How to Sharpen and Care for Your Walk-Behind Mower Blade

A sharp mower blade is instrumental in keeping your lawn lush and well-groomed. These instructions will explain how to properly care for and sharpen the lawn mower blade on your walk-behind. You should periodically inspect the blade adapter for cracks, especially if you strike a foreign object. If you notice dings, nicks or rust on your blade, use a mower blade sharpener to grind a new edge. Replace the mower blade if badly bent or when sharpening is no longer an option. Follow the steps below to safely remove, service and replace your walk-behind lawn mower blade.

Instructions

Step 1 - Prepare you walk-behind mower for maintenance

• Disconnect the spark plug wire from the spark plug to prevent an accidental start or shock. Turn the mower on its side, making sure that the air filter and the carburetor are facing up.

Step 2 - Remove the lawn mower blade

• Start by removing the hex bolt and the blade bell support that holds the blade and blade adapter to the engine crankshaft.
• Take the blade and adapter off the crankshaft. When removing lawn mower blades, always wear work gloves for protection.
  The blade can be sharpened with a mower blade sharpener, a file or on a grinding wheel.
• Do not attempt to sharpen the blade while it is still on the mower.
• Secure the blade in a vice when sharpening with a file or hand-held grinder.
• When sharpening the blade, follow the original angle and grind. To keep the blade balanced, grind each cutting edge equally. You may need to sharpen lawn mower blades once a year to keep them performing well.

• The blade can be sharpened with a mower blade sharpener, a file or on a grinding wheel. Do not attempt to sharpen the blade while it is still on the mower. Secure the blade in a vice when sharpening with a file or hand-held grinder. When sharpening the blade, follow the original angle and grind. To keep the blade balanced, grind each cutting edge equally. You may need to sharpen lawn mower blades once a year to keep them performing well.
   

Step 3 - Service and sharpen the lawn mower blade

Step 4 - Test the mower blade balance

• To test for balance, remove blade and balance it on a round shaft screwdriver.
• Shave metal from the heavy side until it balances evenly. You can also use our Blade Balancer and Sharpener Kit to easily ensure safe, vibration-free operation.

Step 5 - Lubricate the lawn mower's blade adapter and crankshaft

• Lubricate the engine crankshaft and inner surface of the blade adapter with light oil.
• Slide the blade adapter onto the engine crankshaft.

Step 6 - Place the sharpened lawn mower blade back on the mower

• Return the blade adapter such that the side of the blade marked "Bottom" (or with the part number) faces the ground when the mower is in operating position.
• Make sure that the blade is aligned and seated on the blade adapter flanges.
• Place the blade bell support on the blade.
• Align the notches on the blade bell support with the small holes in the blade. Replace and tighten the hex bolt to the torque recommended in your operator's manual.
• To ensure safe operation of your mower, periodically check the blade bolt for correct torque.

Step 7 - Test the balance and starting mowing

• Right the mower and reconnect the spark plug. Check for noises or vibrations when you start the mower and adjust the blade balance if necessary.