A Safe Guide on How to Sharpen Lawn Mower Blades

how to sharpen lawn mower blades

Last Updated on May 5, 2021

The blade of a lawnmower might get blunt after a certain period. While a blunt blade might still cut grass in a garden, it is not effective in cutting grass like a sharp blade. Blunt mower blades might make irregular cuts on your lawn.

Such blades can also roughly cut your turf, exposing healthy grass to pests and diseases. Sharpening lawn mower blade is a simple task that helps you restore your blade to its original state. In this post, we will show you how to sharpen lawn mower blades using different tools. Let’s get right into it.

When Should You Sharpen Your Lawn Mower Blade?

Wondering what the perfect time to sharpen a lawn mower blade with different tools is?

Well, mower blades may become dull/blunt after cutting grass in a lawn for a long time. Inspect your blade regularly to check whether it is sharp or not. If you notice any dents on your mower blades, you should sharpen the mower blades for maximum efficiency.

Apart from that, check the performance of the lawnmower as you are cutting grass in a garden. If the lawnmower makes uneven cuts on your turf/grass, the blade might be dull. Also, if the lawnmower is tearing and ripping grass instead of making smooth cuts, the blade might be blunt.

Since sharpening the blade of a lawnmower is a maintenance procedure, you should always sharpen the blade at the start of every mowing season if you want to get a healthy lawn. If you had stored it for a long time (during the winter season), you have to sharpen it before you use it again.

Moreover, the blade of a lawnmower should be sharpened after 25 hours of intensive use. A sharp blade makes smooth and quality cuts on your lawn.

Guidance to Sharpening Lawn Mower Blades

Sharpening your lawn mower blades can be a tricky process, and you can do more damage than good if you don’t know what you’re doing. So let us learn how to do it properly.

Remove the Blade

Start by wearing a pair of gloves.

Sharpening a blade while it’s in a lawnmower can be quite hectic. To avoid this, you have to remove the blade from the interior compartment of your lawnmower. Removing the mower blades from the mower makes it easier for you to inspect the damage on the blade; fractures, stress, and tear. If the blade can’t be sharpened, you have to replace it with a new one.

Before you start this procedure, unplug the power cord from the power source. If you are using a gas lawn mower, turn off the engine and remove the spark plug wire. The engine can’t start if the spark plug cable is disconnected from the mower. It is a safety precaution that prevents an accident.

After that, pour all the fuel that might be in the fuel tank. You can pour it into a container and save it for later use. On the contrary, if you are using a cordless lawnmower, remove the battery from the lawnmower.

Tilt the lawn mower and lay it on its side. The carburettor and the air filter should be facing up. Use a permanent marker to mark the underside of the blade so that you can fix it perfectly on your lawn mower after you sharpen it. You can also spray the bottom of the blades using spray paint.

Afterwards, locate the nut which secures the blade. You can use a metal or a piece of wood to secure the blade to one position and minimize any movements. Place the piece of wood or metal in between the interior part of the deck and the blade. Loosen the nut or bolt with a wrench and a ratchet. Remove the blade from the deck of the lawn mower.

Once you remove the blade from the mower, clean the base of the mower. Get rid of all the mud and debris that might have been stuck on the underside of the mower.

Use a soft piece of clothing to clean all the sides of the blade. If the blade is too dirty, use a soft-bristle brush and some penetration oil to clean it thoroughly.

Blade Sharpening With a File at a Certain Angle

Step 1: Clamp the Blade on a Bench

The first thing to do is by clipping the mower blade to a vice. It minimizes any movements as you are using a file to sharpen it.

Step 2: Sharpen the Blade With the File

Place the file onto the sharpened/chiselled edge of the metal blade. Tilt it at a 45° angle, then slide it on the cutting edge of the mower blade in a downward motion. Do not change the direction of the movement while sharpening the blade. Apply some pressure on the file for effective results. Stroke the mower blade until it starts to shine and becomes sharp. Keep it as sharp as a butter knife. Maintain the same angle (45 degrees) as you are sharpening.

Step 3: Sharpen the Other Side of the Blade

Once you finish sharpening one side of the metal blade, unclamp the mower, then turn it to access the other side. Place the file on the chiselled edge of the mower blade at a 45° angle, and sharpen it just as you had sharpened the other side.

Sharpening the Blade With a Drill

A drill-powered sharpener is a blade sharpening tool that helps you sharpen mower blades in a short time.

Step 1: Secure the Clamp on a Vice

Secure the mower blade on a vice to prevent any movements as you are sharpening the blade.

Connect a blade sharpener to a power drill. Simply put, this is a small and round grinding tool, which features a guiding piece that makes it easier for you to sharpen your blade. Adjust the drill settings.

Step 2: Sharpen the Blades With the Lawn Mower Blade Sharpener

Connect your drill to a power source, then place the round grinder onto the cutting edge of the mower blade. The guide piece should rest on the rear side of the edge, while the grinding stone should rest on the chiselled side of the blade.

Hold the drill sturdy, then press the trigger to activate the rotary motion. Move it along the edge of the blade; start from the end of the blade and apply some light pressure. Stroke it four times to five times until it starts to shine. Maintain the same pressure while sharpening it but be careful not to oversharpen it until it’s razor-sharp.

Check if the blade has been entirely sharpened with the grinder. Release the trigger to stop the rotary motion. Unclamp the blade and turn it to access the other side of the blade. Repeat the same procedure.

Step 3: Check the Balance

Use a blade balancer to check whether the two sides are balanced. If the sides are not balanced, your mower will not function effectively. The rotary motion may produce unnecessary vibrations. Just place your blade on the blade balancer, then check if the two sides are balancing. If one side is heavier than the other, sharpen it a little bit to reduce the weight.

Step 4: Install the Blade on the Mower

Once you finish checking the balance, fix the blade on the mower. Fasten the bolt that you had loosened earlier on.

Sharpen Your Blades

Mower blades can be sharpened by various tools such as a bench grinder, a file, and a drill sharpener. Do not oversharpen the blade. Just sharpen it by applying some light pressure, a little at a time. Make sure that you sharpen both sides evenly. Once you finish sharpening the blade, balance it, then reinstall it back to its original position.

Once you learn how to sharpen lawn mower blades, there will be no excuse for putting off mowing your lawn ever again.

Have you ever tried sharpening lawn mower blades? Do you have any additional tips? Tell us about it below.

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