Why sharpen mower blades. Do Brand New Lawn Mower Blades Need to be Sharpened

Should You Sharpen new blades?!?!

How to Sharpen Mower Blades for a Better Lawn

Have you ever mowed your yard, expecting it to look great, only to notice the tips of your grass turning white or brown a couple of days later? Maybe your mower has left whole clumps of grass in its wake. These are just a couple of telltale signs that your mower blades have gotten dull.

Thankfully, The ROP Shop is here to help. In this article, we’ll share why it’s important to keep your blades sharp, how to recognize when it’s time to sharpen your blades, and how to get it done.


When you mow with dull blades, you’ll wind up shredding the grass rather than slicing it. This lengthens your lawn’s healing time after each cut. During that recovery time, your grass is more susceptible to pests, drought, and heat.

If you keep cutting with dull blades, your lawn could eventually just give up. As a result, you’ll see discolored spots where the grass has started to die, making your lawn look less like a lush carpet and more like a patchwork quilt. Avoid this headache and pay attention when you mow; you might already be seeing red flags and just not know it.


Your lawnmower’s cutting edge should slice cleanly through each blade of grass, providing an even cut and causing minimal damage. However, if that cutting edge is blunt, it’ll tear the lawn. When that happens, you’ll have shredded grass which turns white or brown at the tips. If your mower blade is dull enough, it can even yank whole clumps of sod out of your lawn, roots and all.

If you notice that your lawn has an uneven, jagged finish, this is also a sign that you may need to look at your blades. It’s possible that they’ve dulled unevenly so that one side of your mower cuts better than the other.

Finally, take note of whether it feels like there’s something wrong with your lawnmower. Does the engine seem like it’s struggling? Has your mowing time increased? If so, don’t schedule with a mechanic just yet. Check your blades first. You might just avoid a bunch of unnecessary troubleshooting.


If you’re seeing any of the above red flags, put mowing on pause and take a look under the deck. If you have a push mower, empty the gas tank or run your engine until the tank is dry, then disconnect the spark plug and tip it onto its side, keeping the carburetor and air filter pointing up.

Inspect the blade. If it looks bent or warped, or if the cutting edge is missing chunks, it’s time to replace it. But if there are only a couple of minor nicks, you should be good to sharpen it up and save a few bucks.


Before you start sharpening your mower blade, be sure to wear the proper safety equipment. At the very least, don a pair of work gloves and some safety goggles.

Once you’re ready to sharpen your blade, remove it and secure it in a vise. If you’re doing this the old-fashioned way with a file, press the file firmly against the blade, matching the angle of the cutting edge, and sharpen it in a single direction. Don’t drag the file back and forth, and don’t sharpen any areas aside from the cutting edges on either end. After every ten strokes, test the blade with your hand.

If you’re using a drill-powered blade sharpener, place the grinder over the blade’s edge. Be sure that the grinder’s guide (the flat piece) is against the back side of the blade and that the cutting edge is in between the two pieces of the grinder. With these sharpeners, you don’t have to worry about finding the right sharpening angle since they adjust automatically. Shift the grinder back and forth across the blade’s edge four or five times with moderate pressure. Then test the blade against your hand. 1

Your freshly sharpened blade should feel about as sharp as a butter knife and shouldn’t break the skin. If you sharpen your blade too much, it will become too thin and will dull more quickly.

When you re-install your freshly sharpened blade, make sure the angled side faces up toward your mower deck. If you install the blade upside down, it won’t cut properly.

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Lastly, before tightening the blade down, make sure it’s perfectly centered and balanced. Mowing with imbalanced blades can stress your engine and harm your mower deck. A couple of ways to know if your blades are imbalanced is if you’re experiencing a lot of vibration when you mow or if patches of grass on one side of the mower look worse than those on the other side. 2

How often should you sharpen your mower blade? It can vary depending on how often you mow and how long it takes you. However, at The ROP Shop, we generally recommend that you sharpen your blades around every 20-25 hours of use.


Now that you know the dangers, warning signs, and ways to sharpen dull blades, you’re well-equipped to keep your lawn and your lawnmower in great shape.

But you never know what life’s going to throw your way. It’s always a good idea to keep a couple of spare blades on hand just in case. Check out our selection below. Be prepared, and stay Rugged.

Do Brand New Lawn Mower Blades Need to be Sharpened?

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My new lawnmower just arrived, but the blades don’t feel sharp enough to start mowing my lawn.

So I’m wondering, do brand new lawnmower blades need to be sharpened, why aren’t brand new lawnmower blades sharpened, and what is the right method to sharpen lawnmower blades.

