A Guide To Sharpening Your Lawn Mower Blade

Your lawn can easily be damaged if you try to mow it with a blade that is dull.  A dull blade will rip the grass out rather than cutting it neatly and also puts extra pressure on the mower's motor, potentially causing damage.  Here's a quick guide on how to sharpen your mower blade.

Safety tips

Before you begin, always turn off the mower and disconnect the spark plug.  This prevents the motor from accidentally firing up and spinning the blade while you're working on it.  The spark plug can just be unscrewed and lifted out.

Removing the blade

Once the mower has been made safe, you can remove the blade.  To do this, tip the mower onto its side so that you can access the blade underneath.

Use a spanner to loosen and remove the nut that holds the blade in place.  If the nut is rusted or stiff, first use some wire wool or a steel brush to remove any rust, and then dress the nut with a few drops of light oil.  Allow the oil to penetrate the nut for half an hour or so, and you should then be able to remove it without resistance.  The blade should now just slide free.

If the mower blade is covered with dried-on grass and debris, use a paint scraper to remove it.  Immerse the blade in a solution of warm water and washing-up liquid until any remaining bits of grass have come away.  Dry the blade thoroughly with an old towel.

Sharpen the mower blade

You can either use a grinding wheel or a manual file to sharpen your mower blade, unless your mower comes with a blade sharpening kit for you to use.  Your aim is to remove any rough spots or pitted areas on the edge of the blade so that it has a smooth edge. 

To get the right angle, just follow the existing edge, using long, smooth strokes until the blade is smooth again.

Tip:  If you don't have a grinder or a file, remove the blade, clean it, and then take it to your local mower shop where they will sharpen it for you.

Balancing the blade

If the mower is to run properly, the blade must be correctly balanced.  To check this, hang the blade on a nail by the screw hole in the centre.  The blade should remain straight.  If it tips to one side, it is not balanced.  You can correct this by removing a little more of the blade's edge with your file, until it hangs straight.

Replacing the blade

Before you replace the blade on the mower, clean the underside of your machine of any old grass or debris, using a stiff brush.

Place a few drops of light oil on the screw that holds the blade in place.  Slide the blade back onto the screw and refasten the nut firmly so that the blade doesn't wobble.

Don't forget to reconnect the spark plug.

In conclusion

You can ensure that your mower performs well this summer by sharpening the blade before you give your lawn its first cut of the season.  For more advice on mower maintenance, have a chat with your local supplier.