How to Sharpen a Lawn Mower Blade

Blades become dull with overuse, and a lawn mower’s blade is no exception. A dull mower blade will result in a rougher cut and a less efficient overall machine. Of course, sharpening a lawn mower’s blade is a bit more complex that sharpening a set of kitchen knives. This guide from Holder & Sons Equipment will walk you through the steps necessary to sharpen your lean mower’s blade correctly.

Safely Remove the Blade

First, you need to make absolutely sure that your lawn mower’s engine won’t accidentally start while you are trying to remove the blade. The easiest way to do this is to remove the spark plug. Another helpful tip is to mark the bottom of your mower’s blade with paint or a bit of tap before you remove it so that you’ll have an easier time putting it back once it’s been sharpened. Tilt the mower on its side so that the carburetor is facing up and stick a 2x4 between the deck skirt and the lawn mower’s blade. If done correctly, the blade should resist the board when you remove the bolt. A breaker bar or long-handled wrench can be used to unscrew the bolt. Finally, carefully remove the blade itself.

Inspect the Condition of the Blade

We highly recommend that you have a spare lawn mower blade on hand for this step. By referencing the spare blade, you’ll be able to determine the overall condition of your current lawn mower blade. If you decide that the current blade is too worn out, you can simply swap in the new blade instead of having to order a replacement. Look at your current lawn mower blade to make sure that the cutting edge is straight and the trailing edge is thick. If your lawn mower blade has any dents or chipping, it’s time to replace it.

Sharpen the Blade

Your sharpening file should be at least ten inches thick. Start at the top of the cutting edge and push downward in one firm, smooth, and complete stroke. Do this between twenty and thirty times before comparing your current blade to your spare blade, and decide whether further sharpening is required.

Balance the Lawn Mower Blade

Before you put your lawn mower blade back on your mower, you’ll need to balance it. Our recommendation is to put a nail through a board and set the blade’s bolt hold on the nail. If the blade tips to one side or the other, file that side down. This can be a long process, so be patient and only file a little bit at a time.

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