How to Use a Bench Grinder to Sharpen Lawn Mower Blades

Mowing your lawn gives you time to yourself. As you push or ride your mower over your yard, you can take time to think, enjoy the fresh air and take a break from the stress of your workweek. But like all chores, mowing your lawn may add to your duties. The lawnmower blade needs sharpening.

How to Use a Bench Grinder to Sharpen Lawn Mower Blades: Fortunately, only a single bolt holds the lawnmower in place. All you have to do is loosen the bolt and then remove the blade. After that, you turn on your bench grinder and wait till it gets to full speed. Just take your time applying the right pressure to sharpen your lawnmower blade.

To get all the tips and pointers, you need to do a good job, just continue to read our article. There is more to sharpening the lawnmower blade than meets the eye.

How to Tell if Your Lawnmower Blade Needs Sharpening


Knowing when to sharpen your blade is important. This will help you protect your lawnmower and keep the blade in top shape. The best way to tell when your blade is dull is to look at a blade of grass.

If the blade has a very smooth edge at the cut line, then your blade is still sharp enough to handle the lawn cutting job. If the cut line on the blade of grass is rough, then the blade on your mower is dull and you need to sharpen it.

Of course, if you hit a rock, cement block or other tough objects, you should sharpen the blade as quickly as possible. Nicks can weaken the blade over time and may cause the blade to break if you hit a rock again.

Keeping the blade sharp keeps it strong and keeps you safer.

Why Sharpen Your Lawn Mower Blade?

There are some very good reasons to keep the blades on your lawn mower nice and sharp. Here are 4 legitimate reasons to take the time to sharpen those blades:

  • The grass is greener - a sharp blade provides an even cut, keeping your grass healthier and less vulnerable to disease.
  • You use less gas or electricity - a dull blade works harder and does not cut the grass. It tears it. This makes the lawn mower work harder and uses more fuel.
  • You use less energy - sharp blades mean you can roll along much smoother and do less work in getting your lawn where you want it to be.
  • The mower is easier to use - why waste time using a mower with a dull blade when you can save time by using one that cuts quicker, easier and more efficiently.

Using a Bench Grinder to Sharpen Lawn Mower Blade


Of course, it is a lot easier to put the lawn mower blade into a vise and hand file it sharp. All you are losing is a little time. But if you do not have the time to sharpen the blade the old fashioned way, a good alternative is to use your bench grinder.

Your bench grinder has the right grit on its wheels to sharpen your lawn mower blade just right. Plus, you can use the second wheel with a finer grit to smooth out any nicks or other abrasions that are on the blade.

Because of the high powered motor, you will have to be careful of the amount of pressure you place on the spinning grinding wheels. You will also have to keep an eye on the angle you are using. You need to maintain that angle to make sure you get the blade as sharp as possible.

Then you will need a steady hand and a lot of patience as one false move may damage the blade and you may need to replace it or work harder to get it sharp. Being careful and safe makes the bench grinder the perfect tool to sharpen your lawnmower blades.

How to Sharpen Lawn Mower Blades With a Bench Grinder

If you follow the following steps, you should be able to sharpen your lawnmower blade in minutes and do the job safely.

1. Safety first - when removing the blade from your lawn mower there are two safety tips to use before you get started.

First, remove the spark plug from both an electric model and a gas-powered lawnmower. This prevents any accidental starts.

Second, keep the carburetor facing up when tipping your lawnmower. This action helps prevent oil and gas spills. By doing this you are keeping your work area a lot safer.

2. Removing the blade - even though the blade is dull, it can still cut skin. Make sure to wear a pair of gloves to protect your hands. Now you can hold the blade with your one gloved hand while the other hand is loosening the bolt. We do not recommend this procedure.


The best way to hold the blade still is to use a good-sized piece of 2 by 4 and jam it in between the blade and the lawn mower housing. This will keep your hand safe while holding the blade still as you unscrew the nut.

If you find that the nut is too tight, spray a little lubricant on it and let the oil sink in before trying again. As you remove the blade mark the bottom side of it. This will help you to put the blade back in correctly.

3. Clean the blade - getting rid of grass and dirt build up or stains lets you see how much damage has been done to the blade and where it has been done. You can use a rag, screwdriver or even soap and water, as long as you get a clear view of the blade edge.

After inspecting the blade, you may find that it is too damaged to sharpen and buying a replacement is the best way to go. If you buy a replacement blade, make sure you know which side goes up and which side goes down.

4. Sharpening the blade- now you are ready to sharpen the blade. Before you place the blade against the grinding wheel, make sure you are wearing protective clothing and face or eye masks. Gloves, long-sleeved shirts, and masks protect you from any flying metal and sparks.

