How to Sharpen ToolsUpdated: Feb. 21, 2023
A bench grinder, file and cone-shaped blade balancer are the key tools for creating a sharp edge and well-balanced blade.
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- An hour or less
Sharpening your tools
Years ago, I drove by a storefront with a hand-painted plywood sign. It read “Tool Sharpening.” Curious, I gathered a boxful of dull old handsaws and circular saw blades in my garage and carried them up to the store with the hope of getting them sharpened.
Inside I saw a lean old fellow with wisps of gray hair curling from the backside of an old hunting cap. He was hunched over his vise illuminated by a single 150-watt bulb hanging from the 12-ft. ceiling. There were tools everywhere in the shop and boxes with layers of dust several years in the making. I interrupted him in mid-stroke of filing an ax by saying I had some blades to drop off to get sharpened. He told me to leave them by the door, write my name on the box, and come back in a week. I felt uneasy about his apparent lack of concern for my stuff, but I thought I’d chance it and see what happened.
A week later when I walked into the store, he asked me what my name was and started rummaging through a pile of bags and boxes. Magically, he found my box in the midst of the clutter and handed it to me along with a modest bill. I paid him and took the tools home. The handsaw cut through a 2×4 as if it was butter, and the circular saws were equally impressive!
The next day I gathered my garden tools and brought them down to the same shop. As I entered the store, he said, “I can’t do those for you.” I asked him why and he explained that the building was just sold to a coffee shop and he’d be closing his doors for good. “I’m retiring, going fishing,” he said. I asked him where I could take the tools, but he had no suggestions.
A moment passed, then he looked me in the eye and said, “Why don’t you do it yourself?” I shrugged my shoulders as he motioned me to come around the counter with my box of garden tools. He proceeded to pull each tool from the box and explain how to sharpen them. For the next two hours, he stood over my shoulder as I ground and filed each tool.
That afternoon changed forever how I look at tools. As small shops like his disappear from the urban landscape, I’m thankful for the confidence this guy instilled in me, and I try to emulate the skill he used in handling the edges of tools. Don’t get me wrong—I still send out my handsaws and circular saws to a big sharpening business in the next town—but lawn tools take less time to sharpen than the drive there. You can also apply the same techniques to hoes, hatchets and mauls.
Do It All with Three Simple Tools
A Grinding Wheel, a Mill File and a Sharpening Stone
You can sharpen most garden tools with a simple 10-in. mill bastard file (Photo 5). A synthetic finishing stone will further smooth the blade edge, which is important, especially on an ax or hatchet. You can get one at any hardware store. You don’t need a fancy Arkansas stone for garden tools.
A grinding wheel (shown in Photo 4) is good only for removing larger amounts of steel. Grinding is a better choice than filing if you have to get rid of nicks in the blade, or you’re trying to restore an especially worn blade. One strike against the grinder is that it may get the blade so hot that the temper (built-in hardness) of the steel could be ruined. If the steel turns a straw color, it’s done for. If you must use a grinder, keep a bucket of water handy to douse and cool the blade after every pass across the wheel. With practice, you’ll know how much grinding an edge can take before it gets too hot. For most of the grinding shown here, a coarse wheel will work fine.
You can buy all these sharpening tools at home centers and hardware stores.
Lawn mower blades: Sharpen and balance
Photo 1: Block the blade
Remove the spark plug wire. Then clamp a 2×4 block to the shroud to keep the blade from turning as you remove it.
Photo 2: Remove the blade
Squirt penetrating oil on the bolt head that holds the blade to the engine shaft. Give the oil 15 minutes to work its way into the threads. Using a socket wrench, turn the nut in the same direction you would to remove a lid from a mayonnaise jar. Mark the blade on the bottom so you can install it properly again.
Photo 3: Inspect the blade for cracks
Examine your blade carefully. If it’s cracked like this one or missing a chunk, toss it or put it in the recycling bin and buy a new one.
