3 Easy (and Safe!) Ways to Sharpen Your Lawn Mower Blade
A well-maintained lawn mower will keep your lawn looking fresh, and it starts with sharpened blades. We show you how to do this easily and safely.
Save yourself time and money while making lawn care a priority this summer, and get in the habit of sharpening your lawn mower blade yourself. A sharp blade cuts faster and causes less damage to the grass in your yard. It’ll create clean cuts, whereas a dull blade can fray the ends of the grass and pull at the roots of your lawn. Manufacturers recommend sharpening the blade after every 10 hours of use, but you may need to do it more often if you’re running over debris like branches and pinecones.
Remove the Blade From the Mower
Use a wrench or your hand to loosen the bolt that holds your lawn mower’s blade in position. My lawn mower folds to store compact and upright, which makes access to the blade easy. If you’re tipping your lawn mower to reach the bolt, it’s a good idea to check your user manual to make sure you don’t accidentally saturate the air filter with oil or flood fuel into the engine. Either can happen if you tip the lawn mower the wrong way — always keep the spark plug tilted towards the sky.
Note: Put the lawn mower up on blocks, so you can access the underside without having to tip it.
3 Methods to Sharpen the Blade
When you’re sharpening your lawn mower blade, the goal is to make the blade as sharp as a butter knife. It doesn’t need to be razor-blade sharp to be effective since it rotates at a high speed.
Method 1: Clamp and File
A flat file is an easy tool that'll sharpen a dull blade (with the blade secured in a vice.) Apply pressure to the file, and run it perpendicular to the edge of the blade to grind down imperfections in the metal and hone the shape of the existing edge. Once you’ve done one side, reposition the blade in the vice to do the other side. The process is slower than using a hand file, but it works!
Method 2: Use a Bench Grinder
The fastest way to sharpen a lawnmower blade is with a bench grinder. Wearing protective eyewear, earplugs, and work gloves, grind the edge of the blade against the spinning wheel. It'll be loud and you'll see sparks, but you’ll be able to sharpen the blade in a matter of a few minutes. A bench grinder is also great for repairing a heavily-damaged blade that’s riddled with gouges that are hard to file smooth by hand.
Method 3: Use a Drill and Blade Sharpening Stone
A blade sharpening drill bit operates much like a bench grinder, but on a smaller (and more affordable) scale. It’s faster than hand filing, and the stone of the bit is designed to hug the edge of your lawn mower blade, making it easy to sharpen with little effort and room for error.
Reinstall the Blade
The only critical part to remember when you’re installing your lawn mower blade is to get it tight. After you’ve reassembled and threaded the bolt by hand, use a wrench to tighten it down. Start it up over the lawn, and enjoy how easy lawn care can be when you have a freshly-sharpened blade.