How to Sharpen Your Lawn Mower Blade for a Cleaner Cut

When your lawn mower isn't making the cut anymore, usually it's because the blade has lost its sharp edge from use. Removing the blade and sharpening it yourself can seem intimidating if you've never done it before. But it's actually a simple process, and you'll only need two tools to do it.

Once you know how to sharpen your lawn mower blade, it'll take you a fraction of the time it takes to mow your lawn. So, just follow this step-by-step guide to give your grass a crisp, clean cut again. Or, if you don't want to worry about sharpening the blade, you can just remove it and bring it to a lawn mower repair service near you to take care of it.

Test Garden Tip: When grass blades have torn, ragged ends that turn brown after a mowing, chances are it's time to give the blade some attention. Most experts recommend sharpening power mower blades once or twice a season, depending on how often you use your mower.

What You Need

• Wrench
• Medium file

Step 1: Remove Blade from Mower

Disconnect the spark plug on a gas mower or unplug an electric mower (to ensure the machine won't accidentally start while you're working on it). Next, gently lay the mower on its side and use a wrench ($27, The Home Depot) to remove the nut that attaches the blade to the motor. Then, remove the blade from the mower. To make sure you replace it the right way in the machine, mark the bottom of the blade with spray paint so you know that it should face the ground when you're done.

Step 2: File Blade

Clean any dirt or grass clippings off the blade with a dry cloth. Stabilize the blade in a vise and use a medium file ($10, The Home Depot) to smooth out imperfections along the blade edge (at the ends of mulching blades). Follow the existing angle of the blade, holding your file or sharpening tool at about a 45-degree angle. Move the file in one direction, gliding out toward the edge, much like you would sharpen a kitchen knife. However, your goal is to make the edge about as sharp as a butter knife rather than your favorite chef knife.

Step 3: Check for Balance

After you hone the cutting edge on both halves of the blade, check to see if the blade is balanced. An easy way to do this is to pound a long nail into a wall in your garage and rest the blade's center on the nail. If the blade isn't balanced, file a little more metal from the heavier side until it balances.

Step 4: Reassemble Mower

When the blade is correctly balanced, put the mower blade back onto the machine using a wrench. Be sure to tighten the nut securely back into place. And don't forget to reattach the spark plugs.