Filing a saw is truly a job for an expert. There have been others who thought they knew how, but ended up by ruining a saw instead. This is why it is not ideal that you tackle the job yourself. Nonetheless, it is a fine thing to know how to do it. You may discover one day when you really need that saw then you find out someone else has used it as a meat cleaver on a beef bone. Then you need to sharpen your saw. Start your saw-filing experiment on an old saw, not on your finely geared-up 22-inch crosscut. In saw filing, practice counts.
The saw must first be placed in a saw clamp and the points evened using a flat file or a handsaw jointer. Then set the teeth by bending every alternate tooth to the right or to the left to give enough clearance for the blade cutting. Set every other tooth on one side first, and next on the other side.
The best method is to employ the tool made for this work, a saw set. The shape of the body and handle of this tool lets the user to operate it with ease. The saw is held securely against the gauge while the tooth is being set. The saw teeth are in plain view, and that enables the user to align the tool quickly to the tooth to be set. The average set for a saw would require that the anvil must be adjusted that the lower line of the bevel is positioned about one-third the height of the tooth from the point. It must never be lower than half the height of the tooth, since it might cause the blade to spring or crack and has a tendency to break out a tooth.
Another way of setting the teeth of a saw is using a hammer and a special anvil, giving each tooth a sharp blow. This method, however, demands much skill.
The set of a saw varies based on the work; soft, wet wood calls for more set than dry hardwoods.
The saw is then readied for sharpening by filing the teeth using a three-sided blunt or taper file. The workman takes his position at the left of the clamp and at the point of the saw.
For crosscut saws, the file is held at an angle of 45 degrees and is permitted to drop into the gullet between the first and second tooth. This position of the file checks the location for each succeeding stroke. Each alternate tooth is filed, working from the point to the handle, filing on the front edges of the teeth. The saw is then turned around and the workman changes his location to the right side of the clamp. The remaining teeth are then filed in the same manner. When all the teeth have been filed, the saw is laid flat on the bench. A file or an oilstone is softly slipped over the sides of the teeth to even out any slight differences in the set, and also to take out any wire edge.