How to Put a Blade on a Lawnmower

Lawnmower blades spin somewhere around 3,200 rpm, so using a blade for 30 minutes means it's spun 96,000 times. This means 96,000 chances they'll get dinged, dull and eventually less functional. Replacing the blade on a lawnmower is fairly simple, straightforward process, but there are certain safety tips that must be followed. Along with cleaning the air filter and replacing the spark plug, changing or sharpening the blade on a lawnmower should be part of a regular maintenance program.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Ratchet and socket set Gloves Replacement blade

1. 
    
   This blade needs replacing!

   Turn the lawnmower off. Allow the engine to cool for at least an hour.

2. 
    
   A replacement blade.

   Drain the oil and gasoline from the mower once the engine has cooled. You can accomplish this with a funnel and a gas can, and turning the mower upside down.

3. 
    
   Be very careful when working on lawnmowers.

   Disconnect the spark plug by pulling the connector from the plug, and turn the lawn mower upside down. If you're squeamish, you can remove the spark plug entirely.

4. 
    
   Always wear gloves when dealing with lawnmowers.

   Loosen the blade of the mower using a ratchet and socket, and turning counter clockwise. The blade is mounted on a yoke, usually with one large bolt with a washer underneath. Use a gloved hand to hold the blade steady while using the socket in the other hand.

5. 
    
   You'll need a ratchet set to remove the old blade.

   Put the bolt and washer aside. If you have a replacement blade, attach it by repeating Step 4 in reverse order.

Tips & Warnings

• Replacement blades come in a variety of sizes, so if you're unsure what size you need, bring the old blade into the store with you. Wipe any spilled oil off the engine; otherwise you'll produce a smoke screen the next time you fire up the mower.
• Even dull blades can injure you badly, so wear gloves and long sleeves when replacing a mower blade. Hot engines and spilled gas are a free pass to your local burn unit, so make sure the engine is totally cool before working on a lawnmower.

Resources

• CDC: Lawn Mower Safety
• Snapper