held in a perpendicular position.
Spokeshaves or Drawing Knives are es sentially two-handed blades which can only be used by being pulled toward the operator. The general form consists of a long, narrow, chisel edged blade the ends of which are attached to two handles which stand at right angles to the blade. These handles are of wood and the "tangs" into which the ends of the blade are prolonged are bent around at right angles to the blade and pass right through the handles and are riveted over brass plates at their ends, in order to prevent the blade from being drawn out of the handles when it is drawn toward the workman against the resistance of the wood.
These tools are used for cutting thick and heavy chips off the rough edges of boards so as to decrease the amount of the work required in the planing operations and they are also used by patternmakers for the cutting of sweeping curves or "sweeps" in work where great ac curacy is not essential. Router types are pro vided with cutters of varying forms and are effectively used for chamfering, rabbeting and other similar purposes.
In its simplest form the plane con sists of a chisel-shaped plane-iron, so-called, though made of steel, placed at an angle in a °stock* or box of wood or metal in such a way that the cutting edge projects slightly through the bottom of the box. It derives its value from the guidance imparted to the cut ting edge by the sole or bottom of the box. The plane is operated by being pushed forward, over the surface of the material being worked, so that the cutting edge bites into the fibre and removes a thin shaving which slides up ward along the upper side of the plane-iron and is thus discharged. from the hollow of ihe box. The depth of the cut or the thickness of the shaving removed may be regulated by rais ing or lowering the plane-iron, which is usually held in place by means of a wedge or by a screw, and is, therefore, capable of being ad justed. The plane-irons are made both single and double. In the latter case, the back-iron is introduced for the purpose of brealcing the shaving sa as to reduce the amount of cumu lative indrawing force due to the continuity of the fibre of a long shaving. Planes in which double plane-irons are used are called "built up)) planes. There are at least a hundred differ ent ldnds of planes in use at the present time, but all of them may be grouped into three gen eral classes— the °jack-planes,* the °trying planes° and the °smoothing-planes.* The jack plane is the first plane used for roughing down the timber received from the hands of the sawyer or from the saw-mill. The cutting-edge of its plane-iron is more curved than those of the other planes and consequently talces coarser and narrower shavings. The trying-plane is used after the jack-plane for producing the great est accuracy attainable in the surfacing of wood by hand. It is usually about 22 inches in length and carries a plane-iron about two and one half inches in width. The cutting-edge is sharp ened perfectly straight transversely, and this, combined with the length of the plane, enables the workman to produce very true surfaces by its use, The smoothing-plane is a small plane used for imparting a smooth finish to surfaces in work where extreme accuracy is not es sential. It is made about eight inches in length and is designed to carry plane-irons ranging from one and three-fourths to two and one f ourth inches in width. Some of the more useful and important special forms of planes are the °rabbet)) or °rabbeting') plane, em ployed for making window frames and other similar work in which a rabbet or recess is required to be cut for the reception .of the edges of a glass plate or other matenal; the "plow,* employed for cutting a deep groove along the edge of a board for the reception of a corresponding tongue formed along the edge of an adjoining board, and the °stop-chamfer* plane, employed for cutting any chamfer or bevel-edge ranging from one-eighth inch to one and one-half inches in size, with a constant angle.