How to Sharpen a Lawn Mower Blade for a Cleaner, Healthier Cut

1. Remove the Blade. Disconnect the spark plug or unplug the mower. Tip the mower over and remove the nut securing the blade to the motor. Take off the blade.

2. File the Cutting Edge. Clamp the blade in a vise. Use a medium file to smooth imperfections along the cutting edge (at the ends of mulching blades). Don't attempt to hone a razor edge—just remove nicks and dullness.

3. Check Balance. After filing both halves, test balance. If unbalanced, remove more metal from the heavier side until it balances horizontally.

4. Reassemble. Reinstall the blade and tighten the nut securely.