How To Sharpen Lawn Mower Blades

Are the cutting blades of your lawnmower blunt and not sharp anymore? Then it’s time to sharpen them. Heres a how to sharpen the lawn mower blades guide.
Dull and blunt lawnmower blades rip and tear the grass, leaving a ragged cut, which not only looks bad but also allows more chance of diseases affecting the lawn.

grass cut with dull mower blades

Before any work on the lawnmower blades, remove the spark plug wire and make sure the controls are in the off position, after all, it is the grass you want cutting not your fingers. Some self-start lawnmowers have a built-in wind-up spring.
Make sure the spring is discharged before working on the lawnmower. To discharge the windup spring, remove the sparkplug wire and attempt to start the mower. This will run down the spring and make it safe to work on the lawnmower. Turn the lawn mower on its side, just enough to get at the bolts holding the cutting blade in place. Do not turn the lawnmower right over as this allows the oil in the crankcase to slip past the piston into the combustion chamber.
Keep the fuel tank lid in the higher position so fuel will not spill out when you tilt the lawnmower at an angle to get at the cutting blade.

Always cut lawns with sharp lawnmower blades

Take a good look at the way the blade is held in place, before removing. There may be two or three pieces involved and you need to remember how to reassemble.
Next Mark each piece with a marker pen.
Remove the bolt, or bolts and the cutting blade. Scrape out all the dirt and grass accumulated under the metal deck. A big screwdriver or sharp stick works well for doing this.
Take the cutting blade and sharpen it with a file or electric grinder Sharpen to 25
degrees, not razor sharp, but leave a 1/64 tip. A razor sharp edge will curl and dull very quickly. Follow the original pattern, of the blade, you only need to sharpen the tips, approximately one to two inches from the ends. Sharpen both ends the same amount, this keeps the blade in balance.
Take the blade, place the center of the blade on a small finishing nail driven into the end of a workbench. Place one drop of oil on the nail in the center of the blade,
if it does not remain horizontal, file or grind a little more off the heavy side. Normally a quick touch sharpening does not change the balance.

Check Cutting Blade For Cracks

Place the shaft of a screwdriver through the hole in the center of the blade, and give the blade a hit with a metal hammer, the blade should ring like a bell. A cracked one will not.
Reassemble the blade to the lawnmower engine, using the marker pen lines you placed earlier as a guide to reassemble. Tighten the nut securely.
If you are in doubt which way the blade goes, keep in mind that the sharpened tip will be the lowest point and will be positioned so as the arm rotates the grass will be thrown upward. Re-check tightness again after first use.

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