How Do I Sharpen or Replace the Blade on a Lawn Mower?

by Mike Palmer

Grass Cuts Caused by Dull Lawn Mower Blades

Leaf blade A is what your grass should look like after cutting.

The picture above shows how leaf blades look when cut by a sharp vs. a dull lawn mower blade. Leaf blade A shows the cut a sharp mower blade would make while Leaf blades B, C, and D show cuts made by mower blades with various degrees of dullness.

Why Should I Keep My Lawn Mower Blade Sharp?

When your mower blade is dull, it will take longer to mow the yard because you have to make more than one pass to get all the grass cut. A sharp blade cuts leaf blades clean with less effort and enables the grass plant to recover more quickly. Keeping the blade sharp will prevent those brownish spots caused by mowing. This is one of the keys to a healthy lawn that’s green and lush.

How Often Should I Change or Sharpen My Lawn Mower Blade?

Lawn Mower Blade Clamp

Once or twice a year should be enough, unless you’re doing some heavy-duty mowing.

Tools You’ll Need to Sharpen or Replace a Lawn Mower Blade:

Lawn Mower Blade Clamp

Socket Wrench

Lawn Mower Replacement Blade, or

Lawn Mower Blade Sharpener & Balancer

Step-by-Step Instructions on How to Sharpen or Remove the Blade on Your Lawn Mower

Step 1: Remove the spark plug wire from the spark plug. This will prevent the lawn mower from accidentally starting.

Step 2: Before tipping the mower on its side, make sure the cap on the gas tank is tight to avoid gasoline spillage. For additional assurance, you may want to put a piece of heavy-duty plastic over the mouth of the gas tank before tightening the cap.

Step 3: Place a lawn mower blade clamp over the blade to secure it.

Step 4: Use a socket wrench to remove the blade.

Step 5: Once the mower blade is removed, this would be a good time to scrape off the caked-on old grass clippings. It is always a good idea to keep the undercarriage of your lawn mower clean.

Step 6: If you are replacing the lawn mower blade, install the new blade on the mower. Be sure the correct side is up or the blade won’t cut!

Step 7: If you want to sharpen the blade, use a lawn mower blade sharpener and follow the instructions provided.

Sharpening or replacing your lawn mower blade should be made a part of the regular maintenance of your lawn mower (along with regular oil change for your mower). By following a few simple steps, you can have a sharp-looking lawn (pun intended) that’ll be the envy of the neighborhood.

See also: The complete lawn mower tune-up checklist.

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