Do Lawnmower Blades Come Sharpened?

Lawnmower blades are an essential part of your lawnmower. They are the components that do the actual cutting. They are made with solid metals that allow them to endure high speeds as they come into contact with other materials while working. These blades come in varying designs, materials, sizes, and thicknesses depending on the manufacturer. But no matter what blade you choose, the question that is most likely lingering in your mind is, Do I need to sharpen my new lawnmower blades when I get them, or do they come sharpened?

It’s normal to have these concerns about the condition of the blade to ensure that your mower is set up correctly so you can achieve a clean, healthy cut. You have nothing to worry about when you get new blades because they come already sharpened from the manufacturers. So, you can remove it from its packaging, install it and start mowing.

How Sharp Should Your Lawnmower Blades Be?

If you’re a neat freak, you’re likely very particular about your lawn’s clean-cut. And so, you’ll probably think that to achieve that, your blades have to be extremely sharp. You might even go-ahead to have them extra sharpened to make sure. However, your mower blades don’t need to be razor-sharp to achieve a smooth cut. Since they rotate at high speed, they only need to be butter knife sharp such that you can touch the edges without getting cut.  

Do Lawnmower Blades Come Sharpened?

If your lawnmower blades are too sharp, they can get blunt faster than usual, which can shorten their life span and leave you sharpening them more often than usual. Also, the sharpness angle of the blades should be between 30 to 40 degrees. Not more, not less.

Do Blunt Lawnmower Blades Affect How Grass is Cut?

Yes, blunt lawnmower blades affect how your grass is cut and also the health of the grass. This is because dull blades don’t give the grass a neat cut and so tear the blades of grass, leaving it with a jagged, bruised tip. The effect may cause plants to get weak and make it easy for diseases and fungi to enter the grass. It would also leave the grass with yellow or brown discoloration. 

Well-sharpened blades provide your lawn with many benefits apart from ensuring it looks manicured, green, and healthy. Dull blades pull at the grass blades and tear the edges of the grass instead of slicing through them evenly, leaving them with a lot of damage. Grass that is cut nicely tends to recover from the cut a lot faster, giving the grass a better chance of fighting off diseases. Clean-cut grass can also easily filter out weeds and other unwanted grass. 

Furthermore, cutting your grass with blunt blades puts a lot of strain on the motor of your lawnmower. The grass will wrap around the dull blade shortly before it rips, and the mower would need to have to use a little extra effort to cut the grass. This can cause the mower’s components to get damaged or the mower’s operation life to shorten. Sharp blades allow the mower to work faster and slice through grass easily and with minimal stress to the engine. 

Types of Lawn Mower Blades

Ideally, a lawnmower blade has three primary functions: mulching, bagging, and discharging. Some can perform two or all of these functions, while others can perform only one. And they all have different designs. So, depending on what you’re trying to achieve for your lawn, identifying the different lawnmower blades and selecting the one that best suits your preference will help you get your desired results.  

The different types of lawnmower blades include;

  1.  Lifting Blades:
    1. Low-lift blades: These blades are very suitable for mowing short grasses, generate less noise, and don’t require so much horsepower. The design allows the grass clippings to stay low for easy discharge.  
    2. Medium-lift blades: These blades are very effective on thick grasses and require less horsepower than high lift blades. These blades provide more suction than the low-lift blades.
    3. High-lift blades: These blades are ideal for cutting long, denser grasses. Due to this, the high lift blade requires more horsepower than others. They are best for bagging because they offer a fan-like suction.
  2. Gator blades: The gator blades are thicker than other blades and feature a unique design that helps cut through thick grass. They come with raised teeth that produce a clean-cut, help to improve bagging, and deliver faster decomposition.
  3. Mulching Blades: These blades can bag, discharge, or mulch grass clippings. They come with a curved surface that allows the grass to be kept inside the mower deck and cut before being bagged or discharged. 

How Do You Sharpen Your Lawnmower Blades?

It’s pretty easy to sharpen mower blades yourself. You can use a few handy tools to sharpen your mower blades, including a hand file, angle grinder, or bench grinder. However, a quicker and easier method includes using a drill and sharpening stone specially made to smooth the blades’ edges. Here are a few tools you can use to sharpen your lawnmower blades:

Hand File

This method is one of the most recommended methods of sharpening lawnmower blades. Hand files are very easy to come by as they are used to file metal and plastic and can be found in most workshops. The only downside is that the hand file only cuts in one direction, so the sharpening process can take longer.

lawn mower blade being sharpened with hand file

Angle Grinder

An angle grinder is a quicker solution for sharpening your mower blades than hand files. They are also a very cost-effective tool. To use an angle grinder, you would need to get a clamp that you would use to secure the blade to the workbench. You also need to identify an angle that aligns the grinding disc perfectly with the blade.

Bench Grinder

A bench grinder also provides an easy method for sharpening mower blades. This method is one of the fastest ways to get your sharpening done, as it only takes a few minutes. It’s just as easy as sliding the blade across the grinder wheel till you get the desired sharpness, and it’s perfect for repairing badly damaged blades that a hand file cannot fix.

Drill and Sharpening Stone

This method involves using a sharpening drill and stone to file your blades. It is just as fast as a bench grinder but smaller and more affordable. The stone allows you to sharpen using minimal effort and without error because it holds the edge of your blade firmly in place.  

Despite all these easy methods, you might still not feel confident enough to want to sharpen the blades yourself. So, you can hire a professional. However, if you choose to do the sharpening process yourself, be sure to put on protective gloves, face goggles, a face shield, and clothing that completely covers up your body, such as long-sleeved shirts and trousers. 

Steps to Follow Before You Sharpen Your Lawnmower Blades

There are a few essential steps that you must follow before attempting to sharpen the blades yourself. First, you must disconnect the spark plug wire from the spark plug and disconnect any other power source before you start to prevent any chance of the engine powering up itself while you’re working on the blades. 

Next, you must tip the mower on its side and use a large wrench and socket to unscrew the retaining nuts and bolts in the middle of the blades that secure them. Once you’ve done this, you must mark the lower sides of the blades to prevent putting them back the wrong way. Also, make sure to put on safety gloves when trying to remove the blades.

Once this is done, using a stiff-bristle brush, you must spray penetrating oil and use it to clean both sides of the blades. You can then sharpen the blades till you get even edges. And finally, you must make sure to balance the blades before you reattach them. 


How Often Should I Sharpen My Lawnmower Blades?

Since we’ve established that there’s no need to sharpen your lawnmower blades when you purchase them, you might think there’s no need to sharpen them once you start using them. However, it is imperative to sharpen your lawnmower blades often to prevent having blunt edges that will discolor and tear your grass. Your mower blades should be sharpened about 20-25 hours after use. 

Sharpening your mower blades should be an integral part of your lawn maintenance procedures. Therefore, if it takes you about an hour to mow your lawn every week, you need to sharpen your blades just twice a year. If you hit rocks, you also need to sharpen your blades because stones can easily damage your mower blades. You might also want to watch how well the grass on your lawn is being cut to decipher when your blades are due for sharpening. 

When Should My Lawnmower Blades be Replaced? 

Once your lawnmower stops cutting correctly and you’ve already sharpened the blades, this may signify that your blades are damaged. They could be bent, worn out, or cracked. The crankshaft of your mower could also be bent, or the bushes on your axles could be worn out. However, you might not need to replace your blades only when they’re damaged, and you can have a replacement set handy if you want to use the blades for different purposes. If you choose to have a replacement set, you should replace the blades when you sharpen them. 

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