How to Sharpen Lawn Mower Blades – Full Guide

Lawn Mowers are one of the most required tools when it comes to lawn mowing. They are used to chop, trim or mow the grass strips at a particular height, giving your lawn a smooth and well-groomed look.

But how can you make your mowers maintain its best trimming performance seasons after seasons?

Just by your little effort of sharpening the mowers blades when required.

Dull mower blades can give an uneven trimming, leaving behind unmowed grass strips here and there. And you have to redo your job, which makes your mowing challenging.

Thus, it would be best if you had a Lawn Mower with well-sharpened blades to maintain a perfectly trimmed lawn, which gives rise to a question.

How to Sharpen Lawn Mower Blades?

The process of sharpening can be done either by removing the blades or by letting the blade attached to the mower. However, sharpening without removing is not as popular as the former method. But it saves time the extra time and hassle of removing and attaching the blade.

So, in this article, we are going to discuss the entire process of sharpening the Lawn Mower blades without removing it.

Tools you require

  • Grinder or grinding wheel to file the blades
  • Safety glass and gloves for protection
  • Wire sponge and steel wool for cleaning the blades
  • Two wooden blocks to hold the machine in position during sharpening

Course of Actions

The method employed for sharpening the blade is almost as the process filing the blade after removing it from the mower. But in this case, you must be careful to follow the tips, or the outcome may not be up to par.

The procedure of sharpening the Lawn Mower blades without removing can be split into a few simple steps.

Wear Safety Glasses and Gloves

When the grinding wheel touches the blades at a fast pace, sparks come flying out during the entire process. So, it can be dangerous to sharp the blades without the safety glass and gloves. And as getting hurt, it is the last thing you would want so, don’t forget to take precautions.

Disconnect Lawn Mower from the Power Source

Before starting, make sure you have disconnected all possible power sources of the mower. It prevents accidental starting up of the blades in case of any user’s mistakes or mechanical failure.

For a gasoline-powered Lawn Mower, make sure to take off the spark plug wire out. In the case of a battery-powered mower, disconnect it from the battery. Or, if you have electric mowers, remove it from the electric outlets before starting with the sharpening procedure.

Tilting the Lawn Mower

Lawn Mower Blade SharpeningSharpening without removing the blades can be challenging if you can’t access the blades properly. Thus, to get comfortable and full exposure to the blade of the mower lay the Lawn Mower on its side.

In the case of a gas mower, don’t forget to empty the fuel tank before tilting the mower. It prevents the leaking of the fuel, causing its loss. Furthermore, make sure to lay the mower in such a way that its carburetor faces upwards. It prevents the tripping of the remaining oil, and you won’t notice a smoke cloud the next time you use the mower.

Secure the Positions

During sharpening, any tottering of the mower or its blades can make the filing process problematic. Even instability of the mower can lead to injuries.

So, before starting to file the blades, put a wooden block under the motor to prevent its stumbling during the process. In case you are using a hand grinder, for additional stability, you can also secure the blades to its positions using another wooden block.

Clean the Blade

Before you start filing the blade, it is necessary to get full access to its cutting edges. For that, be sure to clean the blade thoroughly with the wire sponge and steel wool. It removes the rusting, debris, and caked grass from the blade, exposing the cutting edges for better sharpening.


The final and crucial step is sharpening. Whether you file it manually with a grinder or use a grinding wheel, make sure to hold the tool angled towards the grinding wheel. A 45-degree angle offers the best sharpening result.

Moreover, if you prefer hand grinder, try to stroke the cutting edges uniformly without giving a backward stroke. This gives the blade a balanced-cut on both sides of the center.

An unbalanced blade can give a poor cutting even if it is greatly sharpened. Also, check that the center hole is not wallowed out, giving it an unhinged attachment to the deck. Moreover, your mower may generate weird noises while working if the blades remain unbalanced.

Frequently Asked Questions

How sharp should the Lawn Mower Blades be?

The mower blades should be sharp enough to give a clean trim to your lawn. For that purpose, you don’t need a razor-sharp edge. A simple butter knife sharp will do such that you don’t cut your hand while checking its sharpness.

Moreover, a razor-sharp blade will show the tendency of rolling over, causing the blades to get nicked and scratched all over. This also makes the blade life shorter.

How often to Sharpen Mower Blades?

The frequency of the sharpening of the blade depends upon its usage. For example, if you need to mow a small volume of grass, the frequency will be far less than when you mow thick overgrowths. On average, you can sharp the mower blades after every 20-25 hours of its use time.

How many times can you Sharpen a Mower Blade?

The Lawn Mower blades can be sharpened 5 to 8 times before it needs a replacement. But the high-quality blades can be sharpened for around 16 to 20 times before they get unusable.

Do you sharpen both sides of a Lawn Mower Blade?

Mower blades are specially designed to build upward suction of the grasses for the ease of mowing. If the blade is sharpened on the bottom side, this function gets disturbed, causing an uneven mowing of your lawn.

How long do Lawn Mower Blades last?

The lifetime of the blade partially depends on how well it is maintained. But on an average, most Lawn Mower blades have a lifetime of sound 100-200 hours, while the branded one can last as long as 400 hours.

How do I know if my Mower Blade is dull?

Look at your lawn for the hint. A dull mower blade causes the grass to tear apart instead of cutting and leaves behind unmowed strips of grass. Moreover, the mowed strips get uneven cuts and turn into brown shade due to its tearing. It indicates that your mower blades need sharpening.

When should I replace the Mower Blades?

At some point, your blades get beyond the point of resharpening and need replacements. You can get the hint after a visual scan of the blades. You will notice nicks and chips all over the blade along with its reduction in thickness, which indicates its erosion.

If you are using the mower for residential purposes, the replacement of the blade once a year will be enough.

Check out: Best High Lift Mower Blades

Does cutting wet grass dull the Blades?

Wet grass dulls the mower blade with the same speed as the dry one. But the damp lawn has the grass bend with water droplets causing the mowing difficult. Further clippings of wet grass clog and chock the mower, causing difficulty in mowing.

Will a dull Mower Blade kill grass?

When the blades get dull, instead of cutting the grass, it tears them apart. This causes discoloration and ragged looking grass. These grasses are more prone to attract diseases and may die.

When grass is neatly cut, it can recover quickly, which minimizes the risk of lawn diseases.

Should I remove the Blade before Sharpening?

Removing the blade and sharpening them is easier and effective, as you get the full access to the blade without any difficulty. But few people prefer sharpening without removing as it minimizes the steps of removing and installing the blades, thus saving time.

You will need a Lawn Mower Lift in case you have a Riding Mower.

Over to you

This was a quick guide on how to sharpen your Lawn Mower blades, and if you have any questions or suggestions, you’re most welcome to write them down in the comments section. Stay tuned I am going to share more guides here in the upcoming days.

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