How to Sharpen a Mulching Blade

If you own a lawnmower, you know how important it is to do regular maintenance. Among all other parts, blade sharpening is the most essential one.

If you don’t know how to sharpen a mulching blade, this is an excellent place to begin. It is a good idea to sharpen your blade once a year.

Preparation is the key to any successful maintenance session. Every time you are going to do the regular maintenance of a machine, you will need a specific set of tools.

Perhaps you know what I am talking about provided you have done similar work in the past. You will also agree that preparing beforehand cuts down a significant amount of delay.

If all the tools you need are within your hand’s reach, you can do the job more confidently. That’s why we have listed some essential tools to ease your research.

Things You Will Need

  • Safety Gloves.
  • Safety goggles.
  • Oil container.
  • Lifting jacks.
  • Safety Mask.
  • Power drill with sanding attachments.
  • Steel files.
  • Small wood pieces.

Steps on How to Sharpen a Mulching Blade?

Before you start sharpening your lawnmower blade, you need to remove it from the mower safely. Remember, you are working with a grass-cutting machine.

Its dull blades, yet dangerous to some extent. So, you will need caution to proceed.

Lawnmower professionals can do their blade change and sharpen quite early. If it is your first time, don’t worry about the time. You need to do it right instead of doing it quickly.

Step 1: Wear Protective Gears

We cannot emphasize enough the protective gear. It’s safe to say that there are substantial risks in any repair or maintenance work.

Whether it’s a small or big job, the risk impact can be fatal sometimes. So, never skimp out on protective gear.

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We will be working on the lawnmower and its blades. The work requires you to hold the edge often. So it’s logical to wear thick safety gloves.

You will be sharpening the razorblade later with steel files and sanders. There will be a lot of metal particles in the air. That’s why you will also need goggles and a mask.

Step 2: Empty The Fuel Tank

A crucial step in sharpening a mulching blade guide. Every lawn mower runs on fuel reserved in a designated tank.

For repair or maintenance purposes, you will lift the mower or flip one side to access the bottom part. If you do that with a full tank, the oil may leak through the filter or other places.

So it would be a good idea to empty the fuel tank before making any repairs. If you look closely, you will see an emergency release valve around the fuel tank.

Just place an empty container below the valve and release it to empty the tank. After that, store the filled-up oil container for later use.

Step 3: Unplug The Spark Plug

When working with the lawnmower, there is always a risk of accidental ignition or unintended engine startup.

Taking out fuel may prevent this from happening. But there might be some fuel left in the fuel lines which could be enough for an unintentional startup.

Therefore, pulling out the spark plug can be the ultimate stop to that kind of incident. If you are thinking of where to find the plug, carefully look around the engine.

There you will see a wire going into the engine that looks like a plug. Simply pull the plug with decent force. Now you have a complete out-of-action lawnmower.

Step 4: Flip Or Lift The Mower

The lawnmower blade is located under the body. You will need to access the bottom side to remove the edge.

There are two different ways you can do that. If you own a car jack, the work will be easier. Simply place it under the mower and slowly use the lever to lift the machine.

Another way you can do that is to flip the machine sideways. If you emptied the oil tank already, there should be no problem forward. 

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If you can’t do either of those, make a wooden ramp about 10- 15 inches high and place your mower on that. Now you should have enough space to work with.

Step 5: Remove The Blade

If you have completed the above steps correctly, it’s time to remove the blade from the mower.

For that, you will need a wrench and an extension bar to provide the leverage. The issue with the old mower is the nut can get stubborn to unscrew. A wrench extension will come in handy in this regard.

Another issue you may face while removing the blade is the parallel spinning of the nut and the blade.

You either have to grab the blade with safety gloves or stick a wood piece to stop the parallel spinning. Also, you can use a clamp on the blade’s spinning path to unscrew the nut more easily.

Step 6: Sharpen The Blade

You are almost halfway there. You have successfully removed the blade from the mower. Now it’s time to sharpen the blade.

Generally, mower blades are thick and can be sharpened about three to four times, depending on the thickness. If the blade is too thin, you are better off replacing it with a new blade.

The mower blade can be sharpened in many ways, but the most popular methods involve a steel file and a power drill. Using steel files is more of a traditional way.

It is indeed, labor-intensive and needs more time to finish compared to power tools. But they provide a superior finish and maximum control.

Using power tools like a sander or drill machine offers convenience and fast working time. Plus, there are a number of attachments you can use to achieve the desired finish.

Though applying steel files have its perks, you cannot deny the value of a power tool and all the different attachments it comes with.

Now that you know all about the tools, time to sharpen your blade. And, there is a specific way to do that. If you look closely at your blade, you will see there is only one side with a sharp edge.

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The edge is in line with the spinning side. So be careful not to sharpen the wrong edge by mistake.

To get the best result, you need to follow a previous sharp edge grove. Slowly work your way around that to match as much as you can.

Some blades come with a wavy pattern, and some come with curved cutting edges. Be sure to follow those curves for a better sharpening impact.

Step 7: Balance The Blade

Congratulation! By now, you have finished your sharpening and are excited to mow your lawn. But it’s not over yet.

The sharpening process chip off a significant amount of metal from the blade. It means the weight of both sides of the blade probably won’t be the same. In this state, the blade can be very unstable.

You can fix this simply by changing the blade on a nail from the middle. If the blade is leaning down on one side, it means that the side is heavy compared to the other side.

Do some more sharpening on the heavy side to balance the inconsistency. Doing that will subtract the unstable factors from the equation and give you optimal performance.

Step 8: Reattach The Blade

Finally, you have come to the last stage of the guide. In this stage, we will reattach the newly sharpened blade to the mower.

Almost all of the mower blade turns counterclockwise. That means the sharp edge would be on the same counter-clock side.

When reattaching the blade, remember this and screw the nut tightly. If followed the step-by-step guide properly, there should be no problem after this.

Final Verdict

Sharp lawn mower blades keep your lawn clean for all seasons. So, it is crucial that you take care of your lawnmower and yield excellent results.

Lastly, the goal of this blog post was to present all the information on how to sharpen a mulching blade.

Even if you have never done that, we believe reading this article will come in handy in the long run.