How to Sharpen Your Lawn Mower Blade: The Easy Way

Approx Reading Time: 9 minutes

While the sharpening of your lawnmower blade may be easily mistaken as a matter of mower care, it is actually a matter of lawn care. Sharpening your lawnmower blade is a very important maintenance task that must be done from time to time. This is because dull blades often tear grass blades instead of cutting them neatly and nicely. A dull blade will rip and pull the grass blades, which often results in ragged tears that weaken the plant and encourage the growth of fungi as well as other grass diseases. As you already know, fungal diseases often take advantage of any open wounds in plants, especially when the weather is moist or humid.

How to sharpen your lawn mower blade, the easy way:

  • Step 1: Disconnet the ignition wire
  • Step 2: Tile the mower and remove the blade
  • Step 3: Note the side of the blade
  • Step 4: Clean the underside of the lawn mower
  • Step 5: Clamp the blade
  • Step 6: Sharpen the blade using one of the following methods: Clamp and File, Using a Bench Grinder Using a Drill and Blade Sharpening Stone
  • Step 7: Balance the blade
  • Step 8: Reattach the blade
How to Sharpen Your Lawn Mower Blade: The Easy Way 1

A sharp blade, on the other hand, cuts your lawn grasses neatly and cleanly, providing a means for the plant to heal and recover quickly. Sharpening  your lawnmower blade also allows you to carry out your lawn-mowing chore faster and easier with less stress on the mower. Sharpening a lawnmower blade is a pretty simple task, and it often takes only a few sharpening to eventually master this technique. Do you want to know how to sharpen your lawnmower blade? You are at the right place. In the rest of this article, we’ll walk you through the best and easy way to sharpen your lawnmower blade.

Why Do I Need to Sharpen My Lawn Mower Blades?

As mentioned above, your lawnmower blade must be sharpened in order to achieve a clean cut. Once the blade gets dull, rather than actually cutting the grass, it will tear the grass blades, and this will cause the grass blade to have a brownish color on the tip. This is not usually a great sight for your lawn as it will appear to be unhealthy when in fact, the lawn could actually be thriving.

What You Need to Know Before Sharpening Your Mower Blade

Before you start the process, there are some things you must know or keep in mind regardless of which tool you choose to use. You need to know how sharp the blade should be when sharpening is not enough, and how often you must sharpen your blade. Since you are carrying out this task to correct the dullness of your blade, it is normal to think that your aim is the sharpest blade possible. However, this isn’t always the case as a delicate balance is what you should be working towards. Undoubtedly, the cutting edge of the blade must be sharp, but it should not be razor-sharp. A razor-sharp edge will not hold out for long, meaning that you will have to sharpen it again, soon. In addition, once you notice large nicks or bends on your blade, you should consider buying a new lawnmower blade. This is because no amount of sharpening can correct the problem. Finally, your blade should be sharpened once every month.

Methods of Sharpening the Blade

When sharpening your lawnmower blade, the idea is to make the blade as sharp as a butter knife, and not razor-blade sharp. This is to ensure its effectiveness since the blade rotates at a high speed. Here are the methods by which you can sharpen your mower blades:

● Method 1: Clamp and File

In this method, you’ll make use of a file to sharpen your dull blade but first, make sure the blade secured in a vice. Apply pressure to the file, then run it perpendicular to the edge of the blade, grinding down any imperfections in the blade and maintaining the shape of the existing edge. After sharpening one side, reposition the blade in the vice and work on the other side. Although this method is slower than when you use a hand file, you’ll still get your results.

● Method 2: Using a Bench Grinder

The fastest way to sharpen a lawnmower blade is by using a bench grinder. Simply grind the edge of your blade against the spinning wheel of the grinder. However, you should always wear protective equipment such as safety goggles, earplugs, and work gloves to avoid the risk of injury. While a bench grinder is usually loud and produces sparks, you’ll be able to sharpen the blade in a matter of minutes. A bench grinder is also a great option for repairing heavily-damaged blades that are hard to file smoothly by hand.

