A perfectly manicured lawn starts with a properly maintained lawnmower blade. A sharp blade cuts each blade of grass cleanly, which allows the grass to heal quickly. When grass is cut with a dull blade the grass is torn, leaving a ragged and large wound on each blade. The grass takes longer to heal, which can allow disease into the lawn. The blade on your mower should be inspected at least once a year and sharpened or replaced as needed. Your lawn will actually tell you when your blade needs to be sharpened if you know what to look for. When a lawn is cut with a sharp blade the grass blades will heal quickly and only about 1/32” to 1/16” of the tip will turn brown. When the grass is cut with a dull blade the grass is torn and takes much longer to heal, often causing 1/8” or...
A perfectly manicured lawn starts with a properly maintained lawnmower blade. A sharp blade cuts each blade of grass cleanly, which allows the grass to heal quickly. When grass is cut with a dull blade the grass is torn, leaving a ragged and large wound on each blade. The grass takes longer to heal, which can allow disease into the lawn. The blade on your mower should be inspected at least once a year and sharpened or replaced as needed. Your lawn will actually tell you when your blade needs to be sharpened if you know what to look for. When a lawn is cut with a sharp blade the grass blades will heal quickly and only about 1/32” to 1/16” of the tip will turn brown. When the grass is cut with a dull blade the grass is torn and takes much longer to heal, often causing 1/8” or more of the tip to brown. Performance is another benefit of a sharp blade. A sharp blade requires less power to cut through the grass. This results in better engine efficiency, faster blade speeds, and longer engine life.
Mulching blades require more frequent inspection and maintenance. When mulching, the grass is cut and then the clippings circulate around the mowers deck, being cut over and over until they finally fall from the deck and settle back into the lawn. Much more power is required from the engine as the clippings are sliced over and over. A sharp blade is essential for keeping the engine from bogging down. A dull blade will not cut the clippings as finely as a sharp blade, causing the mower to leave clumps of grass on the lawn.
Another cause of poorly cut grass is a damaged blade. If the blade strikes something solid such as a rock, tree root, or a buried pipe, the blade can be badly bent or even cracked. In addition to cutting the grass poorly, a damaged blade can be dangerous. A bent blade will often vibrate badly, which can cause additional damage to the mower. A bent blade might even strike other parts of the mower. A cracked blade can break at any time, sending the broken piece flying away from the mower.
Replacing your mower blade is a simple repair. Start by tipping the mower so you can access the blade. The mower should be tipped so the carburetor is up, otherwise fuel will spill from the carburetor and onto the ground. Mowers with vented gas caps may need to have the fuel drained out of the fuel tank first or fuel will spill from the cap. This is especially important with newer models that have a charcoal filter in the cap. If fuel gets into the charcoal filter, the cap will no longer vent properly and it will need to be replaced. Once the mower is tipped, the blade can be removed. The blade will be held in place by one or two nuts or bolts, depending on the model. Use a socket wrench to remove these fasteners. Often the blade will rotate when you try to remove the blade with your wrench. If so you can bind a piece of scrap wood between the blade and the mower’s deck so the blade cannot rotate. There will often be washers or a plate between the fasteners and the blade. Take note of the order of any washers or plates so they can be reassembled in the correct order. When installing the new blade, make sure you mount it with the correct side up. The bevels where the blade is sharpened should go up, towards the mower’s deck. Many blades are even stamped “This side towards grass” on the bottom, to help you get the blade mounted correctly. Replace the fasteners and any washers or plates and hand-tighten. Most blade fasteners will need to be torqued to a specific spec. This value can be found in the owner’s manual. A helpful tip is to write the torque value on the mower’s deck so you don’t need to look it up each time you service the blade. Once you have the torque value, use a torque wrench and tighten the blade fasteners. Again, use a scrap of wood if needed to bind the blade while tightening the fasteners. Keeping a sharp blade on your mower will keep your lawn looking great and help to make your mower last for years.
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