How Do You Sharpen Lawn Mower Blades? (The Best Way)

For your lawn mower to be effective at its job, you need to have its blades sharpened at least once a year. Both use and disuse of the blades makes them blunt and the solution is simply sharpening them.

After tuning up your lawn mower, the next thing you’ll want to do is to sharpen your lawn mower’s blades. Having sharper blades for your lawn mower makes it easy to keep your lawn neat and free of pests and diseases.

When it comes to sharpening the blades, you have several options on your hands including whether you’ll remove them before sharpening or sharpening them while they’re still on the mower. You also have a choice to make in terms of the tool to use with the options being files, whetstones, grinders and others.

How to Sharpen Lawn Mower Blades (Without Removing)

Tools Needed

  • Grinder or file
  • Goggles or safety glasses
  • Safety gloves
  • Wire brush and steel wool
  • Block of wood about 12” to 18” long

1. Prepare for the sharpening

As with everything done right, preparations come first. For this step, gather the items listed above. Make sure the file or grinder you’re working with is in good condition for the best sharpening experience. A rusty one won’t do you much good.

Make sure the lawn mower can’t turn itself on and slice off your fingers and hands. Turn off the mower then disconnect any sources of power on the mower. Most importantly, ensure the spark plug is disconnected and removed from the mower in totality.

Since you will be tipping up your lawn mower to easily access the blades below the mowing deck, we recommend draining gas from your lawn mower or adding a plastic sheet on the fuel cap so that the gasoline does not spill from the tank.

2. Put the lawn mower on its side

With the blades located below the mower, you’ll need to place it on its side with the carburetor on the top side. For stability purposes, you need to place the block of wood below the mower. This will stop the mower from moving around when you’re sharpening the blades.

3. Secure the blade

First, secure the blade to avoid injuring yourself. This should be done by putting a wedge over the cutting edge and below the blade. You can do this with pieces of wood. After securing the blades, try pushing on them to check whether they move about or not.

4. Wash the blades

The blade picks up debris such as grass, soil and others and can’t be sharpened in this state. You should carefully wash it with clean water until all the debris is removed before attempting to sharpen it up.

5. Sharpen the blades

The sharpening process is the same whether the blades are on the mower or not. However, you need to add a few important steps both to increase the effectiveness of the process and to make it safer for yourself.

The level of difficulty changes with the sharpening tool you have on hand. A file is the best option when then blades are still on the mower. You can also use a grinder although with some meticulous input on your end.

Some tips to put in practice when sharpening your mower’s blades include the following:

  • Sharpen it with uniform strokes away from the center of the blade.
  • No matter the tool you’re using, use a specific angle and maintain it throughout the sharpening process.
  • Always sharpen forwards and never draw backwards.
  • Sharpen one edge at a time.
  • Empty the fuel tank before starting the sharpening process. It keeps you safe and doesn’t lose your fuel.
  • Check to know whether sharpening the blades will improve them or you need a new set of blades. If the blades are damaged beyond some extent, get new ones.
  • Check the grass blades to determine whether the blades of your mower are sharp or not. If the grass blades are clean-cut, the blades are sharp. If not, you need to sharpen them.
  • When sharpening nicked blades, make sure you smooth out the nicks for the blade to have a continuous finish for better mowing.
  • Balance the blades correctly each time you sharpen them. They can be hit out of correct alignment with parts such as the driveshaft hole and the blade itself causing the misalignment.

With these tips, you will not only have a sharp mower, but it’ll also serve you for longer.

After sharpening the blades, you can set up your mower and head out to your lawn again. If you did it right, you’ll notice that you spend less time over each spot on the lawn.

How to sharpen disconnected mower blades

If you’re removing blades from the mower before sharpening them, the procedure is as follows:

  1. Disconnect the source of power from the mower to eliminate any chance of the mower turning on. For a gasoline one, unplug the spark plug and, for an electric one, remove the battery.
  2. Turn the mower on its side to expose the retaining bolt or nut which secures the mower’s blade.
  3. Lock the blade in place with a piece of wood then use a wrench to undo the bolt. Remove the blade while marking the side of the blade that goes into the underside of the mower.
  4. Clamp the blade in a vice such that the cutting edges of the blade face upwards for ease of access.
  5. Use a grinder or other sharpening tool to sharpen the blade accordingly.
  6. Balance the blade to make sure it’s in the correct proportions on either side of the retaining bolt. You then finish off this process by refitting the blade unto the mower.

How sharp should a lawn mower blade be?

There’s a thin line between your mower’s blade being too sharp and just sharp enough. To put it plainly, your mower’s blade ought to be aggressively sharp but not sharp as a razor. You should gently run your finger on the sharp edge of the blade without cutting off your hand. In fact, if it’s too sharp, it won’t cut grass for long.

Final Thought

A lawn mower with sharp blades not only make the grass cutting task effortless but also conserve fuel. Blade sharpening is a key maintenance practice that should be conducted every season.

Leave a Comment