How To Sharpen Your Lawn Mower Blades (The Safe Way)

Sharpening your lawn mower's blades should not only form part of your regular maintenance schedule, but it's also essential to ensuring a nice, clean cut on your lawn. If you notice the finish after a fresh cut is uneven, or if it's taking longer than usual, then these are common signs that it might be time to sharpen your blades. Other signs include dull, brownish-grayish grass and a torn or frayed finish to the grass tips. It's also worth noting that sharpening blades isn't always the answer, as you will also need to replace your lawn mower blades from time to time.

Once you've established that it's time to sharpen your lawn mower's blades, the next thing on your mind should be safety. After all, regardless of whether you own an electric or gas-powered mower, these are powerful machines and mis-handling them could end up in serious injury. While it is possible to sharpen the blades in situ, it's much safer to remove them, as this removes all risk of the mower firing up and spinning that blade while you're working on it. Removing them will let you sharpen them with no risk of injury. We also recommend using a bench vise in order to securely clamp the blade as you file it.

To complete the job properly, you'll want a few tools handy. Before starting, ensure you have a bench vise (or similar), a hand file, some cleaning rags, and a wire brush, in addition to a spark plug wrench and steel pipe or wooden block to help with removing the blade. Don't forget your safety equipment too — thick gloves and safety goggles are advised.

To begin, disconnect the mower's spark plug — or simply make sure it's unplugged if you own an electric one. Next, in order to gain access, tip your mower up so that the air filter is up. Doing this stops fluids like gas or oil from entering the filter, which will then burn off emitting clouds of smoke when you next go to mow. To remove the blade, wedge your pipe or wooden block against the blade to ensure it cannot spin while you wrench it. Now, simply wrench it off.

To sharpen the blade, clamp it in your bench vise and begin filing it. Remember, you're looking to achieve something akin to butter-knife sharp here — there's no need to work at it until it's sharper than a butcher's knife. Before fixing your blade back to the mower, now's the perfect time to balance the mower's blades — an essential step to ensure an even cut once installed. When refitting the blade, take care to install it the correct way up, and make sure to tighten it to the correct torque as specified in the manual.