Sharpening a bow saw routinely prevents the blade from becoming dull. It is important to know whether your bow saw has special hardened teeth, which is very common in the saws sold today. This can be determined by consulting a representative at a local hardware store. Bow saws with special hardened teeth cannot be sharpened, and attempting the sharpening process on them will damage them and make them potentially unusable. The sharpening process is not overly difficult and only requires a few tools available at a hardware or home improvement store.
Place the bow saw in the saw vice and file it with the flat file until all the saw teeth have a flat top.
Run the three-sided file over the saw teeth so that each tooth receives at least three total strokes of the file. When this is complete all teeth should look identical.
Position the saw set handset at the end of the bow saw blade so that the stamps on the set point to the first tooth. Press the grip on the handset together to set the tooth. Repeat this for all of the saw teeth.
Clamp the bow saw in the saw vice very close to the base of the teeth. File the teeth with the saw file at a horizontal, 60-degree angle.