Having spare lawn mower blades for rotary style power mowers can be very handy, especially if you’re cutting grass in an environment where rocks, gravel and sandy soil are present. Such soil related material is easily picked up by the vacuum action of the mower and it dulls the edges of the blade(s) very quickly. Even common items like twigs can accelerate wear on the edge of sharp blades until they no longer cut the grass, but simply tear into it.
The idea here is to have a spare blade or set of blades ready to go. That allows you to quickly change out dull blades for sharp ones and get back to lawn care. In your spare time, or during the off season, you can resharpen the blade(s) removed from the lawn mower.
Here is how to tell if your blade needs changing:
Grass has yellowing tips from tearing the stalk instead of shearing it off.
It becomes increasingly difficult to cut taller grass clean and quick.
The edge of the blade is starting to round over.
You hit something unexpected in the lawn.
While inspecting blades, use caution to guard against cuts. Also, to make certain there is no chance of placing your hands into operating blades, simply pull the spark plug wire. This effectively kills the engine and prevents it from starting. Leave the spark plug in place as this will reduce the chance that a blade will freely swing around while you’re inspecting it.
When replacing lawn mover blades, make certain to look closely at the blade to be sure it’s not bent from contacting a foreign object in the lawn or yard. Blades (and the shaft it spins on) can bend easily if they contact something that is solid, like a rock or piece of wood. If the blade is bent, be sure to straighten it first and then sharpen it. If the shaft is bent, the mower may still operate satisfactorily, but if not, it will probably require replacement.