by J.M.Drew St. Paul Publishing Company 1918
- HOME -Farm Blacksmithing
The saw is one of the woodworker's most useful tools and is used for cutting wood either across or with the grain or fiber. The one used for cutting across the grain is called the cross-cut saw; the one for cutting with the grain, the rip saw. It is poor economy to buy a cheap saw; and on the other hand, it is sometimes unwise to buy the highest priced; as some saws are made very hard and are intended to be used only by fine mechanics in dry lumber, and will not stand setting nor rough use. A good saw for ordinary use is Disston's D 8 with sway back. There are other saws which are probably as good, but the one mentioned is a standard saw and will give good service. The sway back makes it lighter at the point and easier to handle than the straight back. The size of saws is given by the length of the blade in inches. Twenty-six inches is a good length for a cross-cut saw, and twenty-eight inches for a rip saw. Saws for small work should be shorter.
The coarseness or fineness of a saw is shown by the number of teeth to the inch. A cross-cut saw for ordinary work should have about eight teeth; for rough work or for sawing large timbers seven or six would be better, and for fine work nine or ten. A rip saw for ordinary work should have about five and one-half teeth to the inch; for rough work, more, for fine work less. The number of teeth per inch is usually stamped on the blade of the saw near the handle.
The filing or sharpening of a saw consists of four operations which should be done in the following order: First, top-jointing,-which consists in filing off the points of the teeth until they are all the same length and making the cutting edge of the saw, taken as a whole, either straight or crowning-never hollow. Fig. 1 shows a home-made saw jointer which is used for holding the file exactly square across the saw care must be taken to have it square or the teeth will be shorter on one side and the saw will run crooked. A saw should be top jointed every time it is filed.
Second. Setting; which consists in setting or bending the teeth outward, one on one side, the next on the other and so on till all are set or bent. The object of setting is to make the saw cut wider than the thickness of the blade in order to allow it to run freely through the timber and not pinch. The amount of set in a saw may be readily seen by holding it to the light with the back toward the eye, when it will appear as in Fig. 2. Care must be taken not to give the saw too much set or it will run hard and not cut smoothly. For ordinary work the teeth should be set out about one-third the thickness of the blade. For dry lumber the saw will require less set, and for green or wet lumber, more.
The teeth should not be set too near the points nor too close to the blade; about two-thirds of the distance from the points to the bottom of the teeth is about right. This we will call the depth of set. Fig. 3 shows one type of saw set in which the amount of set is regulated by the screw A. Turning the screw in gives the saw less set; turning it out gives it more. The depth of set is regulated by the screw B. Turning it in will set the teeth nearer the point; turning it out will set it nearer the blade. The plate or anvil, C has four faces which may be turned to suit the size of the teeth.
Third. Filing; which consists in tiling the teeth to sharp points. Great care mast be taken in filing to bring the teeth to sharp points. If they are not sharp they will not cut and will prevent those that are sharp from cutting. Be careful also not to file them after they are sharp as that will shorten them and then they will not cut. The secret consists in stopping just when each tooth is filed to a point. To get the best results from a saw, the teeth should all be sharp and exactly of the same length and shape. Fourth. Side Jointing; which consists in running a fine file or an oil-stone along the sides of the saw to even the teeth at the sides to prevent scratching. In setting a saw it is impossible to bend all the teeth exactly the same; some will be bent or set out more than others, and if not side-jointed they will scratch, making the cut rough and uneven, and the saw will not cut 80 fast as it would were the teeth in perfect line. When a saw has too much set some of it may be removed by Bide jointing.