How to Sharpen & Balance a Lawn Mower Blade

Your lawn mower blade is bound to become dull with long-term use. A dull blade rips through grass roughly, and this can leave behind torn tips making your lawn have a rugged appearance. This will also make the grass more susceptible to pests and diseases.

Sharpening and balancing the blade will ensure that you'll be able to cut the grass quickly, helping you to reduce your mowing time. It also allows you to cut your grass cleanly, allowing your grass to recover and heal quickly, resulting in a healthy lawn. A balanced mower, on the other hand, will keep your mower more durable.

Sharpening a mower blade is easy, and you only require a few basic tools. In addition, you should sharpen the blade of your lawn mower at least once during the cutting season, and two to three times it is exposed to rocks, or if you scalp the ground regularly.

How to sharpen a lawn mower blade

1. Prepare the blades for sharpening

First thing first, ensure that you wear proper protective equipment such as gloves and safety glasses. Also, ensure that your work environment is clean and clear the area of anything flammable. In addition, ensure to follow safety guidelines for all the equipment you'll be using.

Remove the blade

The first step is to remove the blade from the mover, and it involves the following steps;

Step 1

Disconnect the spark plug and the power source (remove the battery if it is a cordless mower) before disabling the mower to prevent the motor from starting accidentally. Tape the spark on the back of the mower so that it doesn’t flop back.

Step 2

Turn the mower onto its side with the carburetor and the air filter side facing up to help prevent the gas and engine oil from spilling. Also, you can pour the oil into a different container to avoid spillage or run the mower until it is out of gas. This will also serve as a good opportunity to check the oil level and change if needed.

Step 3

Remove the blade by wedging a short wood between the deck and the deck to clap the blade. Use a long-handled wrench to loosen the nut/bolt and turn it in an anticlockwise direction to remove the blade. If the nut is stubborn, you can apply some penetrating oil and let it rest for about 10 minutes before you try again.

Step 4

It is essential to note the side of the blade that faces downward as you will need to bolt it back in the same orientation. If you make the mistake of reinstalling the blade upside-down, the blade will not be able to perform, no matter how sharp it may be. You can put a noticeable dot on the bottom or top side of the blade before removing it.

It is important to note that depending on the type of mower, you can still sharpen your blade without removing it. This allows you to save a considerable amount of time. However, taking of the blade off allows better access to the cutting edges as well as enabling you to inspect the blade for any damage.

Inspect the blade carefully

Inspect the condition of the blade thoroughly to determine if it just has some minor dings or if it is completely dull. If your blade is suffering from deep nicks or is noticeably bend, then it may need professional re-grounding, or you may need to replace it altogether. You can also take this time to clean the blade of grass clippings and rust.

2. Sharpen your blade

Your blade typically consists of cutting edge on both ends, positioned on opposite sides, usually four inches or so long. You'll need to clamp the blade in a vice or any other clamp with either of the edges facing upwards and in a way that makes it convenient for you to sharpen the blade. You can use the following methods to sharpen your blade;

i. How to sharpen a lawn mower blade with a file

This involves using a metal file along the cutting edges of your lawn blade. You'll need to run the metal file along the edges while stroking from the inside of the edges until you achieve a clean and shiny look. Flip the other side and repeat the process. It is always a good idea to wear a face mask and a respirator to protect yourself from metal fillings as you sharpen your blades.

While sharpening, keep the file at an angle of the bevel, usually 40 to 45 degrees of any other specified angle depending on the exact manufacturer. Your blade should ideally not be razor-sharp; rather, it should be roughly sharp as an ordinary butter knife.

After you are done sharpening, it is now time to reinstall the blade back to the mower. Apply some lubricant on the bolt to prevent rusting and secure it tightly. Ensure that the blade is mounted correctly with both the upward and downward sides facing in the appropriate direction.

ii. How to sharpen a lawn mower blade with a bench grinder

If you don't want to use a file to sharpen your blade or your blade has some minor cracks and dent, a bench grinder should be the best solution. All you need is to move the blade in a back and forth motion, against the grinder wheel. Just as when using the file, you'll need to maintain the recommended angle as you sharpen the blade.

Alternatively, you also can use a belt sander by applying the same principle of running the blade against the abrasive sandpaper. When using a belt sander, the belt should face up, and the trigger should be in the "on" position.

However, this method of sharpening can cause the blade to overheat due to the intense friction that comes with sharpening. The extreme heat can weaken your edges, and to avoid this, it is vital to cool the blade as it is being sharpened. You can do this by keeping a pan of water by the side to dip the blade as it heats up. However, remember to dry it before you resume sharpening.

3. Balance the Blade

After sharpening your blade, it is crucial to ensure that both ends of the blade are balanced. An unbalanced lawn mower blade can cause excessive wobbling, and this can damage the motor. To check if your blade is well balanced, use a nail to support it from the center and hung the blade on the wall. If it is not well balanced, it will tip to one side. Use a file to make a few light passes on the side that is tipping and try to balance it again.

However, the best technique of balancing a blade is to use a lawnmower balancer. The balancer should be placed on a flat surface with the blade set on top. If your balancing is correct, the blade will remain level. If it is not balanced correctly, it will tilt on one side, thereby indicating which side needs to be filed. This means you'll need to run it through your lawn mower blade sharpener a few times before trying to balance it again. However, you should be careful not to interfere with the cutting edge while filing.

Now that your blade is sharpened and balanced, you can place it back into position. Tighten up the bolt using a wrench. Under-tightening the nut may sometimes times make the mower hard to start. Reattach the spark and ignition wire, and that way, you are ready to put your sharpened mower out for testing.

In conclusion, it is essential to get in the habit of sharpening your blade regularly to ensure that you are always ready to go. Also, keeping an extra sharp blade will come in handy even as you wait to sharpen the dull one later on. Finally, if sharpening and balances seem unsafe or difficult, it is always a good idea to enlist the services of a lawnmower expert.

William Phillips
 

William Phillips was born and raised in Keller, Texas. He is a licensed general contractor, and he has been a home improvement specialist for two decades. His passion for the trade led him to freelance writing to share his life experiences with his readers. Phillips enjoys thoroughly researching DIY tools and writing guides at ToolsHaunt as a way of giving back to the community.

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