Mulching lawn mowers cut the grass and re-cut it until it becomes very small particles, it then shoots those grass particles back into the lawn. Mulching your lawn returns nutrients back into the soil, basically fertilizing the lawn each time it is mowed. Another benefit to a mulching blade is that you will not have to bag your clippings and fill up your trash cans, saving you both time and money.
To continue receiving the benefits of a mulching mower, it is necessary to keep the mulching blade sharp. The blade should be sharpened after every fourth or fifth cutting. If the blade is allowed to dull, the lawn will suffer in appearance and health. Dull blades will not make a clean cut, which exposes the grass to disease and fungus.
You can pay someone $10 a whack to sharpen your lawn mower mulching blade, or you can do-it-yourself in about 10 to 15 minutes. Sharpening your own mulching blade is quite simple, just follow the directions below and you will enjoy a healthy and attractive lawn.
Before you begin, you will need the following items: safety goggles, gloves, block of wood, adjustable wrench, wire brush, bench vise, angle grinder, and steel file set.
Step 1: For gas-powered mowers, make sure the engine is cool and then disconnect the sparkplug. If you have an electric or battery-powered mower, unplug it from the electrical source or disconnect the battery.
Step 2: Turn the mower on its side to access the mulching blade. If gas-powered, tilt the mower so the air filter and carburetor are facing upward, this will prevent gas from leaking.
Step 3: While wearing the safety glasses and gloves, place the block of wood between the mulching blade and the cutting deck (mower underside), the mulching blade ends should point to 6 and 12 o’clock, you may have to use your foot to steady the block.
Step 4: With your adjustable wrench, remove the bolt located in the center of the mulching blade. Typically a 5/8″ wrench will fit the bolt, I recommend an adjustable wrench for the first attempt to limit the time the mower sits on its side.
Step 5: Set the mower back in the upright position until the mower mulching blade is sharpened and ready to be re-installed.
Step 6: While holding the mulching blade, scrub the blade rigorously with a wire brush to remove grass and debris.
Step 7: Secure the mulching blade in the vise to hold it steady for sharpening.
Step 8: Inspect the mulching blade for burrs and pits and remove any jagged edges with the steel files.
Step 9: Using the angle grinder, sharpen the mulching blade using smooth even passes. Be sure to follow the angle of the mulching blade cutting edge, count the number of passes you made on the blade with the grinder, and the amount of pressure you applied. The mulching blade does not have to be razor sharp, slighter sharper than a butter knife is more than acceptable.
Step 10: Reverse the blade in the vise to sharpen the other end, apply the same pressure and number of sharpening passes.
Step 11: When satisfied with your sharpened mower mulching blade, remove it from the vise and check the balance. To check the balance, hang the blade from a nail through the center bolt hole. The ends of the blade should point roughly to 3 and 9 o’clock, if an end drops down, place the blade back in the vise and make a few more sharpening passes on the heavier end, and then recheck balance.
Step 12: Turn the lawn mower back on its side, with the blade’s sharp cutting edges facing down, reattach the mulching blade, and be sure to tighten the bolt with the adjustable wrench.
Step 13: Stand the mower back in the upright position and reconnect the sparkplug.
While it may seem like a lot of work, sharpening you mower mulching blade really is very simple, and it will only take 10 to 15 minutes. Your wallet and your healthy lawn will truly appreciate and reward your efforts.