How To Sharpen a Mulching Blade

Your mulching blade might get dull over time and can cause the lawn to look unattractive or cause the mower to lose its cutting quality.

Sharpening your mulching blade will keep your lawn mower in good shape and help to maintain a healthy-looking lawn.

In this article, I reveal 5 common methods on how to sharpen your mulching blades to ensure optimal mowing results on your lawn.

Ready? Let’s dive right into it:

Tools Required For The Job

• A vise
• Plastic balance checker for blade
• Wooden box (optional)
• Lawn mower blade sharpener  (cordless drill, metal file or grinder)
• Hand gloves
• Eye protection glasses

How To Remove a Mulching Lawn Mower Blade

Here are some steps on how to remove your mulching blades:

• Disconnect your spark plug cable to prevent the engine from starting accidentally.
• Ensure that your spark plug is up when you tip or turn the mowing machine upward to replace your mulching blade. In addition, your spark plug should be in the upward position.
• Drain or empty the gas or grass to prevent it from dripping or leaking when you tilt the lawn mower upside down or sideways.
• You can tip the mowing machine towards the front side only if you do not want to drain the grass or gas.
• When you drain/empty the gas and grass, you can see through the nuts that hold your mulching blades that are located underneath the cutting deck.
• Ensure that you snap pictures of the mower blade so that you can know the procedures for installing the blade again after you sharpen it.
• Take off the old mulching mower blade. Use a piece of wood to prevent the blade from turning when you detach your nuts. Make sure that the wood in your mower deck is at an angle of 90 degrees so that you will not bend the blade while taking it off. Another method to try is to hold the blade with your hand and use a wrench to take off your nuts with a wrench.

Note: It is important to have the ideal socket size that is ideal for the nut that holds the blade.

Using the wrong socket size to detach the blade might affect the shape of the nuts. If this happens, it might be impossible to detach your nuts with a socket because the shape will be affected.

• After you have taken off your mulching blade, you need to sharpen it.

Important Things To Know Before Sharpening Your Mower Blade

Here are some important things to know before sharpening your mulching blades:

Do Not Affect Its Design

This is one of the important things to know before sharpening your mulching blades. The design of your mulching blade is pivotal because it can directly affect the performance of the blade. Some mulching blades have serrated teeth while some have curvy flaps.

Do not bend the blade so that you won’t affect its cutting performance on lawns.

Identify the Balance of Your Mulching Blade

The metal may rub off when sharpening your lawn mower blade. In this case, the weight of the sharpened area may be reduced.

If you sharpen one side of the blade, the other side will weigh differently and this can cause the mulching blade to be imbalanced. 

Furthermore, it can also cause the blade to wobble on your mowing machine while mounting it.

To prevent wear and tear on your mower engine, it is important to keep the weight balance of your mulching blades on both sides.

To balance the blade, use a blade balancer or plastic balance to balance it after you sharpen it.

Identify the Part of The Mulching Blade That Requires Sharpening

The cutting edge of the mulching blade should be the part to sharpen. Several mulching blades differ in shape.

Some mulching blades come with serrated teeth while some blades also have simple curved flaps without any teeth. Ensure that you get the cutting edge for sharpening.

How To Sharpen A Mulching Blade With A File

Here are some steps on how to sharpen a mulching blade with a file:

• Get a vise that fits your mulching blade and tighten it so that it can hold the blade firmly from the middle.
• Make sure that you trace the angle on the cutting edge and get the area that requires sharpening.
• Downstroke your narrow file in the same direction as the cutting edge of the blade.
• If you feel the sharpness on your thumb or you observe that your mulching blade is shiny, it means that the blade is sharpened. Make sure that you check the balance.

Using a Bench Grinder To Sharpen Mulching Blades

Here are some steps on how to sharpen a mulching blade with a bench grinder:

• Make sure that you wear eye protection.
• Turn on your bench grinder and carefully push your mulching blade against the disk to sharpen it.
• Ensure that you sharpen it at the right angle. To keep the balance, make sure that you sharpen it from both sides.

How To Sharpen Mulching Lawn Mower Blades with a Sharpening Jig

Here are some steps on how to sharpen a mulching blade with a sharpening jig

• Wear your safety glasses and gloves and turn on your jig.
• Swipe the blade’s cutting edge in the machine so that your blade can be sharpened.
• When sharpening your blade, maintain balance. You are done with its sharpening once you see a shiny cutting edge.

Using a Cordless Drill To Sharpen Your Mulching Blade

Here are some steps on how to sharpen your mulching blade with a cordless drill:

• Put on your eye protection and start the drill.
• Move the drill on the edge of the blade in such a way that the mulching blade will touch the sharpening stone and the plastic guides onto the blade at the right angle and direction.
• After a few swipes, a shiny metal will indicate that the mulching blade is sharpened.
• Ensure that you check the blade and the balance.

How To Sharpen Your Mulching Blade with a Hand-Handled Grinder

Here are some steps on how to sharpen your mulching blade with a had-handled grinder:

• Get a vise that will fit your mulching lawn mower blade. Tighten it down to hold your blade firmly in place.
• Ensure that you follow the line of the blade where the cutting edge is.
• Carefully push the grinder’s moving disc against it
• Ensure that you maintain the blade’s balance while you sharpen it. A shiny metal edge indicates the lawn mower blade is sharpened.
• You should also check the blade’s balance. You can install the blade if the balance is right.

Precautions While Sharpening Your Mulching Blade

Here are some safety precautions to follow while sharpening your mulching lawn mower blade:

• Always make use of gloves and eye protection while sharpening your mulching blades.
• Swipe the sharpening material gently or carefully to prevent it from disturbing the blade’s shape.
• Ensure that your lawn mower blade is well tightened on your vise to prevent it from flying away while you sharpen it.
• Always make use of a narrow file to sharpen your blade. It works better than a wider file.

Do Mulching Blades Come Sharpened?

Some mulching blades come sharpened but this depends on the manufacturer of the blade. 

If you own a 3-in-1 mulching blade, you will be able to discharge the grass, mulch and bag grass clippings on your lawn. These blades have sharp tips for mowing operations.  

Your mulching blades need to be sharp to ensure smooth cuts and to also prevent the grass from getting shredded on the lawn. 

How Often Should I Sharpen my Lawn Mower Blades

It is advisable to sharpen your lawn mower blades after every 20-25 hours of use time. This also depends on how often and how long you mow.

Importance of Sharpening Your Mulching Blades

Here are some important reasons for sharpening your mulching mower blades:

Enhance Attractive and Healthy-Looking Lawn

Dull mulching blades will fail to cut leaves, grass and other debris. You need to sharpen your mulching blades to ensure an attractive and healthy-looking lawn.

Sharp mulching blades can also leave a smooth lawn appearance without leaving any grass stripes.

They will also make it easier for you to drive or push your mowing machine across the lawn.

Prevents Blades From Getting Rust

Your lawn mower blades can get rust when you cut wet grass or you store it in a humid place. You should sharpen it to prevent the blades from getting covered in rust.

Prevents Clogged Mower Deck

The cutting deck might get blocked if you do not sharpen your mulching blades. 

The grass clippings and mulch can accumulate on the deck and jam the mower blades since they cannot cut through the debris. You need to sharpen your blades to prevent this from happening.

Frequently Asked Questions