They consist of a flat or concave blade made of steel, the cutting end of which is cut straight across and sharpened to an edge, and the other wrought into a four-sided tang, which is set into a wooden handle. The tool in working is driven into the wood either by the pressure of the hand, or by-blows from a mallet. In order that the handle may not slip, or twist round when grasped, it is generally made with four sides, greater in breadth than in thickness, and with the broader sides rounded.* To keep the handle from splitting under violent pressure, the base of the tang is furnished with a shoulder, on which the handle rests.
Parts of a chisel, etc.
These tools vary greatly in size both as regards length and breadth. The latter dimension determines the dimensions of the edge. The broadest tools are generally also the longest.
In order to be able to execute all the different kinds of exercises which occur, it is necessary to have a complete set of each description of tools. There are usually 12 in a set, all of different breadths. Tools of this kind are classified according to the different shapes of the blade and edge, and the different methods of sharpening as follows: -
Fig. 49. Firmer Chisel 1/4.
A. Blade and handle.
B. Blade showing a face and edge.
C. Blade, c. shoulder, d. tang.
These tools have a straight edge ground on one side.
1. The Firmer Chisel (Fig. 49). The breadth of the blade, which varies from 11/2 inches to 1/4 inch, is generally much greater than its thickness. The face of the edge in all such tools forms with the front side an anode of 200 to 25°.
The firmer chisel is used in paring plane or convex surfaces; in mortising, when it often does duty instead of the mortise chisel; in curved work ; in facing off; and, generally speaking, in all cases where no other tool can be made use of with advantage.
* English handles are generally turned in boxwood or beech. - Tbs.
2. The Mortise-chisel (Fig. 50). The thickness of the blade generally exceeds its breadth, which varies from $ inch to 1 inch. The front face of the blade is always a little broader than the back.
The mortise-chisel is used for mortising; and, whenever possible, a blade of the same breadth as the mortise to be made should be selected. The great thickness of the tool enables its sides to act with steady force upon the sides of the mortise, and makes accurate execution of the operation much easier. It is driven into the wood by blows from a mallet. The angle of the edge is the same as in the firmer chisel.
These tools have a curved edge.
The blade of the gouge is concave. The face of the edge may either be (a) ground from within outwards, in which case the edge will lie upon the inner or concave side, or (b) in the reverse way, when the edge will lie upon the outer or convex side.
Gouges ground in the first mentioned manner are used in the formation of grooves or bowl-shaped depressions. Those ground in the other way are used chiefly in perpendicular paring to produce concave and cylindrical surfaces.
Fig 50. Mortise-chisel. 1/4.
B. shows breadth and angle of the edge.
Fig. 51. Gouge 1/4.
A. with edge on the inner side.
B. with edge on the outer side.
The breadth of the gouge varies from 1/4 inch to 11/2 inches, and the curve of the edge may include from one-tenth to one-half of a circle, or 36° to 180°. All the gouges in one set should have the same curve in the edge. The gouge is driven into the wood by the hand, or in the case of gouges of large size, by the mallet.
3. The Spoon Gouge and the Spoon Iron.
Ordinary gouges are often used in forming the bowls of spoons and similar articles, but the tools specially adapted, and best for the purpose, are the spoon gouge and spoon iron. The larger illustration (Fig. 52) shows the spoon gouge. In construction, and in the way it is used, it somewhat resembles A (Fig. 51); but it diners from it in having the blade curved lengthwise, to facilitate the work of hollowing out.
The spoon iron is different in form. It is shown in the smaller illustration (Fig. 52), and resembles a knife with a lancet-shaped blade, with two edges, curved like a bow, and tapering to a point at the end. It is worked with both hands, and cuts to either side.
4. Carving Tools.
A number of tools, more or less like the preceding, are used in wood-carving. Some of these carving tools are flat, with rectangular edges; others are oblique to the direction of their length, with a bevelled edge on both sides; others are concave, with a circular edge, or have two edges meeting in a point. They are straight in some cases; in others, curved.
As only a few of these tools are used in slojd carpentry, to any extent worth mentioning, no description of them is given; but those in most common use, with their names, are shown in Fie. 53. The full size of the edge is eaven in the outline beside the representation of each tool.
Fig. 52. Spoon Gouge and Spoon Iron. 1/4.
Fig. 53. Carving Tools. 1/4.