● Method 3: Using a Drill and Blade Sharpening Stone

A blade sharpening drill operates in a similar manner as a bench grinder, but it is much smaller and more affordable. Being faster than hand filing, the stone of the bit is designed to hug the edge of a lawnmower blade, making it easy to sharpen with only little effort. If you’re using a drill attachment, here are some tools and supplies you will need for the job:

  • A power drill
  • Blade balancer
  • Sharpening attachment
  • Workbench
  • Vice and wrench
  • Safety equipment

How to Sharpen Your Lawn Mower Blade

Sharpening your lawnmower blade will take about fifteen minutes (per blade), and the equipment required are a wrench, a vice, a 24” piece of 2×4 or 3” diameter pipe, and a file.

● Step 1: Disconnet the ignition wire

The first thing to do is to disconnect the ignition wire from the spark plug. If you’re using a cordless mower, remove the battery pack. This is to prevent the risk of the engine accidentally starting up while you’re working. You should also drain the gas tank so it won’t spill any fuel while you’re working on the blades.

● Step 2: Tile the mower and remove the blade

Tilt the mower on its side to expose the nut or bolt that secures the blade to the mower. Wedge a short wood block between the end of the blade and inside surface of the mowing deck to keep the blade from turning. Then use a wrench and socket to loosen the nut or bolt. To increase the leverage when loosening any stubborn fastener, you can slip a metal pipe over the wrench handle.

● Step 3: Note the side of the blade

Remember to make a mental note of which side of the blade faces downward. It’s important to bolt back the blade in the same orientation.

● Step 4: Clean the underside of the lawn mower

Once the blade is removed, try to scrape clean the underside of the mowing deck to remove all caked-on debris and grass. You can use a narrow-blade putty knife to get better results. In addition, clean both sides of the lawnmower blade by first spraying it with penetrating oil, and then scrubbing it with a stiff-bristle brush.

● Step 5: Clamp the blade

Next, clamp the mower blade in a vice with one of its cutting edges facing up.

● Step 6: Sharpen the blade

You’ll be making use of a drill-powered blade sharpener. This equipment consists of a round abrasive stone, a flat sharpening guide, and a ¼-inch-diameter steel shank. Chuck the sharpening stone into a drill but remember to first put on your safety goggles. Next, press the trigger to cause the drill to run at a full speed, then put the spinning sharpener over the edge of the blade. When doing this, make sure the dull cutting edge is facing the beveled side of the stone, while the flat surface of the guide is against the rear of the blade. Apply moderate pressure and slowly move the stone back and forth along the cutting edge.

After about five back and forth strokes, pause to check the sharpness of the blade. If it’s not sharp enough, repeat the process until all nicks and chips have been ground off. After sharpening one edge, remove the blade from the vice and rotate it to sharpen the other cutting edge.

● Step 7: Balance the blade

There’s another important thing to note: balancing the blade. Sharpening can remove more metal from one side of the blade than the other, and this may result in an unbalanced blade. Mowing with an unbalanced blade will cause excessive wobbling, which can put undue stress on your mower and damage the motor. There’s good news to this though; you can easily determine if your lawnmower blade is properly balanced or not. Simply slip the center hole of the blade over a nail attached to a wall.

Then hold the blade in the horizontal position and let it go. If either end of the blade rotates down toward vertical, then the blade is unbalanced and the heavier end will require additional sharpening until it’s balanced. However, if the blade remains level, then it’s balanced. The nail-in-the-wall technique may not always provide precise results, hence, you can use a lawnmower blade balancer, or a multi-tiered, cone-shaped metal fixture. Simply place the balancer on a flat surface, and set the blade on top. If it remains level, then the blade is balanced. If not, it’ll tilt to one side, indicating which end is heavier and needs additional sharpening.

● Step 8: Reattach the blade

Once your blade has been sharpened and balanced, attach it back onto the mower, using the wrench to tighten up the retaining nut or bolt. Reattach the ignition wire, replace the battery or fill the gas tank and test run your newly sharpened mower blade.