How to Sharpen Lawn Mower Blades with Grinder


How to Sharpen Lawn Mower Blades with  Grinder

If you want to keep your lawn looking its best, it’s important to have sharp lawn mower blades. Dull blades can damage your lawn, leaving it looking ragged and brown. They can also put extra strain on your lawn mower, reducing its lifespan and increasing the risk of breakdowns. Fortunately, sharpening lawn mower blades is a simple and straightforward task that can be done with a grinder.

In this article, we’ll provide a step-by-step guide to sharpening lawn mower blades with a grinder. We’ll cover everything you need to know, from selecting the right grinder to reinstalling the blades on your mower. By the end of this article, you’ll have all the information you need to sharpen your lawn mower blades like a pro.

How Does a Lawn Mower Blade Work?

A lawn mower blade is an essential part of a lawn mower that cuts the grass evenly to a specific height. The blade is a rotating piece of metal that spins around a central axis, located under the mower deck.

As the blade rotates, the sharp edges of the blade slice through the grass, cutting it evenly. The blade is attached to the motor, which rotates the blade at a high speed, typically between 2000 and 3000 revolutions per minute (RPM).

The blade has a unique design that helps to create a vacuum that lifts the grass, so it can be cut more efficiently. The curved shape of the blade, combined with the speed of rotation, generates a powerful airflow that sucks the grass upwards and holds it against the cutting edge of the blade.

Once the grass is lifted by the blade, it is sliced by the sharp edge, and the cut pieces are then discharged through the side chute of the mower. The height of the grass cut is determined by the height of the blade, which can be adjusted using the height adjustment lever on the mower.

It is essential to keep the lawn mower blade sharp to ensure that it cuts the grass cleanly. A dull blade can tear the grass, which can damage the lawn and make it more susceptible to disease. Sharpening the blade regularly will also help to prolong the life of the mower and ensure that it operates efficiently.

What You Need

Before you get started, you’ll need a few tools and materials. Here’s what you’ll need:

·         Lawn mower blades

·         A bench grinder or angle grinder

·         A dressing stone

·         Safety glasses

·         Work gloves

·         A wrench or socket set


When selecting a grinder, look for one that has a high-speed motor and a grinding wheel that is at least 6 inches in diameter. This will provide the power and surface area you need to sharpen your lawn mower blades quickly and effectively.

Before you start sharpening your blades, make sure you have a safe and comfortable work area. You’ll need a sturdy workbench or table, as well as enough space to move around comfortably.

Removing the Blades

The first step in sharpening lawn mower blades with a grinder is to remove the blades from the mower. To do this, follow these steps:

1. Turn off the lawn mower and disconnect the spark plug to ensure it won’t accidentally start.
2. Lift the mower deck to expose the blades.
3. Use a wrench or socket set to loosen the bolts or nuts that hold the blades in place.
4. Remove the blades carefully and place them on your work bench.

When handling the blades, wear work gloves to protect your hands from cuts and nicks. Inspect the blades for damage or signs of wear, such as cracks or chips. If you notice any damage, it may be time to replace the blades rather than sharpen them.

Preparing the Grinder

Once you’ve removed the blades, it’s time to prepare the grinder for sharpening. Follow these steps:

1. Select the appropriate grinding wheel for your blades. A grinding wheel with a coarse grit of 36 to 60 is ideal for sharpening lawn mower blades.
2. Adjust the grinding wheel so that it is parallel with the blade you are sharpening.
3. Use a dressing stone to clean the grinding wheel. This will help remove any debris or buildup that may have accumulated on the wheel.

Make sure to read the instructions for your specific grinder model before getting started. This will help ensure that you are setting up the grinder correctly for sharpening your lawn mower blades.

Sharpening the Blades

Now that your grinder is set up and your blades are ready, it’s time to start sharpening. Follow these steps:

1. Put on safety glasses to protect your eyes from any sparks or debris.
2. Hold the blade firmly against the grinding wheel at the correct angle. This is usually around 30 degrees.
3. Use light pressure and move the blade back and forth against the grinding wheel until the blade is sharp.
4. Check the blade periodically to make sure it is sharp enough. You can do this by running your finger along the edge of the blade. Be careful not to cut yourself!

It’s important to maintain the correct angle and pressure when sharpening your blades. Too much pressure or the wrong angle can cause damage to the blade or the grinder. Take your time and make sure you are sharpening each blade evenly.

Reinstalling the Blades

Once you’ve sharpened all of your blades, it’s time to reinstall them on the lawn mower. Follow these steps:

1. Make sure the blades are properly balanced and aligned before reinstalling them.
2. Tighten the bolts or nuts that hold the blades in place.
3. Lower the mower deck back into place.
4. Reconnect the spark plug and start the lawn mower to test the blades.

If you notice any vibrations or uneven cutting, you may need to adjust the blade alignment or sharpen them again.

Maintenance Tips

To keep your lawn mower blades sharp, it’s important to maintain them properly. Here are a few tips:

1. Sharpen your blades at least once per season, or more often if you mow frequently or have a large lawn.
2. Clean your blades after each use to prevent rust and buildup.
3. Replace blades that are damaged or worn beyond repair.
4. Store your blades in a dry, protected area when not in use.

Following these tips, you can help extend the lifespan of your lawn mower blades and keep your lawn looking its best.


Sharpening lawn mower blades with a grinder is a simple and effective way to maintain your lawn and keep your mower running smoothly. With the right tools and some basic knowledge, you can easily sharpen your blades at home. Remember to always take safety precautions and follow the manufacturer’s instructions for your specific grinder model.


How often should I sharpen my lawn mower blades?

It’s recommended to sharpen your lawn mower blades at least once per season, or more often if you mow frequently or have a large lawn.

Can I sharpen my lawn mower blades by hand?

While it is possible to sharpen lawn mower blades by hand, it can be difficult to maintain the correct angle and pressure. Using a grinder is a more effective and efficient way to sharpen your blades.

Do I need to balance my lawn mower blades after sharpening them?

Yes, it’s important to make sure your blades are properly balanced before reinstalling them on your lawn mower. Unbalanced blades can cause vibrations and damage to your mower.

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