I’ll also delve deeper and discuss how to know when lawnmower blades are dull, and when it’s time to replace lawn mower blades.

So, do new lawnmower blades need to be sharpened? The brief answer to this question is no, it’s not necessary to sharpen brand new lawn mower blades. New lawnmower blades aren’t dull, and are ready to use right out of the box. However, just like a knife, every homeowner should be aware that lawnmower blades should be sharpened regularly to cut grass at the right height.

Do Brand New Lawnmower Blades Need to be Sharpened?

You don’t have to sharpen new lawnmower blades, because they are already sharpened according to manufacturer specifications at the factory before being shipped.

The myth of sharpening brand new lawnmower blades stems from the fact that new blades appear dull, but the blades of these lawn power tools are pre-sharpened to a point where they can cut grass, but not cause injury to you.

Even though lawnmower manufacturers sharpen the blades for your safety, you can go ahead and sharpen them if you feel there’s a tangible difference in the quality of the cut.

When do Lawnmower Blades Need to be Sharpened?

Wondering when lawnmower blades need to be sharpened? Is it after a couple of hours of mowing or once or twice during the mowing season?

DON’T Use This to Sharpen Mower Blades!! USE THIS INSTEAD

The good news is that you don’t have to sharpen lawnmower blades after mowing, but a rule of thumb is roughly after 20-25 hours of mowing or when they get dull.

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Your lawnmower blades should be sharpened at the beginning of each new season, and more often if you have a large lawn.

Will Sharpening a New Blade Cause Damage?

Each time you sharpen a lawnmower blade, you shave some of the metal, which affects the life of the blade. If you buy a new lawnmower or install replacement blades, use the mower for at least 25 hours before sharpening the blades.

Clues that Your Lawnmower Blades are Dull

Uneven Cuts

Blades over time get dull due to wear and tear, and one of the most glaring signs of dull lawnmower blades is when they produce uneven cuts.

Pay attention to the grass when mowing, and if you notice the grass is somewhat chewed or if it’s covered with brown tips after a day or two, your blades are dull and could benefit from sharpening.

Examine the Blades

Tip the mower over to examine the blades, but with the carburetor side facing the sky (for a gas mower to prevent gas spill).

With safety gloves on, run your fingers along the blade, and if you feel any large indentations or gouges, your blades need to be sharpened. A damaged blade should be replaced with a fresh blade.

Can I Use a Lawnmower Blade Even if it’s Dull?

Well, can you use a razor blade if it no longer cuts your hair? Similarly, a dull lawnmower blade will not cut your grass to the right grass height or probably won’t cut the grass at all, and can also affect the visual appeal of your lawn, and the health of your turf.

The ragged edges of the grass caused by dull blades encourage disease and parasites to enter the grass, so mowing with dull blades is possibly the biggest mistake homeowners make.

Plus, the dull edges of the mower blade will pull at the grass, leading to torn blades rather than smoothly cut blades.

These grass clippings will also momentarily cling onto a dull blade before they rip or tear, which causes unnecessary stress on the mower and can lead to the short service life of the tool.

Benefits of Cutting Your Grass with Sharp Mower Blades

There are myriad benefits of using sharp blades to cut grass:

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How to Sharpen Lawn Mower Blades

When you mow your lawn with the dull blade of your lawnmower, your grass can turn brown due to the ragged cuts. For this reason, it is important to have sharp lawnmower blades. It can keep the grass healthy and green and the mow will also last longer.

All you have to do is to sharpen the blade to have clean cuts. In doing so, your lawn mowing time will be reduced and the grass can recover quickly. Here we shall explain to you how to sharpen the lawnmower blade safely.

Requirements –

The tools required for sharpening lawn mower blades are socket wrench or ratchet set, vise, bastard-cut mill file, and rags. The materials that you require will be work gloves and WD-40 lubricant.

When To Sharpen Your Mower Blade?

When you cut the grass, the nutrients will return to the lawn so that there will be strong and green-looking grass. For this, it is important to provide clean cuts. You can offer a clean cut with a sharp mower. However, with regular use, the lawnmower blade can become blunt and dull. It is important that you inspect the blades from time to time.

  • When there are worn-out blades, you will have to remove them and hone the edges.
  • It is advisable to sharpen the mower blade at least twice a season.
  • Some people often tend to sharpen the blades after 25 hours of use.
  • You will also have to sharpen them when the blades hit rocks which can cause dents.
  • At times you will find it difficult while mowing, where the lawn will give you hints that the blades are dull.
  • You have to look out for different signs like uneven grass height, dents or nicks, torn-looking blades, or frayed grass edges.

