The teeth are set by bending every other tooth outward, first setting those on one side and then those on the other. You should do this with some one of the various adjustable tooth-setting contrivances sold for the purpose, as it requires a skilled workman to set teeth in any other way, and any attempt on your part to do so without some instrument adjusted to the purpose will probably result in damaging the saw.
For soft and loose-fibred wood more set is needed than for hard wood, because the fibres, which are quite cleanly cut or broken in the hard wood, in the more yielding soft wood are bent aside by the teeth to close in upon the blade with considerable binding force; and less set is required by fine work than for coarse. The angles and points of saw teeth can be more acute for soft than for hard wood.
To sharpen the scraper you must have a sharpener or burnisher. The edge of a chisel or any piece of very hard steel can be used after a fashion, but it is better to have a regular tool for the purpose, which can be made easily from an old three-cornered file, such as is used for filing saws, by grinding off the teeth and slightly rounding the angles on the grindstone until the whole tool is smooth. Two opposite edges of the scraper are ground or filed and the edge then turned over by the burnisher. Some workmen grind the edges with an obtuse bevel and use only one angle of each edge. Others grind the edges square and use both angles of each edge. The bevel gives a slightly keener scraping edge than to grind the steel square, but it requires more frequent sharpening and the squared edge turned over on both sides is likely to be more satisfactory.
Fig. 673.
Fig. 674.
First grind or file the two opposite edges squarely across and slightly round each corner to prevent scratching the wood. If there is a burr at the edge it can be removed by rubbing the scraper lightly on the oil-stone, but this is advisable only for final scraping of very fine work. Having thus got the edge at right angles and smooth, lay the scraper flat on its side near the edge of the bench and rub the burnisher back and forth a few times in the position shown in Fig. 673, which is almost flat on the scraper. This rubbing bends a little of the steel over the edge. Do this on each opposite edge of the two sides, giving four edges thus curled over. Next, holding the scraper as shown in Fig. 674, draw the burnisher with a firm, even stroke, once or twice, lengthways of the edge, as shown. The scraper can be laid flat on the bench, if preferred, slightly projecting over the edge. Notice that the tool should be drawn with a slightly end to end motion, as shown, which helps turn the edge. This turns a fine scraping edge, which will take off shavings. All four edges are treated in the same way. After one edge gets dull, use another. When all four are dull, resharpen with the burnisher as before, without grinding or filing the edge. This can be done a few times, but soon the edges will get worn off and rounded, and the scraper then needs refiling.
Shellac.—See Finishing.