Tool Sharpening Basics

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First make sure it's balanced end to end. Set the center of the clean (no grass on it) blade on the corner of your file and see if both sides weigh the same (Fig. 8). (The center should be at the middle of the main hole. You can measure in from both ends to make sure.) If one side sinks, file a little bit off the back edge of that heavy side, and balance it again. Don't neglect this step: Dennis Burkholder (who once helped design mowers) says it's just as important as sharpening the blade. Otherwise, your blade may wobble when it spins, and that 3,600 rpm shimmy will eventually wear out the oil seals on the blade's shaft. You'll find yourself with a strange-and expensive-problem to fix: "Whenever the motor of my mower warms up, oil runs out the bottom.

" Once the blade is nicely sharp and balanced, put it back on the mower-cutting edge up. (That position, coupled with the airplane like lift created by the up-curve in back of the blade, helps keep cut grass up off the ground so it can be blown out. By the way, if you put the blade on upside down, you'll be surprised by how poorly it cuts-I sure was!)

Pruning shears? Grass clippers? Tin snips? You can file them into shape, no problem. Remember, they're single-beveled tools.

So if you mess with the insides of those closing blades (except to lightly remove burrs), don't blame me for what happens. Actually, if your pruning shears aren't cutting well, it may be that there's too much play between the blades. Tighten the nut in the middle and see if that helps. Heck, you can even sharpen one of those jagged-edge hand

swing blades (also called grass whips) with a file. Run it down the bottom cutting side and it'll get both the peaks and valleys of the blade (Fig. 9). OK, it's time to move on to a more labor-demanding subject: the

ax . To sharpen most dull axes, you're going to have to file back a shine on each side 3/8- to 1/2-inch long, and that means removing a lot of material. Woodwright Roy Underhill uses a single- or double cut file for this job, drawing the file back and forth along the side of the blade with both hands (Fig. 10). He says this technique makes it easier to keep an accurate angle while you work, keeps you from accidentally pushing your hand into the blade and leaves a smoother finish. Some other sharpeners I met feel that a dull ax requires so much filing that this is one time a power grinding wheel is a big help. If you do use a wheel, for Pete's sake, be careful. It takes off material awfully quickly, and as Collier Davis notes, "You can't put it back on.

" Then, too, if you let any part of your tool get too hot from rubbing against the wheel, its temper will be ruined forever. (Whenever the tool starts to get hot, dunk it in a bucket of water.) So go slow—the slower the wheel, the better. In fact, a hand-cranked sandstone wheel like Roy Underhill uses would be ideal. And follow these safety rules: Wear protective goggles with a power wheel. Hold the ax so it can't possibly jam or get snapped back at you. And keep your hands away from that wheel.

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