Changing a lawnmower blade is sometimes necessary when the quality of the grass cutting diminishes or after striking an object. The blades are located on the underside of the mowing deck that prevents access to the spinning blade. Whether the blade has been bent or damaged or simply needs to be sharpened, changing a lawnmower blade can be an accomplished with the steps outlined here.
Ensure that the lawnmower is not running and has been allowed to cool completely. Let the unit sit for a few hours if it has been running, as lawnmower engines can stay very hot for a long time. Remove the spark plug wire.
Remove any debris from the lawnmower deck area. Brush away any grass clippings, twigs or obstructions from the drive belts and deck top.
Gain access to the blade compartment either by turning the mower over or removing the mowing deck completely depending on the model lawnmower. Be certain all gas has been siphoned from the gas tank before turning unit over. Check the oil cap and ensure it is secure as well.
Place a block of scrap wood between the mowing deck and the tip of the lawnmower blade. This will stop the blade from turning when removing the bolt or nut.
Find a socket that will fit the bolt or nut holding the blade in place and loosen the bolt. Slowly and carefully remove the blade from the spindle.
Slide the new blade over the spindle and return the bolt to the spindle screw. Tighten the bolt or nut to specified torque requirements in the owner's manual of the lawnmower.