Turn the bench grinder on and double-check to see if you are holding the blade in a comfortable way. This helps make sharpening a lot easier. Position the blade at the correct angle, and move the blade back and forth against the grinding wheel.

Remember to keep a steady hand as you do this. Never change the angle during mid sharpening.

5. Keep the blade cool - while you are sharpening the blade, the grinding wheel will heat up the metal. You will need to keep the metal cool so as not to damage the blade or hurt yourself.

If the blade gets too hot, it may also bend and ruin your cut.

6. Balance the blade - to get a good cut, you will need to balance the wheel. The easiest way to do this is to place a big enough nail horizontally in a vise. Then using the bolt hole, place the nail through the blade.

Once you have that done, assess the blade again. One side may need a little more metal taken off than the other. When you spot the imbalance, return the blade to the bench grinder and remove the excess metal.

You may have to do this more than once.

7. Return the blade to your lawnmower - just reverse the blade removal procedure and use a block of wood again instead of your hands. The key here is to make sure you get the top side up and the bottom side down.

Just do not over tighten the nut or you may not get it off the next time you have to sharpen the blade. Also, you do not want to make it too loose or you may damage your lawn mower or hurt yourself when the blade comes off.

Bench Grinder Jig for Lawn Mower Blades


It is possible to make sharpening your lawn mower blade a lot easier. The real issue in getting the sharpness is getting the angle right. A good bench grinder jig will ensure that you have the correct angle and maintains that angle throughout the sharpening process.

There are a variety of ways to build your jig to make sharpening your lawnmower blade simpler and a lot less stressful. Just click here to see one good example of a jig to sharpen your lawn mower blade.

The inventor used his angle grinder, but it looks like it can be adapted to a bench grinder as well. Who knows, maybe his example will spark some creative ideas in you and you will build the right jig for you.

Lawn Mower Blade Sharpening Wheel

Getting the right grinding wheel to sharpen your lawn mower blade is essential. There are several things to keep in mind as you search for that wheel.

First, you need to determine if your lawn mower uses a ferrous or non-ferrous metal blade. This is essential as grinder wheels are not a one size fit all sharpening tool. Different grinding wheels work with different metals.

Second, once you determine what kind of construction material was used to make your lawn mower blade, you need to pick the right wheel. For steel, you will want an aluminum oxide grinding wheel. The grit you use depends on you and how much metal you need to remove.

For non-ferrous metals, you should use a silicone carbide grinding wheel. Never use a soft metal on a grinding wheel meant for steel or other hard metals. Also, do not forget to inspect the wheels before you use them. Conduct a ring test before sharpening the blade.

Proper Angle to Sharpen Lawn Mower Blades


Getting the correct angle on your lawn mower blade can be a bit confusing. Different handymen recommend different angles for the best cut. The range of their suggestions is between 30 and 60 degrees or points in between.

For finer cuts and a nicer looking lawn, you will want a lower angle. That would put the edge of the blade at about 30 to 40 degrees. Some manufacturers suggest a 37-degree edge is perfect for their lawn mowers.

A lot depends on what you are cutting as well. The type of grass, its thickness and so on. On the other hand, a blade sharpened at 60 degrees may protect against nicks but it will also tear the grass out and not cut it.

Best Bench Grinder for Lawn Mower Blades

There are a lot of bench grinders on the market. Not all are good for sharpening lawn motor blades. It is easy to get the mindset that one bench grinder is as good as another, but that would be a mistake to make. Not all bench grinders are the same.

When you are looking for a good bench grinder to handle your lawnmower blade sharpening, here are some things to look for:

  • You want an 8-inch wheel and not a 6-inch one.
  • A heavy-duty grinder is preferred.
  • ​It needs to be well balanced.
  • ​The quieter the motor the better. This lets you know that there is little friction.
  • Make sure it can be mounted and secured in place.

Some Final Comments

Why pay the money to have a professional sharpen your lawnmower blade when you can do it just as well? By following the steps listed above, you can become a pro at sharpening your own lawn mower blades and get the job done right.

Learning how to have a steady hand will make sure you get the edge just right. Then by practicing good safety, you can do the job without hurting yourself. Once you get a little experience, it shouldn’t take you that long to get the job done.

The other key component to sharpening your lawn mower blade is getting the angle right. If you are not sure you can do a good job freehand style, just build a little jig to help you. The jig should permanently keep the angle you need and make sure you get a perfectly sharp blade every time.

Finally, make sure you are using the right wheel for the job. With the right wheel, you can do any grinding job.

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