Saw Blade Sharpening

A good handsaw, when properly treated, is a tool that can be passed with pride from one generation to the next. Essential to proper treatment is storing the saw correctly, in a place where the blade is protected and the atmosphere isn't too damp. An occasional wipe with a rag dampened with machine oil is good for the blade, too.

Over time, however, the best of handsaws, even those that are treated with proper care, get dull. The millions of collisions that the teeth experience in cutting wood both dull them and reduce their amount of splay (called "set"). The saw will begin to cut more slowly (because the teeth are dull) and tend to bind (because the set has narrowed).

Fortunately, it doesn't take a magician to sharpen a handsaw. A little time, the proper tools, and a couple of simple techniques will restore that blade's cutting edge.

The Tools. You'll require a saw set for resetting the teeth, and a taper file or two. Both saw sets and taper files come in different sizes, so you'll need to determine the number of teeth per inch in the saw (or saws) you will be sharpening, and use a set and file that are appropriate to it.

Inspect the Saw. Remove any rust from the sawblade using fine sandpaper or a wire brush. Look closely at the teeth: Are they all the same height? If not, you will need to perform an operation called jointing. Simply clamp the saw in a vise, using wood blocks as a backboard to hold the spine of the saw rigid. Then file the teeth until they are of uniform height. Use a double-cut, smooth metal file for the job, clamping it to a piece of scrap in order to keep it square to the saw blade.

Setting the Teeth. This step is necessary to make sure that the kerf is the proper width: Teeth that are out of alignment, regardless of their sharpness, will cut unevenly. The saw set makes this job a bit less painstaking, and ensures a more uniform set to the teeth.

The saw set resembles a pair of pliers, with a pair of long handles at one end, a small pair of jaws at the other, and a pivot in between. At the jaw end there is a rotating disk that, when turned, adjusts the travel of the tool, meaning that the plunger and anvil mounted on the jaws are closer together (or farther apart) when the handles of the tool are squeezed. When the set is then positioned against a tooth to be set, the tool will bend the tooth to the precise angle required for that size of saw.