Removing and Cleaning Blade

To sharpen the blade, you will have to safely remove the blade from the lawnmower. It is always advisable that you disconnect the power source or battery. Always disconnect the spark plug wires. It helps to protect from any kind of shocks due to power. You can do it in the following way:

  • For better safety, you can wear protective eye gear and gloves.
  • Firstly, always drain the gas tank which will help to prevent fuel spills. You need to turn the mower on its side carefully. However, make sure that the carburetor and air filter are on the upward-facing side.
  • Use a permanent marker or a grease pencil to mark the bottom of the blade. In doing so, you will be able to install it right side up after sharpening the blade.
  • Now you will have to look out for the nuts. By using a wrench or a socket, you can easily loosen the nuts to release the mower blade. Apply more leverage if the grip is very tight. You need to clamp the blade and brace it with a piece of scrap wood.
  • If in any case the threaded shaft and nuts are stuck together, you will have to apply penetrating oil. Always allow it to sit in for a couple of hours.
  • Before sharpening, you will always have to clean the blade with a microfiber cloth or a dry rag. At times you may find the blade to be covered in grass clippings where you will have to use penetrating oil. Allow it to sit for some time and then scrub the debris with a stiff brush.

How To Sharpen Lawn Mower Blade?

To prepare for cleaning, you will have to gather the tools. You will first have to confirm if the blade is damaged or dull. Keep in mind the opposite sides of the blade have a cutting edge of up to 4 inches. To examine the blade, you will have to clamp the mower blade onto a worktable. Keep the cutting edge facing upwards. Look carefully for the signs if it requires sharpening or replacement. A replacement has to be done if the blade has cracks or if it is severely bent. If the blade is dull or chipped, you will have to sharpen it.

The lawnmower blade sharpening can be done in multiple ways. To sharpen it with the hand you will require abrasives or metal files. If you are looking to sharpen it with a machine, you will require a bench grinder, angle grinder, or blade sharpener.

While sharpening you will have to do it safely so that it will not cut your finger. If it is a razor-sharp blade, the likelihood of becoming dull is even more. It is advisable to go for replacement rather than have constant sharpening.

Sharpening by Hand

Always begin by wearing protective gloves and eye gear. You will have to protect yourself from metal shavings and sparks.

  • Use a grindstone or a file of 10 inches to sharpen the blade’s edge. You need to keep the file approximately about 45 degrees.
  • Begin by sharpening from the top side.
  • You will have to push the file in one direction without sawing back and forth.
  • While filling, you will be able to feel the file teeth. When there is no such feeling, you will have to apply a little pressure.
  • Try to reach rough spots and follow the blade edge’s angle. Do note that most blades require sharpening in less than 50 file strokes.
  • After finishing one edge, you will have to release it from the vise.
  • Repeat the process by turning it over to the other side.

Sharpening with Blade Sharpener

Here also you will have to put on gloves as well as hearing protection.

  • You will have to begin by clamping the blade into a vise.
  • Take a standard drill and insert the blade sharpener into it. The blade sharpener comes with a grinding stone that has a beveled edge. It also features a shank of 0.25-inch and a guide piece.
  • Begin by pulling the drill trigger to start it.
  • You can now place the grinder on the mower blade. To have the right sharpening angle, you must keep the flat guide against the blade rear. Also, the cutting edge must slot into the bevel.
  • By applying medium pressure, you will have to move the stone back and forth. Check the blade after every five strokes. It has to be free from any rough spots or nicks and must be very sharp.
  • Complete the edge and then turn the blade over. Begin the process and sharpen the other edge.

When you happen to use a power sharpener, never overheat the blade’s edge. If it is ho,t you can dunk it in a bucket of water.

Sharpening with Angle Grinder

To begin with, you will always have to wear safety gear like ear and eye protection and work gloves.

  • Clamp the blade by using a vise. For the angle grinder, you can use a flap disc.
  • It is advisable to align the mower blade cutting edge with the grinder’s blade.
  • You need to move the grinder slowly against the edge of the blade.
  • Try to do it on the existing edge and make sure there are no rough spots.
  • After completing one edge, you can repeat it by turning it over.

If you feel that the sharpening is complete, you can always check it. Get a piece of paper or a blade of grass and it must cut easily.