Photo 4: Sharpen the blade with a grinder
Grind the tapered cutting edges with a grinder only if you see nicks in the blade. Follow the factory angle of the cutting edge. The grinder will remove nicks in the blade much faster than you can file them. (If you don’t have nicks, go to Photo 5.) Don’t overheat the blade! Apply minimum pressure and move the blade across the coarse grinding wheel. Dunk the blade end in a bucket of water after each pass to keep it cool, then wipe it with a rag. Keep the rag clear of the grinder. Tip: Keep the piece moving as you grind so you don’t overheat the steel. Burning the steel will weaken the edge, making it become dull sooner.
Photo 5: File the edges
File the ground edge with a 10-in. mill file. Keep the angle consistent and use long, broad strokes away from you. Use firm pressure and push the file and your arms from your shoulders, not your wrists.
Photo 6: Check the blade’s balance
Balance the blade with a special plastic balancer available at hardware stores. Mark the heavy end and grind steel from the very end of the blade (not the cutting edge) to reduce the weight.
The last time I tipped my mower on its side to remove the blade, I couldn’t get it started again. A piece of dirt got lodged in the carburetor needle valve, and I had to remove the whole carburetor and clean it to get it going.
Another reason not to tip it on its side is you won’t have to deal with spilled gasoline. The best way to do it? Set your lawnmower on top of sawhorses to get at the blade.
Although it’s unlikely, the engine could start if you rotate the blade, so pull the spark plug wire before touching the blade. Once you remove the blade (Photos 1 and 2), you’ll notice an edge about 3 in. long on each end of the blade. These are the edges you’ll be sharpening.
Learn how to sharpen a lawn mower blade in our video tutorial.
Never wear gloves, neckties or shirts with loose sleeves around a spinning grinder. Also, keep long hair tied up or tucked under a hat. Although the heat of the sparks isn’t intense, keep your hands clear of the direct spray of sparks from the grinder.
Axes: File and hone
Photo 8: How to sharpen a hatchet, ax heads have beveled edges
To learn how to sharpen a hatchet, clamp the ax head in a vise and file the original bevel as shown. Use long, broad strokes from your shoulders outward. Examine the edge and follow the original bevel. Next, flip the ax around in the vise and file the other side. You must maintain the edge in the exact center of the ax.
Photo 9: Use a sharpening stone on the ax
Grind the filed edge with a sharpening stone. Squirt a generous amount of honing oil on the stone and use a swirling circular motion into the blade. Keep the bevel the same as before. Use the coarse side of the stone first, then the fine. Keep lubricating the stone with oil (use water for a special water stone) for a clean edge.
Not all axes have the same blade bevel, so it’s important to follow the original bevel. Inspect the ax blade for any chips or nicks. If you find some nicks, grind them away with the grinder. Do the whole edge to preserve the shape of the blade. When learning how to sharpen a hatchet, you must be careful not to burn the edge. Keep a bucket of water handy to douse the head after each pass, then dry it off and continue grinding.
If your blade has only small nicks or irregularities, you can usually file them away with a 10-in. mill bastard file. Filing produces very little heat, so you won’t need to worry about ruining the temper of the blade. Follow Photos 8 and 9 to get a blade as sharp as a pocketknife. If you have any visions of shaving with your ax like the lumberjacks of folklore, forget it. It’ll be sharp, but not that sharp.
Shovels: 20 strokes with a file
Photo 10: File the edge with a mill file
File along the blade of the shovel from each side to the center. Move the file in one continuous motion for a consistent edge. The angle should be about 45 degrees. It’ll take up to 20 strokes per side for a good edge. Use a bar clamp to hold the shovel firmly to the bench.
Sharpening a shovel is one of those things most people don’t think of doing, like cleaning the coils of a refrigerator. Once your shovel is sharp, the task of digging almost becomes fun. Along with sliding easily through soil, it’ll cut right through stubborn roots and sod.
In most cases, you’ll only need a file to sharpen a shovel, but if the edge has some chips or deep nicks, use the grinder first to reshape the edge, then file as shown in Photo 10. Once the shovel is sharp, don’t worry about the burrs you’ve created on the backside; they’ll disappear the minute you start digging.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
- Hearing protection
- Safety glasses
Required Materials for this Project
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.
- Honing oil