The Handyman's Book of Tools, Materials, and Processes Employed in Woodworking. Paul N. Hasluck
href="#ulink_5cf2aa93-e0b8-57f2-9be0-6fb4e1aeced0">Fig. 256 and Fig. 257, but the dotted lines in the latter figure show that the angle of the tooth is shaped correctly. By “hook” is meant the lead or rake the fronts of teeth have—that is, the distance the point of tooth overhangs the bottom of front of tooth. It will be noticed that in Fig. 258 the teeth are filed a little hollow in front- and at the back. This is a great mistake, and several reasons could be assigned. One reason is that a correct angle cannot be determined (see dotted lines in Fig. 258). In shaping the teeth of a tenon saw it is wrong to make their cutting faces upright as shown in Fig. 253. This causes the saw to bind in the wood at the forward stroke. The front edges of the teeth being vertical, they bite too much. For a tenon saw to act freely, the front edges of the teeth should make angles of about 80°. There are several peculiar forms of American teeth, though they are no great improvement on the ordinary saw teeth. Figs. 259 and 260 represent American cross-cut saw teeth. Fig. 259 is termed the regulating tooth. By filing the centre tooth to an acute angle, it will be suitable for cutting soft wood; for cutting hard wood the teeth should be filed to a more obtuse angle. Fig. 260 is termed the lightened tooth. The sharpening should be much the same as Fig. 259 for different kinds of wood. A tooth that is least difficult to sharpen when filed to its proper cutting angle is found to be the best form of tooth. For general cross-cutting the peg tooth (Fig. 261) is recommended. This is suitable for a soft wood cross-cut saw with two handles. The faces of this tooth, which cuts both ways, should be filed to an angle of 50°, the space between being 130°. When this form of tooth is used in cutting hard wood it should be filed to a more obtuse angle. If a saw is to cross-cut hard wood only, the gullet or one-way cross-cut tooth (Fig. 256) is recommended. This tooth will be found easy to sharpen, and, if properly sharpened, will cut as fast as any tooth, and faster than most. The more upright the front of teeth (Fig. 257) the faster the cut, but the more difficult to work. The more they incline backward the more easily they will work, but the more slowly they cut. M-shaped teeth (Fig. 262) are now largely used for crosscutting, chiefly in America, and as they have cutting edges both back and front they will cut in both directions. Usually, they are bevelled and set alternately, and they cut rapidly if kept in good order, The teeth of Disston’s American saws (Fig. 263) have less set than those in most English saws. Figs. 264 and 265 represent pit saw teeth. The form of tooth shown by Fig. 264 may answer fairly well for soft wood of ordinary thickness, but for thick timber, and especially the harder kinds, such teeth will cause jarring and bad work. Teeth as in Fig. 265 are the more suitable form. Of course, with all saws, the harder the timber to be sawn the more obtuse the angles of the saw teeth. The teeth in a saw cutting hard wood should be about 5/8 in. apart, and for soft wood, 3/4 in. For cross-cutting logs with a two-handled saw, a saw with teeth similar to Fig. 266, instead of ordinary cross-cut teeth, can be recommended, as it is much quicker and cleaner in cutting. These saws were invented and are largely used in America. The cutting is done by the single teeth, the double ones acting as clearers, and being filed about 1/32 in. shorter than the scoring teeth. The teeth are often formed on both edges of the blade, and when one set are worn down, they are knocked off, and the other edge of the blade used. The saw is made slightly curved; the handles are reversible. Fourteen gauge steel is used. This form of saw is rapid and easy to work, and does not bind in the cut; at the same time comparatively little set is required. It will cut well both hard and soft wood.
Fig. 254.—Cross-cut Saw Teeth.
Fig. 255.—Cross-cut Saw Teeth for Hard Wood.
Fig. 256.—American Cross-cut Saw Teeth.
Fig. 257.—American Cross-cut Saw Teeth.
Fig. 258.—Saw Teeth filed hollow: Incorrect.
Fig. 259.—American Regulating Saw Teech.
Fig. 260.—American Lightened Teeeth.
Fig. 261.—American Peg Teeth.
Fig. 262.—M-shaped Saw Teeth.
Fig. 263.—Disston Saw Teeth.
Fig. 264.—Teeth of Pit Saw.
Fig. 265.—Teeth of Pit Saw.
Fig. 266.—Teeth of Two-handled Cross-cut Saw.
SAW VICES.
For holding a saw during the process of sharpening a saw vice will be required. This is made in various forms, one of which is shown by Figs. 267 and 268. It can be made of any hard wood, such as oak or mahogany. It consists of two parts, hinged together at the bottom a; an iron screw working in a plate or nut is placed in the centre b for the purpose of tightening up the jaws d between which the saw is placed. The piece cut out at c is to allow the back of a, tenon saw to pass through.