Sharpening Saws

You might skip over this part until you calm down, unless you find, like me, that the concentration required for saw sharpening can help you regain your peace of mind. There are four steps in sharpening a handsaw: jointing, shaping, setting, and sharpening.

Jointing is the process of making sure that all the teeth are at the same height. Clamp the saw, teeth up, between boards in a vise or in a special saw-sharpening clamp. Take a fine flat file and lightly drag it square along the length of the teeth precisely perpendicular to the side of the blade. Joint lightly until you brighten the tips of all the teeth. One or two passes should be enough.

Shaping, the next step, puts the teeth at their appropriate profile for their allotted task. Both crosscut and rip teeth are shaped with the same equilater-ally triangular file called a "slim taper." The 60-degree angles of the corners of this file can cut both shapes of teeth, the difference being made by the axial tilt given to the file as you work.

Finer saw teeth call for finer files. Saws with four to eight points to the inch need a six-inch slim taper file. Those with nine or ten points need an extra slim, and a double extra slim file will be required for saws with 11 or 12 points. Even more finely toothed saws will need a five-inch superfine file.

Rip teeth are filed so that their cutting face is at 90 degrees to the line of the tops of the teeth. Thus, if the handle of the saw is to your left as you are filing, you shape the teeth with the left face of the triangular file held vertically. Crosscutting teeth, however, are shaped with a 12- to 15-degree slope off the vertical on their faces, and the file must be held accordingly.

Shape the teeth on a ripsaw by filing straight across without dipping the file on either side. On crosscuts, you can hold the file at the sharpening angle, but concentrate on the shape of the teeth, not their acuity. Start at one end on the face of a tooth that leans away from you and file it and the back of the adjacent tooth until you reach the middle of the flats caused by jointing. Skip to the next gullet where the face of the tooth leans away from you and do the same thing. Work your way down the length of the saw, doing every other gullet and then reverse the saw in the vise and repeat the process down the other side. On this second run, the filing should take off the remaining half of the jointing flat, and the teeth will all be sharply pointed and equal in depth, height, and angle.

Once the teeth are all the proper size and shape, they can be accurately set. Setting the teeth means bending them slightly to alternate sides, right and left in turn. The set gives the blade clearance in the kerf and makes a huge difference in how the saw performs. The maximum amount of set to put into any given tooth is to have it lean one-third the thickness of the blade to the side, bent at a point halfway down from the tip. You may want this maximum amount for coarse cutting in green wood and considerably less (or none) for dry. You can always add more set if you don't have enough.

There are numerous devices for setting saws, some easier to use than others. Patent pistol-lever saw sets are the easiest to use, as well as the easiest to overset the saw with. If you don't have the instructions that came with such a set, experiment on your saw at the handle end, starting with what appears to be the minimum adjustment. Set the teeth from both sides or you won't be able to tell what the total effect will be. The set must be equal on both sides of the saw or it will tend to pull to the side.

The saw wrest is a wrenchlike slotted bar used to bend individual teeth or to twist adjacent pairs of teeth in alternate directions. By setting the slot on the tops of two teeth and turning the handle to the side, you bend one in one direction, the other in the other direction. You work your way down the length of the saw, two teeth at a time. The same saw wrest will also let you bend just individual teeth right and left. M

Shaping corrects the profiles of the teeth.
Setting bends the teeth to alternate sides, keeping the saw from binding.
Sharpening gives each crosscut tooth a knifelike edge.
Sharpen ripsaw teeth square across.
A tap of your hammer "cocks" the holdfast in the slightly oversized hole.

Sharpening puts the edge on the teeth. For crosscutting teeth, work on the face of a tooth that leans away from you, except now angle the handle of the file back at 45 degrees toward the handle of the saw. Don't dip too much, just angle back. File the face of one tooth and the back of the adjacent tooth simultaneously until you form half of the point on each of them. Do every other pair down one side of the saw, and then flip the saw around to do the remaining teeth.

After setting, rip teeth may no longer be properly oriented. Bending the teeth to the sides cants the angles of the tops, and twisting the teeth cants the angles of the faces. You may need one more light jointing pass and then a light shaping pass from opposite sides of the saw.

As a final touch on crosscuts, lightly pass a whetstone held flat down both sides of the blade to ease the burrs from filing. I have always sharpened by filing the faces of teeth that lean away from me, going with the set of the teeth. Filing against the set leaves less of a burr, but the final stoning always takes care of that anyway.

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