Do Brand New Lawn Mower Blades Need to be Sharpened?

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

If you’re wondering 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.

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

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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

man sharpening lawnmower blades

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? 

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. 

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 

  • Your mower is working overtime 
  • The grass is not smoothly cut on top but is somewhat chewed 
  • Hitting gravel, stones, and dirt can cause dull blades
  • Grass blades look torn instead of sliced

1. 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.

2. 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:

  • The grass recovers quickly and is less susceptible to disease and pests 
  • You get a beautiful, healthy lawn 
  • Grass tips that are cleanly cut regularly hardly turn yellow or discolor
  • Your grass heals quickly and continues to thrive
man cutting grass with sharpened mower blades

Do I Need to Remove the Lawnmower Blade to Sharpen it?

This depends on how badly damaged or worn the blade is, but I always remove the blade to sharpen it as it tends to be easier this way and doesn’t cause the mower to vibrate.

You can use a wrench or even your hand to loosen the bolt that secures the blade to the mower. My lawnmower features an upright and compact footprint, so it’s easier to access and remove the blade. 

Speaking of which, when tipping your lawnmower to remove the blade, wear safety gear like gloves and eye protection, and refer to your user manual to ensure that you don’t saturate the air filter with oil. 

Pro Tip: Elevate the lawnmower on blocks for easy access to the underside without tipping the lawnmower. 

Here is what it looks like if tilted:

man removing lawnmower blade with beaker bar

Lawn Mower Blade Sharpening Tools 

Sharpening dull mower blades is easier than you think, and there are several ways to go about it. 

  • 10-inch file 
  • Gloves 
  • Eye protection 
  • Vice grips 
  • Bench grinder for a sharp blade
  • Drill and sharpening stone for really worn blades

You can also use one of these blade sharpening tools on Amazon. Alternatively, you can buy new lawn mower replacement blades altogether.

3 Ways to Sharpen Mower and Mulching Blades 

Method 1 – Clamp and File – Easy Tool to Sharpen Lawnmower Blade 

This method is regarded as the easiest way to sharpen a dull lawn mower blade. All you need is a flat file, and a blade secured with a vice.

Grind down any imperfections in the metal by applying pressure on the file until you achieve the shape of the existing edge. Repeat this process for the other side. 

Method 2 – Use a Bench Grinder – Fastest Way to Sharpen a Lawnmower Blade 

If you have a bench grinder in your tool arsenal, you can use it to sharpen a dull blade edge and an entire lawnmower blade. Here are 9 steps for using a bench grinder properly.

Get a good grip on the blade, and grind its edge against the spinning wheel of the bench grinder, and you’ll have a sharp blade within a couple of minutes. 

Method 3 – Use a Drill and Blade Sharpening Stone 

This method is similar to using a bench grinder and is much faster than hand filing. 

Read my detailed article on how to sharpen a lawnmower blade.

How to Balance Mower Blades After Sharpening? 

A lawnmower blade typically becomes unbalanced during the sharpening process, given that you grind more metal from one side than the other. An unbalanced blade rarely affects the quality of your cuts, but can cause wear and tear to the mower. 

You can use a simple blade balancer to test the balance, and then trim the heavier side until the blade is properly balanced. 

Now reinstall the sharpened and balanced blade in your mower, but be sure to secure the blade tight. Follow this guide to change and reinstall your lawnmower blade.

man balancing lawnmower blades

Still curious? Check out this video from “Brian’s Lawn Maintenance” about sharpening brand-new mower blades:

Stop Doing This!! It's Completely Unnecessary! ► Sharpening Lawn Mower Blades FAQ

Final Thoughts

Lawnmower blades fresh out of the box do not need to be sharpened, but over time will turn dull after approximately 25 hours of use. Sharpening a dull lawnmower blade is easy, and you can perform this task with a file, bench grinder, or sharpening stone.

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