How to Sharpen Lawn Mower Blades (Step By Step Guide)

People often consider the appearance of their yards a matter of pride.

Certainly, a well-kept lawn cannot be managed without regular mowing.

It will not only give your lawn an orderly look but it will also help maintain the health of your grass.

While it is significant to mow your lawn regularly, it is also extremely important to mow your lawn using a lawnmower with sharp blades.

Dull blades can damage the grass and leave behind torn ends on the tips of the individual grass blades.

This can expose the grass blades to diseases and pests.

It will also leave the tip of grass blades brown the next day.

On the other hand, sharp lawn mower blades will help you cut the grass neatly and quickly without damaging it.

In this guide on how to sharpen lawn mower blades, we provide tips for how sharp the blades should be and how frequently you need to sharpen them.

We also share insights on whether to sharpen the blades or replace them to maintain the health of your lawn.

In the end, there is a step by step guide on how to sharpen lawn mower blades.

Using these steps, you will learn that working with lawn mower blades is not as challenging as it may appear to be.

The tips highlighted in this article will surely help you better understand the needs of your lawnmower blades and maintain a beautiful, healthy lawn.

How Sharp Should Your Lawn Mower Blade be?

We all know that lawnmower blades should be sharp. But just how sharp is sharp enough?

Contrary to popular belief, lawnmower blades should not be razor-sharp.

Instead, they should be sharp enough that you are able to touch it without cutting your hand.

Lawnmower blades which are razor-sharp will not cut the grass effectively.

This is because such blades can rollover.

This can result in chipping of the blades.

Also, excessively sharp blades need to be sharpened more frequently because they can quickly become dull.

They also have a shorter blade life. 

How Often Should You Sharpen Your Lawn Mower Blades?

Now that you know how sharp lawn mower blades should be, the next important question is how often you should sharpen your lawnmower blades.

The answer really depends upon the frequency of use.

If you only use the lawnmower at home, then sharpening the blades once a year is enough.

But if you are a professional, then you will need to sharpen the blades more often. In that case, the frequency can be as high as once or more every week.

How to Know if your Mower Needs Sharpening?

The easiest way to find the answer to this question is by looking at the grass after you have mowed the lawn.

If the cut is uneven, or the grass turns brown the next day, it’s about time that you should sharpen your lawnmower blades.

Sharpen or Replace?

Just like all other household items, lawnmower blades have a certain blade life.

While regularly sharpening the blade can help you maintain your lawn, the blade will show various signs when it needs to be replaced.

If you notice a vibration in the mower, it is important to check the blade.

Often, damaged blades can cause vibration in the lawnmower.

The blades can also crack, bend, or chip. If this is the case, sharpening the blade will not help. Instead, you will need to replace your blades.

Step By Step Guide For Sharpening Lawn Mower Blades

Lawnmower blades can be sharpened manually using files, chisels, and punches.

But for more effective sharpening, it is best to use a grinding machine.

Getting Started

Sharpening the lawnmower blade is easy and you will only need a few basic tools.

So let’s get started with how to sharpen lawn mower blades using a grinding machine.

Safety Gear

Before you get started, ensure that you have proper safety gear.

You will need protective eye goggles.

If you are using a grinding machine, you will also need earplugs.

Also, make sure you have handled the blade after you put on the gloves.

Inspect the Work Area

Once you have gathered the safety gear, check the work area.

Make sure the area is free from all flammable material such as gas cans, shop rags or any other flammable material.

Also, ensure that no loose objects are positioned close enough to the grinding wheel or else they can get caught in the wheel.

Inspect the Grinder

Do not operate the grinder if:

• There are any breaks in the insulation of the power cord or there are any exposed wires.
• The cord’s terminal is broken or damaged.
• The stone is cracked or chipped.
• Any guards of the machine are missing.

Also, check the position of the top and bottom guards of the grinder before you start the process.

Make sure that the tongue guard installed on the top of the grinder is positioned no more than ¼ of an inch away from the stone.

Also, inspect the position of the bottom guard. Ideally, it should not be positioned more than 1/8 of an inch away from the stone.

In case the guards are not adjusted at the appropriate distance, loosen the nuts which hold them, adjust the position of the guards at the proper distance and then fix the guards again.

Once you have thoroughly inspected your grinder and workplace and have arranged adequate protective gear, you are ready to sharpen your lawnmower blade.

Remove the Blade

The first step is to remove the blade.

In case of an electric lawn mower disconnect the spark plug and the power source.

This will help prevent the motor from starting accidentally.

If you have a cordless lawn mower, make sure you remove the battery.

Then turn the lawnmower on one side.

The side with the carburetor and air filter must face upwards to avoid the spillage of oil or gas.

In the case of oil, you can transfer it to another container or continue to run the mower until it is out of gas.

Now you can remove the blade using a wrench.

Loosen the nut/bolt and turn it in a direction to remove the blade.

It is essential that you take a mental note of the placement of the blade before you remove it.

Blades that face downwards as you remove them will need to be replaced with the same orientation. 

A mistake in the installation of the blade can significantly affect its performance. 

Once you remove the blade, inspect your blade thoroughly. If the blade is extensively damaged, is severely bend or is chipped, you might need to replace it.

If you are not sure whether to sharpen or replace the blade, contact a professional.

Secure the Blade

If you are using a table vise to sharpen your blades, secure your blade in the vise parallel to the ground. As mentioned earlier, check the distance between the blade and the stone.

In case of inadequate distance, adjust the distance. 

Sharpen Each Side

Before you actually sharpen the lawnmower blade, don’t forget to wear safety goggles, earplugs, and a respiratory mask.

For the most efficient sharpening of blades, ideally, you should use a medium stone.

A stone that is too fine or too coarse is not as effective as a medium stone.

The angle between the grinder and the blade should not be more than 40-45 degrees.

Move the grinder at a moderate pace and apply even pressure all over the blade.

Very often, people only sharpen one side of the blade.

This is a mistake that can affect the efficiency of your lay mower blades.

Always remember that once you have sharpened one side of the blade, you have to repeat the process on the other side as well.

In case you have secured your blade in a table vise, you can loosen the nut and rotate the blade 180 degrees.

If you have more than one blade, you can repeat the same process with each side of each blade.

Always remember that you need to sharpen the blade enough that you can touch it without getting your hand cut.

A blade that is too sharp can damage your grass.

Balance the Blade

While a sharp blade is essential, for optimal performance, it should also be balanced.

A blade that is not balanced can cause your lawnmower to vibrate.

In some cases, it can even crack the deck of the lawnmower.

You will need a blade balancer to balance the blade or you can do it manually.

Replace the Blade on the Mower

Once your blade is sharpened and balanced, simply place it back in the same way as you removed it. Insert the bolt and tighten it.

Ready To Sharpen Lawnmower Blades?

Now your lawnmower is ready to give your yard a healthy and orderly look. Remember that this is just a guide and not a substitute for instructions outlined in the manual.

So don’t forget to read and understand the owner’s manual for lawn movers (along with this guide) before you get started with sharpening the lawnmower blades.