Check Blade Balance

Before you install the blade, it is important to confirm the blade balance. An unbalanced blade can lead to vibrations that can damage its components. A well-balanced blade will have smooth running. Any imbalance can even damage your mower and you will have to look for a replacement. There are even ways to check the blade balance by using a blade balancer. You can confirm it in the following way:

  • You can begin by supporting the blade like a scale and using a screwdriver. Now insert the tip of the screwdriver in the blade’s hole. You will find that the blade will balance or drop on the handle.
  • Holding the blade horizontally, you must let it go. In this process, keep in mind that it should remain level.
  • The primary sign of an unbalanced blade is that the blade drops at one side.
  • It can even happen that the depth side is heavier. You will have to remove some metal by taking off a few strokes.

Reinstall the Blade

Reinstalling the blade is a key factor in determining the overall performance. If it is under tightened, then it will make the mower hard to start. During this process, you can easily clean the bowl around the blade. Make sure that you like the area clean which is under the mower. Remove any grass clippings or mud by using a putty knife or scraper.

  • Begin by inserting the blade onto the bolt. Do note that the marked side must be upward.
  • By using a socket wrench, you can tighten the nut. It has to be secure and must be extremely tight so that the mower can start smoothly.
  • You can now connect the spark plug wire as well as the power source.
  • In the next step, you must refill the gas tank.
  • To prevent any fumes, you will have to roll the mower outside the shed or garage.
  • Finally, you can see if the mower starts smoothly.

How to Maintain Your Mower Blade?

Blade maintenance is an important thing for or perfect lawn. You will have to sharpen your blade at least twice during the mowing season. It can provide a healthy lawn and your mower will be in good shape. It does mean that you will have to keep good attention to the blades. You will have to sharpen the mower blade every time you have used it for up to 25 hours. For this, you can calculate the time you have mowed in a season. By keeping sharp blades, you don’t have to worry about getting a new one. In doing so, your blade can last longer.


We have discussed how often should you sharpen your blades. It is very important to sharpen the mower blade. Sharp blades offer clean mowing and can save you money. It can last very long when there is proper maintenance. You will have to look for any signs which can actually compromise the performance of the mower. However, you must maintain safety while sharpening the mower blade and do it carefully.

One Response

Hi, I really liked the articles on sharpening lawn mower blades. But I have come up with a question. I have a lean mower with two blades. So when I put them back on how do they need to go back on? I mean like should they be placed like this – – or || or — l. Not sure how to explain it. Do the blades both face like on a clock 9 to 3 or do I place on blade at 9to3 the other at 12to6? I hope you can understand what I’m trying to ask. Thanks Mark

How to Sharpen Your Lawn Mower Blades in Under an Hour

Uneven grass, torn blades, and frayed edges, oh my! If your grass looks a little worse for wear, your lawn mower blades might be telling you it’s time for a good sharpening. Luckily, if you have an hour to spare, our guide will show you simple ways to sharpen your lawn mower blades so you can get back to beautifying your yard in no time.

Not experienced handling mower blades? It’s best to hire a pro instead if you don’t have a strong DIY background to ensure your safety.

Why Do I Have to Sharpen My Lawn Mower Blades?

Sharpening your lawn mower blades provides many benefits. Not only will your lawn be healthy and free of diseases, but you’ll keep your lawn mower in good working condition for many years to come. We recommend sharpening your lawn mower blades twice per season or after 25 hours of use.

How Much Does It Cost to Sharpen Lawn Mower Blades?

For DIY-savvy homeowners, the cost to sharpen your blades runs 20 to 60. It all depends on the type of mower you own—reel mowers require less tending, whereas gas and electric mowers require more prep and tools for blade sharpening.

If you don’t have the tools or experience handling sharp blades and working with a lawn mower, hiring a lawn mower repair pro is a great choice. A professional will ensure the job gets done without issue, and you’ll also have the option of adding additional tune-up repairs. You can expect to pay between 25 to 100 for a professional blade cleaning and tune-up.

It costs between 10 and 250 for a lawn mower tune-up

Signs You Need to Sharpen Your Lawn Mower Blades

If your lawn mower blades are dull, these are the telltale signs you need to give them a sharpening:

  • Torn, ragged, and uneven grass
  • Blades of grass are brown, especially at the tips
  • Lawn disease—fungus, patches, mildew, blighting, spots, or mold
  • You’ve hit rocks, sticks, or debris when mowing

How to Prep for Sharpening Your Lawn Mower Blades

Safety disclaimer: Working with any kind of blade poses a danger. If you don’t take the proper precautions, you could injure yourself. Wear safety goggles, gloves, pants, and a long-sleeved shirt to shield yourself from metal shavings and sparks. If you aren’t certain of your ability to handle this DIY project, contact a local lawn care service.

