How to Sharpen a Mulching Blade? All Methods Explained

Share on:

Your blade gets dull over time and loss it’s cutting quality; then it’s time to sharpen it.

When you sharpen a lawnmower blade, you may lose its balance or cutting edges if you’re not a professional. Plus, if you don’t have the right sharpening equipment, how will you do that right.

Getting on “How can you sharpen mulching blades?” I have summarized all methods from my experience. Let’s get into more details:

How To Sharpen Mulcher Blades

how to sharpen a mulching blade

Here are complete details on sharpening the mulching blades for your push mower, self-propeller, walk behind mower, and many more.

Material Required

Steps to Remove the Lawnmower Blade

  • The first thing you need to do is to disconnect the spark plug wire, so there is no way your engine can fire on accidentally.
  • The other important thing is the spark plug should be up as you turn or tip the mower up to replace the blade; the spark plug should be up in the air.
  • Also, it is better to empty the grass or fuel so it might not leak or drip when you tip your mower side to side or upside down.
  • If you don’t want to empty the fuel or grass, tip the mower towards the front only.
  • After that, you will have easy access to the nuts holding the mulching blades under the mower’s deck.
  • Take a picture of the blade or spray some paint on it, so you will know how to install it again after sharpening.
  • Now you will remove the old blade. Here you can use a piece of wood to hinders the turning of the blade when you remove the nuts. But keep the wood in the deck at a 90 degree angle so you may not bend your blade while removing it.


  • You can try another way to remove the blade by holding it with your hand and removing the nuts with a wrench.
The important thing to mention here is the right size of the socket that will fit the nut holding the mulching blade.

If you don’t have the right size socket to remove a blade you might end up rounding them off. It happened to me previously.

In that case, no socket will be able to remove those nuts because you have disturbed their shape.
  • Now you have removed the blade.
  • The next step is to sharpen it.
  • You can use various methods to sharpen the blade.

How to Sharpen a Lawnmower Blade With a File

Sharpening of lawnmower blade with a metal file is the best way and it’s very easy.

A file is basically a piece of metal with a rough surface, and when rubbed against a surface it makes it sharper.

So, we use the file to rub it again our mulching lawn mower blade to sharp it.


  • First, you need a vise in which you will fit the blade and tighten it down to hold the blade securely from the middle.
  • Now trace the angle on the cutting edge where it needs sharpening.
  • Now you can downstroke the narrow file in the same direction as the blade cutting edge is. It is just like you are swiping your credit card.
  • After few strokes, you will get a nice edge on that blade.
  • Once your blade is shiny and feels sharp on your thumb, then it confirms that you have sharpened your blade. Don’t forget to check its balance at the end.

How to Sharpen a Lawnmower Blade With a Cordless Drill

The cordless drill has an attachment that helps you to sharpen your lawnmower blade. That attachment is basically a sharpening stone and a plastic material packed together.

You use this attachment on a drill and sharpen your blade.

Plastic is basically called a guide that keeps the blade at the right angle when you touch it with an attachment drill.


First, wear eye protection and then turn on the drill.

Start moving drill on the blade edge such that the blade touches the sharpening stone, and the plastic guides the drill to move onto blade at right direction and angle.

After swiping a few times, seeing the shiny metal confirms that your lawnmower blade isn’t dull anymore.

Check the balance and lawnmower blade, and you are good to go.

How to Sharpen Lawn Mower Blades With a Bench Grinder

Bench grinder makes short work of it. I personally prefer that to sharpen my mulching blades.

A bench grinder is simply a machine fixed to a wooden bench and has a sharpening disc.


  • First, put on the eye protection.
  • Now turn on the bench grinder and gently push the blade against the disk such that it sharpens it.
  • Make sure that you sharpen it at a right angle and sharpen it from both sides to keep the balance.

How to Sharpen Lawn Mower Blades With a Hand-Handled Grinder

Hand handled grinder is a machine that you can carry with your hands and rub it against a lawnmower blade to sharpen it.


