How Do I Sharpen Mower Blades?

There are several reasons why your lawn should be cut regularly: it stimulates grass growth, increases grass density and keeps your space looking fresh and taken care of. However, if your mower blade is not sharp, this could leave you with a less-than-beautiful lawn. While a sharp lawn mower blade cleanly cuts individual grass blades, a dull blade can rip the grass instead of cutting it, which can severely weaken blades and make the lawn more prone to disease and distress (e.g., weed development). 


To help maintain a sharp blade and prevent lawn damage, you should replace your blade at least once a season and sharpen it throughout the season to maintain optimal performance. Though it’s always best to replace dull blades, you can also sharpen blades throughout the season to maintain optimal performance. This will help maintain your lawn's health and appearance. Here are the steps you should follow to renew your mower's cutting abilities:



Before you sharpen

1. Always disconnect the spark plug to prevent injury. To avoid leakage into internal parts of the engine, remove the gas from the tank. Tip the mower on its side so the air filter is facing up.

2. Wearing gloves for protection, secure the blade with the Universal Blade Removal Tool or a block of wood. Remove the bolt and retaining hardware. These parts hold the blade and blade adapter to the engine crankshaft, which need to be removed from the mower to sharpen the blade ' do not attempt to sharpen the blade while it is still attached to the mower. 

3. Identify and mark the downward-facing side of the blade. Many times, homeowners will take the blade off, sharpen it and reinstall it upside down, which means the blade won't cut the grass ' no matter how sharp it is. Mark the bottom side of the blade with a small dot of spray paint so you know how to reinstall it correctly once the blade is sharpened. Our blades either have the word 'bottom' on it or the part number to designate that it is the bottom of the blade.


Sharpening the Blade

Whenever you sharpen the blade, remember to always wear eye protection, gloves and long sleeves to stay safe and avoid anything harming your skin. If you don't have the tools to handle the job yourself, contact your nearest lawn repair service for the needed work. 

Typically, blades can be sharpened with a metal file or on a grinding wheel. If you're using a file, clamp the blade in a vise and sharpen the cutting edge with a hand file. Always sharpen from the top side of the cutting edge to give you the longest-lasting edge on your blade. Keep the file at an angle of the bevel of the blade as you sharpen and press hard enough to feel the file cut into the steel on the blade. When it comes to sharpness, you don't want the blade too sharp, as it will dull quickly ' think of a butter knife in terms of sharpness for your lawn mower blade. 

The blade can also be sharpened with a machine like a bench grinder or a belt sander. When using a bench grinder, move the blade back and forth against the wheel of the grinder while maintaining the original angle of the blade's bevel. If you're using a belt sander, rub the blade at an angle against the sandpaper to gradually sharpen it through friction. When a blade becomes worn or damaged beyond repair, it's time to replace it. Depending on your needs, you'll want a standard, high-lift, or mulching blade.