Don’t skip any steps when it comes to prep—your safety depends on it.

  • Turn your mower on its side (making sure the air filter and carburetor are lying face up) and prop it up with cement blocks.
  • Place a two-by-four piece of lumber between the blade and the lawn mower to keep the blade still.
  • Grab a clamp to hold the wood in place. Take a moment to mark the bottom of the blade with a marker, so when you put it back on, you’ll know which side faces up (this is a huge time saver).
  • Loosen the blade by locating the nut attached to the drive shaft. Turn the nut counterclockwise with a wrench until the blade comes off.

If your blades are rusted or full of debris, you’ll want to spray them with penetrating oil and scrub them clean with a brush or cloth before starting your blade sharpening project.

How to Sharpen Your Lawn Mower Blades

The most common lawn mowers are gas and electric models. You’ll simply need to remove the battery for an electric mower before you begin sharpening.

However, if you have a gas-powered motor, you’ll need to grab your safety glasses and gloves and disconnect the spark plug wire. Ensure you tape the wire to the outside of the mower with heavy tape so it doesn’t accidentally plug back in and turn on. Finally, you’ll need to drain the gas tank to prevent any fuel spills.

If you have the proper knowledge and experience, this DIY should take you under an hour. There are three blade-sharpening options to choose from below, but the final step applies to all.

Sharpen With a File

Put on your gloves and safety glasses. Place the blade into a vise with the sharpening edge facing upwards.

  • Grab a 10-inch metal file and stroke the blade in one direction only at a downward 45-degree angle.
  • Apply pressure and continue stroking until your edge is as sharp as a butter knife (this can take up to 50 strokes).
  • Turn your blade over and repeat on the other side.

Use a Blade Sharpening Kit

A blade sharpening stone fits on any standard electric drill, and you can purchase a kit (for around 15) at any local hardware store. The kit includes a 2-inch aluminum oxide angled wheel that sharpens your blades in minutes.

  • Put on your gloves, safety glasses, pants, and a long-sleeved shirt.
  • Place your blade in a vise.
  • Insert the blade sharpening stone into the drill and tighten.
  • Line up the stone with the blade—placing the flat part on the back edge and the curved part on the curved edge of the blade.
  • Run the stone over the blade (back and forth) for a few minutes until the blade is as sharp as a butter knife.
  • Turn the blade over and repeat on the other side.

Sharpen With an Angle Grinder

Angle grinders cut through tile and are tough enough to remove grout and polish metal. They also provide a quick way to sharpen your mower blades.

You’ll see sparks fly for this option, so you’ll need gloves, protective eyewear, a long-sleeved shirt, pants, and ear protection.

  • Place your blade in a vise.
  • Choose a flap disc attachment (grind, blend, and finish all in one).
  • Place the grinder along the cutting edge of the blade.
  • Run the grinder along the edge, moving back and forth.
  • Sharpen until the blade is as sharp as a butter knife.
  • Turn the blade over and repeat on the other side.

After sharpening your blades, they can become unbalanced—which could damage your mower. We recommend purchasing a blade sharpening and balancing kit to perform a balance test. These kits are universal. You can find them at your local hardware store for around 12. If your blade is off balance, simply file it down until balance is achieved.

Place Your Blades Back Into the Mower

  • Clean the bottom of your mower with a brush, and scrape off any clumps of grass.
  • Reattach your blades, ensuring that the side you marked is face up.
  • Wedge your two-by-four under the blade and clamp it. Tighten the nut with a wrench.
  • Reconnect the spark plug, fill the tank with gas (or insert an electric charger), and you’re all set!

The average cost for a new lawn mower is between 80 and 3,200, depending on its type and special features

How to Maintain Your Lawn Mower Blades

To keep your mower and blades in good condition, you should maintain a routine lawn mower maintenance schedule.

Track how long it takes to mow your lawn and keep a record. When you hit 20 to 25 hours, it’s time for a blade sharpening. Also, if your blades have cracks or dents, replacing them is a good idea instead of trying to sharpen them.

Additional Questions

What’s the best way to sharpen a lawn mower blade?

The quickest way to sharpen a blade is with an angle grinder. However, a blade sharpening stone is less hazardous and does a great, fast job at sharpening your blades.

What type of file do I use to sharpen my mower blades?

You’ll want to use a 10-inch mill bastard file for sharpening your blades. These files are great for sharpening saws, chainsaw teeth, and knives. You can purchase them at any hardware store for around 7 each.

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