  • First, you need a vise in which you will fit the blade and tighten it down to hold the blade securely in place.
  • Now follow the line of the blade where the cutting edge is.
  • Gently push the moving disc of the grinder against it.
  • Make sure to keep the balance while sharpening it. Once you have a nice shiny metal edge, it confirms your blade is sharp.
  • Check the balance of the blade; if it is right, then you can reinstall it.

How to Sharpen Lawn Mower Blades With a Sharpening Jig

A sharpening jig is basically a wooden assembly that is just like a bench grinder, but the difference is the design and structure of its parts.

It has a middle portion where you swipe your blade gently to sharpen it with the moving disc.


  • Simply put on the safety gloves and glasses and turn on the jig.
  • Now swipe the cutting edge of the blade in the machine so it can sharpen it.
  • Maintains the balance while sharpening it, and you are done once you see a shiny cutting edge.

Installation of Mulching Blade

After sharpening the blade, you install the blade right away.

Many people get confused here that

How do you know if mower blade is upside down?

The best way to know that is to keep in mind that when you install it, keep the serrated teeth or curvy flaps towards the mower's deck and cutting edges points towards you. It won't be so hard to install if you have taken the pics already, as I told you in the procedure.

Precautions During Sharpening of a Lawnmower Blade

  • Always use eye protection and gloves while sharpening a lawnmower blade. The chances of injury are quite low as 1% but wearing protection is a good practice.
  • Always swipe the sharpening material on a lawnmower blade in a gentler way so it may not disturb the shape of the blade.
  • Never place wood on any angle other than 90 degrees to restrict the blade movement when you unscrew the old blade.
  • Make sure the mulching blade is tightened well on the vise so it may not fly away while sharpening it.
  • Never use the tools to pull the spark plug wire, always pull it by hand.
  • Always use the narrow file to sharpen the mulching blade as it is more efficient than the wider one.

Important Things to Know Before Sharpening

Try Not to Disturb the Design

First, the most important thing you need to know is that the mulching blade has a design that directly affects its performance. The design includes serrated teeth or curvy flaps.

Try not to disturb the design or bend your blade because it will lose all its working features.

Know the Balance of Blade

When you are sharpening the blade, you are actually rubbing the metal off, which will decrease the weight from the side where you are sharpening it.

So, if you have sharpened the lawnmower blade from only one side, the other side will have a weight difference, and eventually, you will lose the balance of the blade, and it will wobble on the mower once you mount it.

So, keep the weight balance of the blade on both sides well to avoid wear and tear of your mower’s engine.

Here, another question comes to mind:

How do you balance a lawnmower blade after sharpening it?

You can use plastic balance also called blade balancer to know the balance of the lawnmower blade after sharpening


To know the balance, you can put a nail on a wall and hang your blade on the nail. If your lawnmower blade keeps its balance on both sides after hanging, you are good to go.

How Would You Know You Have Sharpened Your Mulching Blade?

After you have sharpened your blade, install it on your mower and mow doing one pass on your lawn.

After that, check the grass closely. If the grass has a nice clean cut like they are whipped by a sharp knife, then congratulation you have sharpened your mulching mower blade.

But if the grass is ragged on the top then you haven’t sharpened it well.

Ragged means uneven cut which you should avoid for two reasons

  1. Disease can get into grass and kill your lawn grass
  2. Few days after mowing, your lawn will have a brown cast to it which not going to look so good

How Often Should Mulching Blades Be Sharpened?

You can sharpen the mulching blades right before first mowing after installing your lawnmower blade, or you may not sharpen at all because some mulching blades in the market come already sharp in the box.

But after you have installed the blade for the very first time, your mowing abilities will decide when will you be doing the next sharpening of the mulching blade.

For example, if you are mowing on thick grass more occasionally then you will need to sharpen so your mower gives uniform chopping.

