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How to Sharpen Lawn Mower Blades – Tips and Tricks

how to sharpen lawn mower blades
Written by Brent Butterworth
Last Update: May 3, 2023

Save your money and time by taking out time to take care of your lawn this summer; you can start by sharpening lawn mower blades. Abraham Lincoln said, “If I had four hours to chop down a tree, I’d spend the first two hours sharpening my ax.”

Using sharp blades will only help to cut faster and lead to less damage on the edges of the grass since you can easily get clean cuts with less stress when the blade is sharp. On the other hand, dull blades will most time pull out the grasses from their roots.

Ideally, sharpening the lawn blade should be a practice carried out within 8- 10 hours of usage. In cases where the lawn runs over branches, pinecones, and other debris, then you will need to carry out the practice a bit often. Here are steps to adhere to if you intend to make this a reality.

How to Sharpen Lawn Mower Blades

How to Sharpen Lawn Mower Blades

Removing the Blade from the Mower

First, you need to remove the blade of course. Do the following:

  • Disconnect the power source

Separate the wire that connects the ignition from the spark plug. If you’re using a cordless mower for hills, then you need to take off the battery pack. Doing this will reduce the chance of the engine starting accidentally while you’re working on the machine. Draining off the gas in the tank is another important factor; this will help control fuel from spilling at the process of removing the blade.

  • Take the Blade out

Once you’re done removing the bolt or nut, go ahead to pull the blade out. But ensure you take note of which of the blade sides either face upward or downwards. Bolting the blade in a similar pattern is important to boost the efficiency of the machine.

  • Clean & Remove Rust from It

Tip the mower on one side. Tipping the mower will help you have access to the bolt or nut that retains the blade. Use a short woodblock at the other side of the blade within the housing. Now you can use a ratcheting wrench with a socket to lose the bolt and nut. And if you observe rust formation on the fastener used, apply a bit of lubricant and wait for 30 – 40 minutes before making progress again. You can also slip a pipe across the wrench handle; this can serve as leverage too.

Sharpening Your Blade with a File

Making your mower blade to be as sharp as a butter knife should be your goal, you don’t need razor sharpness since the blade always spins with speed.

  • Clamp and File

Clamp and File - how to sharpen a lawn mower blade

Using a file is one of the easiest and simple tools to use on a blade, once it is properly secured to a vice. Add some pressure to the file while running it perpendicularly on the blade’s edge, upward and downward ensuring it comes in contact with all imperfection on the metal surfaces. Once you’re done with one part, reposition the blade, and sharp the other side. When compared to the use of hand file, this process is a bit slower, but the essential part is, they both yield the same result.

  • Use a Bench Grinder

how to sharpen a lawn mower blade to using a bench grinder

Using a bench grinder is one of the fastest means to get your lawnmower blades sharpened with less stress. This time you will need to use protective earplugs,

Bench grinders are perfect options when it comes to fixing blades with significant damages, which in most cases, can be difficult to fix if you intend using a hand file.

  • Use a Drill and Blade Sharpening Stone

Use a Drill and Blade Sharpening Stone to sharpen a lawn mower blade

Blade drill bit sharpeners are pretty similar to a bench grinder, but this time they appear a bit smaller in size and affordable when compared to the bench grinder.  It is faster and yields a better result than hand filing. You can hug the stone around the edge of your blade; this makes the entire process easy with less error and more efficiency.

Balancing & the Reinstalling the Blade

Once you’re done sharpening the blade, the next phase is to make sure it’s balanced enough when placing it to the original position. You can use a wrench tool to tighten it up the bolt or nut properly. Now reconnect the wire to the ignition, refill the tank and then take the mower out to test run.

How Often Should You Sharpen Your Mower Blade?

If you use the mower regularly, then you can take out time to sharpen the blade once or twice in a year. While doing this, it is also advisable to oil the surface and joints properly, and also check the spark plug and filter out.

If the machine is heavily used or has lots of sticks, debris, or weeds, sharpening the blade several times in summer will be recommended. If the blade gets blunt easily, you can consider going for another purchase. This will help save time and stress and allow you to sharp the blade only when it’s needful.

The blade of your mower can last for a long time. However, when the mower blade becomes worn out or unsafe, it is wise to discard and replace it with something better. It is vital to go for blade sizes that are in line with the size of your mower. When the blade appears to be cracked, bent, worn out, or deeply rusted –it should be discard and replaced with something new.


Irrespective of the method you decide to use to sharpen your lawnmower blade, the most important factor to bring to perspective is to have your protective equipment that can be used to protect the hands, ears, and eyes. Grinding blades requires a bit of effort, but it’s a task an adult can handle but with proper precautions against accidents.

About the author

Brent Butterworth

A Professional Woodworker & Custom Furniture Builder

Brent lives in Wisconsin and is a woodworker, custom cabinetmaker, interior consultant, and a freelance writer who got the opportunity to write several magazine articles for different publications on home improvement and woodworking. He’s always amazed at the depth and breadth of woodworking all over the globe, and feels proud to be a part of this great effort. Brent has built everything one can imagine, from unique art furniture to different types of home furniture to canoes and even a sailboat.

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