Lawn mowers normally use two types of blades. Most commonly, a mower uses a cutting blade. This blade cuts grass and ejects it through a chute out the side of the mower. Also used is a mulching blade. This is designed to cut the grass multiple times and turn the grass into fine particles. These particles fall to earth under the lawn mower and act as a layer of mulch for the grass. Installing a mower mulching blade is something most any home gardener can do using tools available at home or at any home store.
Place the mower on a flat working area. The area should be at least double the size of the mower. Put on the eye protection and gloves. Remove the sparkplug wire from the sparkplug.
Turn the lawn mower on its side. Wedge the 6-by-2-inch wood block between the existing lawn mower blade and the lawn mower housing deck. The wood should be wedged in such a manner that the blade cannot move.
Remove the nut at the center of the existing blade, using a socket wrench. Slide the existing washer from the post. Remove the existing blade from the post. Set aside the wood block. Save the nut and washer.
Place the mulching blade on the post. Reuse the existing washer and slide it on the post. Loosely screw the existing nut in place with the socket and socket wrench. Wedge the wood block between the new mulching blade and the side of the lawn mower deck. Place the socket on the torque wrench. Tighten the nut with the torque wrench to the load required in the lawn mower mulching blade documentation.
Roll the lawn mower back to its cutting position. Place the plug in the lawn mower ejection shoot to keep grass inside the lawn mower housing as it is being mulched.
Reattach the sparkplug wire to the sparkplug. Start the lawn mower. Ensure that the new mulching blade operates without any unusual vibration. Mow a portion of lawn to make sure that grass does not exit from the ejection chute.