To sharpen a saw, you need a way to hold it securely while you’re filing it. “Official” saw vises are available at second-hand sources (or this great new one from Gramercy) but it’s very easy to make a superior one from a scrap or two of plywood. And, you can make a saw vise that’s closer to the length of your saw than commercial ones, which will save you time re-positioning the saw as you’re working on it. Be sure to have good lighting available. One or two easily adjusted, swing-arm lamps are perfect for the task.
Saw sets are readily available and affordable, both new and used. The basic “pistol-grip” style works well. As you squeeze the handle, a small steel plunger pushes against an adjustable, beveled anvil. Some saw sets have a rotating disc with a ramp that’s beveled such that as you turn the adjuster, a different part of the ramp is presented to act as the anvil, modifying the amount of set that the tool will perform with each squeeze. Others have a sliding beveled anvil that is adjusted up and down to dial in the amount of set. The teeth are set in the same direction that they were set previously. Setting a tooth the wrong way — bending it all the way to the other side — can weaken it or even break it off. Take care to match the set direction. The saw set is positioned over the saw blade, a suitable tooth is located, the handle squeezed and the plunger pushes the tooth against the anvil,
bending it the right amount (more later).
The simple guide on the end of the file offers a visual reference to keep the file cutting the proper rake angle on each tooth. The fleam guide, the parallelogram with a slot pictured here on the bench gives a similar reference when filing cross-cut teeth that need an angled bevel. You simply hold your file parallel to the fleam guide as it sits over the saw blade.
You’ll need an 8″ or 10″ smooth-cut flat file for jointing and a small triangular file for tooth shaping and filing. There is plenty of advice available about triangular file sizes, but Mike Wenzloff of Wenzloff and Sons says to use the smallest file that will fully
file the back of the next tooth. A smaller file has a sharper corner and will cut the gullet — the concavity between teeth — deeper for better chip clearance. He also tells me that he can sharpen over twenty saws with a file before the file wears out.
Always use a file handle. The control required, and the comfort you deserve, make this mandatory. Also, those small triangular files have tangs that will hurt you if left unhandled. You can make a handle easily enough but they’re inexpensive to buy and reusable. Filing is usually a two handed job so some sort of “handle” on the other end of the file is a good idea. This outboard handle can be a simple scrap of wood with a hole drilled all the way through to receive the file. The hole should be small enough that the file can be lightly driven in. This additional handle will act as a guide to keep the file rotated to file the proper rake angle in the teeth. To make it easier to reuse this rake angle guide, you may want to mark the rake angle on both sides and to identify which side the handle of
the saw is on so you can line everything up next time you use it.
Speaking of guides, a fleam or bevel-angle guide is handy for filing cross-cut saws. You can lay a bevel gauge set for the correct angle on the bench behind the saw vise or cut a slot in a scrap of wood (both sides) that you slip over the teeth near where you are filing. Either will serve as a visual aid and help keep your file at the proper angle.
Setting (before jointing)
Setting saw teeth before jointing assures that the tops of the teeth will all cut in the same plane. If you set after filing, your flat-topped, jointed teeth will be bent slightly outwards. And, those flat-tops will be bent out of plane with each other. Because professional saw sharpeners debate whether to set before or after sharpening, it seems to me to be a matter of personal preference. As your experience with saw sharpening grows, the difference(s) should become more obvious and you’ll probably end up in one camp or the other. To set the teeth, you can clamp the blade in the saw vise such that the teeth are enough above the jaws to allow comfortable access with the saw set. As sawmaker Kevin Drake says: “I find it more comfortable to just hold the saw in my left hand and set the teeth with my right. My hands sort of wiggle down the saw as this happens.” Sawmaker Mike Wenzloff adds: “holding a saw in one’s lap works with smaller back saws. Not so well on 28″ 4 tpi rips.”
Begin setting with the teeth closest to the handle. Because those teeth get far less use you can use them to fine tune your settings. Adjust your saw set according to the manufacturer’s instructions. often the anvil adjustment is based on a scale of teeth per inch, but when it comes to any one saw, this may not be accurate. And some saw-set scales are just arbitrary reference numbers. Start with a setting that corresponds to more teeth per inch than your saw actually has. That should make for a smaller amount of set; a good
place to start as the saw set’s settings aren’t the code, they’re more what you’d call guidelines than actual rules. Select a tooth that’s set away from you and position the saw set over it with the plunger pointing at the tip of the tooth. Squeeze the handle to set the tooth. Move the saw set over, skip a tooth, and set the next one that’s going away from you. Do a couple more, applying pressure evenly with each tooth, turn the saw around and set the teeth you jumped over in that same section so that you have an inch or so of set teeth. Now measure. Compare the width of the blade stock to the overall width of the teeth you just set. The set of the teeth should increase the thickness of the blade by about 20% for dry hardwoods; up to 30% for soft- and green woods.Example: A saw blade with a thickness of 0.035″ (0.9mm) should be set to a width of 0.042″ (1.1mm) for hardwoods and 0.045″ (1.2mm) for softwoods. Notice how little set there really is: the total thickness is increased by only .007″ (.18mm) to .010″ (.25mm) so any one tooth is set just .0035″ (0.09mm) to .005″ (.13mm) — that’s only three and a half to five thousandths of an inch. That’s not very much, and because it is easier to add more set than it is to remove, use care not to over do it. After measuring and subtracting, adjust your setting procedure to accommodate the new data and continue to set the saw.
This concludes part 2 of this excerpt from The Perfect Edge: the Ultimate Guide to Sharpening for Woodworkers by Ron Hock. Stay tuned for the thrilling conclusion.