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How Often Should You Sharpen Lawn Mower Blades? Signs, Tips & FAQ

Lawn Mower Blade

A beautiful lawn is the envy of every homeowner. Most of us spend the weekend attending to our grounds, while others hire professionals to do it for us. But if you enjoy getting your hands dirty and doing it yourself, it can be frustrating when you don’t get that clean straight cut in one go. This can force you to spend precious time chasing after the ever-elusive lawn perfection.

Dull blades are a leading cause of underperforming lawn mowers, and as such, you should always keep track of the hours you have used your blades. On average, a lawn mower blade will require sharpening every 20 to 25 hours of use to maintain its optimal performance. However, the usage hours are not the only indicators your lawn mower blades need sharpening.

This article will examine the crucial information needed to keep your lawn mower blades sharp and cutting efficiently. So if you’re ready to sharpen your knives, keep reading to learn more.

divider 7 How Do I Know When My Lawn Mower Blade Is Dull?

There are a few indicators of a dull lawn mower you can look for both on your lawn:
  • You should be able to cut the grass with one pass to an even height. If your mowing requires several passes to achieve evenness, then it should be clear your blades are dull and need sharpening.
  • If you cut your grass and it turns brown shortly after. The sudden color change indicates that your blade is tearing the grass instead of cutting it because it’s too dull.
  • Visual inspection. Turn the mower over and inspect the blades. Look for bends and dents along the cutting edge and straighten them as you sharpen the blade. The dents are likely to rip the grass rather than slice it clean.
Honda Lawn Mower
Image By: Louiesharpe, Pixabay

Do Brand New Lawn Mower Blades Need Sharpening?

When changing the blades, you might wonder if they need sharpening because they often don’t look that sharp at a glance. However, you will be glad to learn that you don’t need to sharpen a new blade.

Most replacement blades have a powder-coated paint finish making them look thick at the cutting edge and less sharp to the touch. But they leave the manufacturing facility ready to start cutting.

They apply the powder coat paint to the edge for the following reasons:
  • It helps protect the blade’s edges from mechanical damage. The paint shields the angled side when it comes into contact with a hard surface before use or during installation.
  • It makes sure you are protected from injuries, as the paint finish protects you from cuts when installing the blade. Even if you don’t have protective gear, you are less likely to nick your fingers when replacing the blades.
  • To prevent the blade from rusting as a long period usually passes between manufacturing and when you install it for use. Protecting it from moisture is paramount in preserving its integrity, and also, nobody wants to put a rusty part on their shiny mower.

You should also note that the powder-coated paint around the cutting edge starts to disappear after a few minutes or so of mowing.

How Much Will it Cost to Sharpen a Lawn Mower?

The cost of sharpening your blade will depend on whether you are doing it yourself or hiring a professional to do the work. Let’s explore each separately.

Sharpening the Blades Yourself

The only cost of sharpening your blade is the initial cost of buying the right tools. But if you’re like most diligent homeowners, you most probably have them lying around in your garage. However, a simple sharpening tool will set you back $30–$50.

Hiring a Professional

When you hire a trained professional to sharpen your lawn mower’s blades, the cost will depend on the mower type. However, you can expect the payment to range from $20–$60. The price might be less when taking your mower for servicing maintenance, as they will sharpen your blades as part of the service.

Push Lawn Mower
Image Credit: rseigler0, Pixabay

Is it Better to Sharpen or Replace a Mower Blade?

You do not need to replace your blades when they get dull. Blades are made for durability and from rigid materials to help them withstand sharpening and harsh mowing conditions. In addition, regular sharpening will smooth out most of the minor dents and chips. But if you notice a large bend on your blade, it is time to replace it with a new one. Furthermore, it is best to replace the blade when it has 1-inch of the original width eaten up or is overly damaged.

On the other hand, manufacturers will also suggest when to replace your blades and include instructions for sharpening in their manuals.

Can I Sharpen My Lawn Mower Blade Without Removing it?

If you want to sharpen your lawn mower blade, it is safer to do it when it is not attached to the mower. Removing it will help when inspecting for balance. However, if you are in a hurry or unable to separate your blade, follow these steps to sharpen that blade perfectly while attached to your mower.

How to Sharpen My Lawn Mower Blade Without Removing it:
  • Gather the required tools: Cut-resistant gloves, wire brushes, any material you need to brace the mower, and a steel file or angle grinder.
  • Seal the fuel tank: If you use an angle grinder, it would be best to sharpen when your tank is empty.
  • Tilt the mower: Ensure the tank and carburetor are facing in a way that the fuel won’t leak.
  • Brace or support mower: It is essential to set up extra support to work comfortably.
  • Clean the blade with water and a steel brush.
  • Use a file to sharpen the cutting edge gently.
  • Ensure the blade is still securely fastened.
  • Place the mower upright and unseal the fuel tank.

How to Sharpen Lawn Mower Blades

The crucial thing to do before you decide to sharpen the blade is to check whether there are any fractures. The blade’s structural integrity will tell you if it needs replacing, or a simple sharpening will do the trick.

To sharpen your lawn mower blades like a pro, follow these steps:
  • Take time to clean the blade on both sides by scrubbing grass and mud on the surfaces. You can apply a penetrating cleaner and use a stiff bristle brush to remove debris. Leaving any dirt on the blade will make it challenging to get enough abrasion while filing.
  • Clamp the blade firmly in a vice at an angle, and set it in the direction you are sharpening. Make sure to sharpen only the angled side of your lawn mower blade.
  • After sharpening, make sure the blade is balanced. Sharpening removes material from one side and unbalanced installation will damage your motor as it creates undue stress on the lawn mower.
  • Finally, it is time to install your blade. Make sure it is facing the correct way and tighten the bolt firmly.
  • Return the lawn mower to its right side, reattach the ignition wire, and shape that beautiful lawn.

divider 7

Do You Sharpen Both Sides of a Mower Blade?

Lawn mower blades should only be sharpened on one side, never both. Always ensure the file is against the direction of the cutting edge. You will note the file meets resistance in a bite-like manner. That is when you know you are doing it right. If there is no bite, the file is worn out and will need replacing.

man with lawn mower
Image Credit: runzelkorn, Shutterstock

What Kind of Sharpening Tool Should You Use to Sharpen a Lawn Mower Blade?

A file is preferable when choosing a sharpening tool as it is affordable and better than a fast-moving grinder. It is also easier to control and maintain the desired angle for a better finish. The most favorable file length is an all-purpose 10 or 12-inch mill file. It has a good edge and is not overly aggressive to damage your lawn mower blade.

If your blade has several dents from hitting rocks, then a file will not do. Instead, you will need a grinder to smooth those dents and then go back to the file for the angle and an even, shiny finish to the blade.

divider 7 Conclusion

A nice-looking lawn makes it worth your effort to maintain it. A well-sharpened lawn mower blade influences not only your lawn’s evenness but also the grass’s health, evidenced by its color.

A sharp blade is the heartbeat of your lawn, and you should always inspect it before mowing. Furthermore, remember to keep track of the hours you have used the blade and sharpen it every 20 to 25 hours.

Featured Image Credit: Ocskay Mark, Shutterstock


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