How to Sharpen or Replace Your Lawnmower Blade | Sward Yard
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How to Sharpen or Replace Your Lawnmower Blade

How to Replace a Lawnmower Blade

Sharp Blades Make For Sharp Looking Grass

Sharpening a lawnmower blade is a crucial step in maintaining a healthy lawn and keeping your lawnmower running efficiently. A dull blade can cause the lawnmower to struggle when cutting grass, leading to uneven cuts and a less than ideal lawn. Dull cuts can also lead to increased susceptibility to disease and insect damage. On the other hand, a sharp blade will make a clean cut, leaving your lawn looking neat and well-groomed. In this article, we'll go over the steps you need to take to sharpen your lawnmower blade.

Inspect your mower blade and see if it needs to be sharpened or replaced altogether. If the blade has too many notches or is significantly bent, it is in the interest of your lawn’s health and possibly your limbs to invest in a new blade. 


Remove The Blade

The first step in sharpening a lawnmower blade is to make sure that your lawnmower is off and the spark plug is disconnected. This will prevent the lawnmower from starting while your are handling the blade. Next, you'll need to remove the blade from the lawnmower. This process can vary depending on the make and model of your lawnmower so it's important to consult the owner's manual for specific instructions. Generally the process follows something like this:

  • Depending on your make and model you may need to tip it on its back or on one side. 
  • Remove the spark plug. 
  • Use a block of wood or something similarly sturdy to prevent the blade from rotating as you torque on the bolts. 
  • Once removed, wipe the blade clean with a dry rag being careful not to cut yourself. 

insect damaged lawn.

Use a block of wood or something similarly sturdy to prevent blade rotation as you loosen the bolts.


Sharpening the Lawnmower Blade

 Once you have the blade removed, clean it thoroughly to remove any grass clippings, dirt, or debris that has accumulated.

With the cleaning complete you can start sharpening. There are several different methods you can use to sharpen a lawnmower blade, including using a file, a grinder, or a bench-top belt sander. They also make adapters you attach to a drill that are pretty cheap and easy to use. If you go the file route, you'll need a flat file and a round file. Start by using the flat file to sharpen the back of the blade, working in a back-and-forth motion. Make sure to maintain the same angle on both sides of the blade. Then, use the round file to sharpen the cutting edge of the blade. This should be done at a slight angle, with the file being pressed down on the blade at the tip. Again make sure the angle is the same on both sides.

You can also use a bench-top belt sander or a grinder, this way it will be easier to maintain a consistent angle.

When using a power tool to sharpen your blade make sure you wear appropriate safety gear such as safety glasses, gloves and ear protection. Metal splinters are no fun.

Once you have finished sharpening the blade, you'll need to balance it. An unbalanced blade will cause vibration and uneven cuts. Blade balancers are available online and at hardware stores for $8-$15 and are often included in blade sharpening kits.

After balancing, make sure to install the blade back onto the mower and secure it properly, following the instructions from the owner manual.


Sharpening your lawnmower blade is an important step in maintaining a healthy lawn and keeping your lawnmower running efficiently. It's a simple process that involves removing the blade, cleaning it, sharpening it, and balancing it. Remember to take proper safety precautions, always consult the owner's manual and use the appropriate tools. With regular sharpening, you'll be able to enjoy a well-groomed lawn with less effort and longer lifespan of your lawn mower.

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washing underside of a lawnmower

Clean and rinse the underside of the mower before you remove the blade.

worn out lawnmower blade

If your blade is too worn, replace it with a new one instead of sharpening the old one.

inspect and change lawnmower air filter

Now is a good time to perform other maintenance tasks like cleaning/replacing the air filter or changing the oil.

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