How to Sharpen Lawn Mower Blades – A Definitive Guide

Sharping lawn mower blade is so much essential for every healthy lawn. Because a sharp blade saves time and energy while mowing and always gives you a clean cut. It also helps to minimize the spread of lawn fungus. I think it the best advantage.

A dull blade could not trim the grass efficiently and conflict with the grass’s edge, and sometimes it’s pulling the grass root. It also promotes fungal growth. 

lawn mower blades

As a result, after a few days mowing your lawn, you see an unhealthy brown yard. And no one love to see his/her yard is brown.

How often sharp lawn mower blades?

How to Sharpen Lawn Mower Blades - A Definitive Guide 1

If you want to see a healthy green yard then, our recommendation is, please sharpen your lawn mowers blades at least two times in a year. Also, some manufacturer recommends, sharpen your lawn mower blades after 10 hours mowing.

So, each year before starting the mowing season, sharpen your lawn mowers’ blades properly.

In this article, I covered all information about how to sharpen your lawn mowers’ blades with a step-by-step process.

It can not take much more time from you. If you follow our guidelines, it takes almost 15-20 minutes for one blade with a hand file, but if you are an expert, you can do it with a bench grinder with a few minutes.

So let’s dive into the instruction.

Overview sharpening your mower blades

  • Disconnect the spark plug 
  • Tip mower on its side
  • Remove the blade
  • A sharp blade with a file
  • Proper filing angle
  • Check blade balance
  • Reinstall the blade

How to disconnect the lawn mower spark plug?

How to Sharpen Lawn Mower Blades - A Definitive Guide 2

For safety, first, we need to disconnect the spark plug before removing the blades. If you are using a spark plug socket, you can easily remove the spark plug. For cordless lawn mower – please remove the battery pack and corded lawn mower please disconnect the electric cord extension first; for diesel or gas-powered lawn mower – drain the gas tank carefully so it won’t spill any fuel while you remove the blades.

I think one question comes in your mind why I remove the spark plug when I want to sharpen the blades?

What are the primary reasons?

If you did not remove the spark plug, it’s not entirely safe for you, and you might start your lawn mower by accidentally.

Also, one more thing, please always remind in your mind that when you remove the spark plug, then tape or tie it back, so it doesn’t flop back and contact with the spark plug and start the engine.

Tip mower on its side

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A tip lawn mower is not very hard but strategic. Always tip lawn mower on its exhaust side. And make sure on the side that does not have a carburetor so that the mower’s fuel does not leak out.
Also, make sure the gas and oil caps are screwed on tightly before tipping the mower.

Remove and clean the lawn mower blades

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Now you put your hand gloves and use a socket wrench to remove the blade mounting bolt and keep the blades on your other hand. Also, be careful not to lose any bolt washers or mounting hardware because we will reuse these washers or equipment.

Now you need to clean the blades. Use a rag, and it takes a few minutes to clean the blade before sharpening it.

3 Useful Methods to Sharpen the Blade

  • Hand File  
  • Using a bench grinder 
  • Hand drill and the sharpening stone. 

These are very convenient tools for cutting down the edge of the blade quickly.

Method - 1: Sharpen lawn mower blade with hand a file

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After remove and clean the blades now, you need to determine whether to sharpen it or replace it. My recommendation is to use a flat hand file to do it. A flat hand file is an easy tool that’ll sharpen dull blades quickly.

Make sure that sharpen from the top of the cutting edge; this will give you the longest-lasting edge on the blade.

You are using a vise or a sturdy clamp to hold the blade and apply the medium pressure to the file and run it perpendicular to the edge of the blade. Do it equally on the blade edge and repeat on the other side once you’ve done one side.

Shaping a mulching blade is more difficult because these blades may have longer or curved cutting edge. That’s why you need several types of files. If you think it’s difficult for you to happen, then take it to a hardware store or find a blade sharpening service.

Method - 2: Using a bench grinder - for experts

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Experts are using a bench grinder for sharpening the blade very fasted way.
But the bench grinder often sends the sparks and debris in the air, and it makes so much noise.

For safety, before you place the blade against the grinding wheel, make sure that you are wearing eye-protective, earplugs, and working gloves and long-sleeved shirts. These things protect you from any flying metal and sparks.

Now turn the bench grinder on and double-check to see if you are holding the blade in a comfortable way, that helps you shape your blades lot easier.

Make sure you are posting the blades’ correct angle and move the edge back and forth against the grinding wheel.

Method - 3: Hand drill and the sharpening stone

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Using hand drill and the sharpening stone is another way to sharpen the blades in a few minutes.

It works much like a bench grinder, but it not so fast like the bench grinder but quicker than the hand file.

The sharpening stone of the bit is designed to hug the edge of your lawn mower blade, making it easy to sharpen with minor effort and room for error.

Check blade balanced

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Once both cutting edges have been sharpened, balance the lawn mower blade is the most important thing.

Because an unbalanced lawn mower blades can damage the motor and put undue stress on the mower, it also ruins the blade’s shaft or bearings and makes vibration.

To check the balance, simply drive a nail into a stud, and set the blade onto it like an airplane propeller and see the blade’s stay levels.

Or you can use a lawn mower blades balancer. Make sure that you placed the balancer on a flat surface. Then set the blade on the top of the balanced.

If one side falls, that means it’s more substantial than the other side, and you have to file or grinder more metal off it. It’s a continuous process until the blade stays level.

Paint & Reinstall the lawn mower blade

Once you have done all things correctly now, you need to paint the blade that will protect the blades for the rust. After painting the blade then wait for dry and reinstall the blades. Use a socket wrench to tighten up ta nut or bolt snugly.

After reinstalling the blades, place it back onto the mower in its original position and reattach the spark plug.

Maintenance Your Mower Blade

Regularly sharpening lawn mower blades is a great habit; it’s useful for maintaining a healthy lawn.

  • The end of your mowing time always looks at the grass if the grass has a clean and smooth edge that means your blades are sharp. But if the grass edge is fried or torn, that means your blades probably dull and should be sharpened. 
  • Balanced the blades regularly.
  • If you see any dents or crack on the blades, then please replace it.


All things are transparent, and now you know why sharpening a lawn mower blade is essential, what’s the benefit.

I hope you enjoyed my guide to sharpen the lawn mower blade. Now I want to know which tip from today’s guide do you want to try first and why you will try?

Are you going to try first with a hand file, bench grinder or maybe you want to do it by hand drill and the sharpening stone.Tell me below the comment section.

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