How to Sharpen a Lawn Mower Blade

sharpening lawn mower blade grinder

You might think lawn mower blade sharpening requires tons of skill. While years of practice will hone your technique, the basic principles to sharpen a blade are rather simple. Our DIY instructions show you how to sharpen a lawn mower blade quickly so you can save money and keep your lawn looking great.

Why Sharpen a Lawn Mower Blade at All?

You may think a blade spinning at over 180 mph or more wouldn’t need to be terribly sharp to cut grass. You’d be right. However, a nice sharp blade will slice through grass and allow it to grow in a more healthy manner.

Why does this matter? Because “shredded” grass tips will quickly turn brown, leaving your lawn looking ragged and burnt. The following image helps illustrate this:

lawn mower blade sharpening

For professionals, and people who—quite frankly—just like a nice lawn, having sharp lawnmower blades truly matters for a professional look. This goes triple for species like Fescue which grow more or less straight out of the ground and require frequent cutting.

We know professionals who sharpen their zero turn mower blades every other day.

How to Decide Which Way to Sharpen a Lawn Mower Blade

Many ways exist to sharpen a lawnmower blade. Some of the easiest (and quickest) involve using a grinder. The blades don’t actually need to achieve razor sharpness—they just need to have a decisive cutting edge. It’s this edge that slices through, rather than chops, the grass at high speed.

Of course, grinders come in many sizes and forms. Angle grinders, bench grinders…you name it. If you have one of these tools already, then you may have everything you need to sharpen your lawn mower blades. If not, one of our other solutions might work out—so keep reading.

Aside from the use of a grinder, you can also grab a manual file and get to work. Dedicated blade sharpening systems exist that ensure the right angle and consistency when sharpening these heavy blades.

Regardless of which method you choose to sharpen your mower’s blades, we’ll start with the most common and work our way down.

How to Sharpen a Lawn Mower Blade Using an Angle Grinder

Using a small angle grinder to sharpen lawn mower blades lets you accomplish the task with minimal time investment or cost. You can pick up an angle grinder for very little money, and the process involves matching the angle of the existing blade edge and simply honing it.

sharpening lawn mower blade grinder

Steps to sharpen a lawn mower blade with an angle grinder:

  • Remove the lawn mower blade and place it in a vice
  • Attach an abrasive wheel to the angle grinder
  • Run the angle grinder back and forth along the blade, maintaining the existing angle of the blade
  • Balance the blade to assure you removed equal material from both ends (see below)

How to Sharpen a Lawn Mower Blade Using a Bench Grinder

Similar to the process above, using a bench grinder to sharpen lawnmower blades works just as easily. A bench grinder reverses the process. Instead of moving the grinder over the blade—you move the blade across the grinder wheel. Since many bench grinders include an adjustable table, you can often get fantastic and consistent results using this method.

sharpen a lawnmower blade with bench grinder

Try not to over-sharpen the blade. Doing so only results in a too-fragile edge that dulls more easily and weakens the blade. You also want to use quick passes to sharpen the blade. Be careful not to heat the steel too much. If you do, you may inadvertently weaken the hardening process that holds the blade’s edge.

Steps to sharpen a lawn mower blade with a bench grinder:

  • Remove the lawn mower blade
  • Set the angle of the grinder tool rest so that the blade angle matches up to the wheel
  • Turn on the bench grinder
  • Run the blade left and right along the grinder wheel, keeping the blade flat to the tool rest
  • Balance the blade to assure you removed equal material from both ends (see below)

Use a Drill and Sharpening Wheel to Sharpen a Lawn Mower Blade

Another way to sharpen a lawn mower blade involves the use of a cordless drill and a special bit. You can find these in any number of shapes and sizes. These bits match the natural angle of the lawnmower blade.

how to sharpen lawn mower blade drill accessory

Steps to sharpen a lawn mower blade with a drill accessory:

  • Place the lawn mower blade in a vice
  • Insert the bit into the drill
  • Set the drill to High Speed
  • Run the accessory along the sharpened portions of the blade to refresh the edge

One advantage of these types of sharpeners is that you can leave the blade on the mower. Depending on the type of blade and mower, you may get better results by removing the blade first. Still, it does provide a truly quick way to maintain your blade sharpness.

Balancing the Mower Blade

These methods are rather forgiving, however, you should take care to not miss an important step: periodically balancing the blade. After taking off some metal on either side of the blade and achieving a nice edge, you need to ensure the blade still balances evenly.

To do this, hammer a 16D or similar nail into a wall in your shed or shop and hang the blade from its center point. If it stays balanced, you’re all done. if not, mark the heavy side with a Sharpie marker and take some additional metal off that side by continuing to sharpen it. Most of the time, you can keep a blade balanced by staying aware of how many passes you make with a grinder. Still, periodically check the blade balance to ensure you haven’t drifted too far on one side or the other.

balancing lawnmower blade after sharpening

Regardless of which grinder method you use, balance the blade periodically to ensure it stays even.

Other Methods to Sharpen a Lawn Mower Blades

We don’t typically recommend the use of a file when sharpening your lawnmower blades. The process is slow and manual, and the results won’t get you a nicer lawn or a longer blade life. Instead, pick one of the grinder methods above and get to work. If, however, you enjoy using a hand file—by all means, go for it.

If you happen to sharpen mower blades regularly—enough to warrant a faster process—several commercial models do exist to save you time. A newly-created tool from Noracore called the Easy Mower Blade Sharpener (EMBSX) has particular promise. In fact, this tool won a 2019 Pro Tool Innovation Award.

This pneumatic tool drives a die grinder with both a mirror and a camera interface that lets you sharpen the blades on zero-turn mowers without removing them. It takes some finesse and skill to use, so it’s not for everyone. You also need to watch that you don’t sharpen one side more than another or you risk unbalancing the blades.

Noracore Easy Mower Blade Sharpener EMBSX

Some More Considerations

No matter which method you choose to sharpen a lawnmower blade, please be careful to wear proper personal protective equipment (PPE) to protect your eyes, hands, and ears. Grinding mower blades takes little effort and we find it a great entry-level task almost anyone can handle. Still, taking proper safety precautions guards against accidents.

Let us know what you think in the comments below. Do you have a preferred method for sharpening lawnmower blades? Which method works most consistently in your experience? We’d love to hear from you.

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