35. Back Saw

The back saw is a cross-cut saw with very fine teeth. It is intended for fine and accurate sawing. The saw blade is very thin and this is reenforced by an iron strip extending along the back of the saw. The blade is uniform in width and is from 8 to 14 inches in length.

Fig. 61. Backsaw, a, blade; b, handle; c, teeth; d, tip; e, heel; f, back.

36. Bracket Saw

A bracket saw is a saw constructed in such a way that it can be used in sawing curves in thin woods. It is a very valuable tool in manual training work, for many of the projects are made up of curved designs. The blades are made in different lengths and sizes from 3 to 5 inches for different thicknesses of wood.

Fig. 62. Bracket saw. a, frame; b, blade; c, handle.

37. Hack Saw

A hack saw is constructed very much like a bracket saw except that it is heavier. It is used in sawing metals. The blades have about fourteen teeth to the inch and are from 6 to 12 inches in length. The one shown in Fig. 63 is adjustable, taking blades of different lengths.

Fig. 63. Hack saw. a, frame; b, handle; c, adjustable back ; d, blade.

38. Miter Box

A miter box is a device for holding wood while it is being sawed at an angle. Such a device is very useful in the making of picture frame joints or miter joints. Fig. 65 shows an improved New Langdon miter box which can be used in cutting any angle from a right angle to 45 degrees. This box has several adjustments which are valuable. Fig. 64 is a cut of a box that can be made in any shop. It should be made of some hard wood like beech or maple. A cross-cut or a back saw can be used in sawing by letting the saw run in the cuts made in the box. A miter box should never be used in doing work that is intended to develop skill in sawing. Fig. 66 shows a miter planer which is used in planing end wood, or in planing at any angle.

Fig. 64. Miter box.

Fig. 65. Improved new Langdon miter box.

Fig. 66. Rogers miter planer.

39. Files

A file is an instrument made of steel, having its surfaces covered with sharp-edged furrows or teeth. The furrows are made by straight parallel cuts in the steel. For names and illustrations of cuts see Plate A, Fig. 67. As to the coarseness or fineness of files, they are classified as rough, middle cut, bastard, second cut, smooth, and superfine or dead-smooth. As to the kind and coarseness of cuts and the shapes and sizes of files, many combinations are made, giving a great variety of files. The File Manufacturers' Association of the United States quote more than 3000 different files and wood rasps alone. The work to be done must determine the kind of file to use. A new file should be used lightly at first, until the thin sharp edges are worn off, after which a heavier pressure may be applied. In filing high-tempered steel the finer grades of files, called second cut, should be used. In using a file a steady stroke with strong pressure is most effective.

William T. Nicholson, founder of the Nicholson File Company.

Fig. 67. Files anil rasps. a, hand smooth file; b, taper saw file; c, half-round wood rasp.

Double cut coarse.

Rasp, bastard.

Double cut bastard.

Single rut bastard.

Rasp, second cut.

Dbl. cut second cut.

Sing. cut sec. cut.

Rasp, smooth.

Double cut smooth.

Single cut smooth.

Plate A, Fig. 67.

40. Wood Rasps

A wood rasp is a kind of file used in cutting down rough edges of wood. It differs from a file in that the teeth of a rasp are coarse, single teeth, raised from the bar of steel by the pyramidal end of a triangular punch struck obliquely. The wood rasp is a tool whose use should not be encouraged very much in manual training work, and when it is used it should never take the place of an edged tool.

Fig. 68. File cleaner.

41. File Cleaner

A file, like every other tool, should be kept clean. For this purpose a file cleaner (Fig. 68) is used. It is a wire brush made of the best grade of fine steel wire.