And if you have hit it with some solid subject, you will need to sharpen it, or it may require some recovery from bending if you got it bent after hitting something like stone.

Which Part of the Blade Should I Sharpen?

That’s another question that came to mind that you may have. It’s pretty much simple if you know the cutting edge. Because there are two kinds of mulching blades according to their shape

  1. Mulching blades having serrated teeth’s
  2. Mulching blades having simple curved flaps without any teeth’s

In both cases, the basic idea will be the same that you just have to sharpen the cutting edge nothing more than that. Don’t get confused with sharpening the teeth also as it may result in overall de-shaping of blades and zero-performance.

Frequently Asked Questions

Should you sharpen mulching blades?

You should sharpen a mulching blade when its cutting edge gets dull or giving ragged (uneven) cuts because ragged cuts can lead to diseases and brown casting on your grass.

Are mulching blades supposed to be dull?

Mulching blades can be dull even if they are brand new, but that doesn’t mean they won’t perform well on the grass as I have tried dull Gator blades on my lawn without sharpening, and they worked fine. So, a brand-new blade doesn’t need to sharpen in many cases. If a mulching blade gives a clean cut on the first try, then there is no need to sharpen it.

Can you sharpen a lawnmower blade without removing it?

The hard answer is YES, but it is best practice to sharpen the mulching blade after removing it for your own safety and time. If you really intend to sharpen it while it’s still mounted on, then use a metal file without pressurizing the main shaft, as it can disturb the engine parts or the working of your mower.

Should mulching blades be sharp?
Absolutely yes, the mulching blade should be sharp because a sharp blade is only going to give a nice cut and smooth lawn without leaving any grass stripes where a non-sharpen blade can cause clumping and clogging of your lawn mower chute.

Can you sharpen mulching blades?

You can sharpen a mulching lawnmower blade with a file or angle grinder or using the sharpening jig. It’s the best idea only to sharpen the mulching blade if you know the detailed producer and safety measures you should follow.

Do you sharpen both sides of a mower blade?

It is recommended to sharpen a lawnmower blade from both sides as it will maintain the balance of the blade. After you install a well-balanced blade on your lawnmower, it will not cause any vibrations or wear and tear.

Do brand new mower blades need to be sharpened?

Sharpening of brand-new blades isn’t required in most cases as they already come sharp. For example, brand new Gator blades already come sharply in the box. Some blades may require sharpening if you are about to mow on thick grass.

how sharp should a lawnmower blade be?

The lawnmower blade should be sharp enough to give a nice clean cut on grass. Keep in mind that lawn mower blades shouldn’t be razor-sharp to cut your hand. Your blade is sharp when it gives you even cuts on grass.

What is the correct angle to sharpen a lawnmower blade?

You can have the correct angle if you use a metal file in the same direction as the cutting edge is. Mostly the angle will be around 45 degrees. However, the sharpening angle should be such that it doesn’t disturb the design of the blade, which you will only know while looking at it.

When should I replace my lawnmower blade?

When your lawnmower blade is giving the ragged (uneven) cut, then you should replace it. Ragged cuts can easily be observed on fresh-cut grass.

Does Ace sharpen mower blades?

The ace sharpener works fine on many lawnmower blades. It has a sharpening stone and plastic packed into one, and you can mount it one drill to sharpen your lawnmower blade.

Can you use a Dremel to sharpen a mower blade?

Dremel 675 is a proven mower blade sharpener. It’s a gardening tool that sharpens the lawnmower blade at a precise angle.

How do you sharpen a lawnmower blade by hand?

If you intend to sharpen a lawnmower blade by hand, you can use hand-handled tools like metal files, cordless drill attachments, and angle grinders.

Photo of author


After doing my master’s in agriculture, I went on with this field for more than 15 years because I love working in green. I have experienced using modern machinery and techniques that can help farmers and landscapers to achieve something great. My goal will be to deliver you the best reviews and information to make the right decision.

Leave a Comment