How to Balance Lawn Mower Blades + Why It’s Important

When people think about taking care of their lawn mower’s blade, the first thing that usually comes to mind is sharpening. But, what does balancing lawn mower blades have to do with this? What some don’t realize is that sharpening a blade goes hand in hand with its balance. Lawn mower blades typically become unbalanced during the sharpening process when you shave more metal off one side of the blade than the other. Getting your blade back into balance is simple but super important.

How to Balance Lawn Mower Blades

To balance lawn mower blades you can follow these steps:

1. Remove the blade
2. Clean off any built-up gunk or debris
3. Put the blade on a balance using its center hole
4. Assess where the imbalance is
5. Sharpen or grind the blade into balance
6. Brush off and reinstall the blade

Step by Step Guide to Balancing Lawn Mower Blades

Let’s talk in more detail about how to balance lawn mower blades. To get started you will need some equipment.

What you need:

• Your blade sharpening tool (typically a grinder, file, or sharpening stone)
• Safety glasses
• Steel wire brush (for cleaning your blade)
• Wrench
• Blade holder
• Gloves
• Balancer (can be substituted with household items)

Instructions:

1. Blade Removal

   Before you get started, disconnect your spark plug to prevent any chance of the mower starting by accident. You can just pull the spark plug wire off and secure it so it can’t make contact with the spark plug (also a good opportunity to check your spark plug ). Next, tilt your mower on its side making sure the air filter and carburetor are facing upwards so that gas and oil don’t contaminate the filter. Then, hold the blade in place and use your wrench to remove the bolt and blade.

2. Cleaning the Blade

   Brush off the blade thoroughly with your steel brush to remove any debris and chunks of rust that have built-up on the surface of the blade. It is very important to do this because any excess material on the blade will affect its weight/balance. If the blade seems extremely damaged, pitted, or rusted, it may be time to replace the blade.

3. Hanging the Blade

   This is where you get your balancer out and set your blade on it. Most commonly you can find balancers that sit on your workbench, but they also make wall-mounted balancers. In either case, what you need to do is set the blade on it using the hole in its center.

4. Assessing Balance

   Once your blade is set on your balancer, you need to determine which side is “heavier”. If one side of the blade dips, that is the side you will need to alter to bring the blade into balance. If the blade sits perfectly, it is already in balance!

5. Balancing the Blade

   Using your grinder, file, or sharpening stone, sharpen your lawn mower blade  and remove more material from the heavier side. Check the balance again and continue to hone your blade until it rests completely flat on your balance. If, for some reason, your blade has a major imbalance, you can also grind a notch into the backside of the blade to remove material more efficiently.

6. Reinstalling the Blade

   Basically, you’ll just need to reverse steps 1 and 2. Brush any metal shavings off your blade, bolt it back in place, turn your mower right side up, reconnect your spark plug, and you’re good to go!

Why Balance Your Lawn Mower Blades?

You probably never think much about how fast a lawn mower blade spins (up to 216 MPH in case you’re interested). But because they spin thousands of times per minute, it is crucial to have lawn mower blades that are balanced and centered in their rotation. There are many symptoms of unbalanced lawn mower blades , but the most infamous one is excessive vibration. Though you may not think much of it, blade imbalances can cause serious problems. Such problems range from structural damage due to the loosening or breaking of bolts, or engine problems because of stress on the blade shaft and spindle. Blade imbalance can also result in grass with torn edges, and uneven cutting. Keeping your lawn mower blades balanced is just as important as keeping them sharp.

How Often to Balance Lawn Mower Blades

The rule of thumb here is to balance lawn mower blades every time you sharpen them.  The standard for sharpening is once a season or every 25 hours of mowing time. However, as you could have guessed, variables like rocks and big sticks can dull your blade extremely quickly. Still, because of their yin and yang relationship, sharpening and balancing should be done at the same time.

Are New Lawn Mower Blades Balanced?

While you should not sharpen new lawn mower blades, you should check to make sure they are balanced. Even though all of the new lawn mower blades I’ve bought have been balanced, it is worth checking. Nothing is worse than going through the process of installing a new blade and noticing vibration problems afterward. Because it is so easy to do, you might as well make sure your new blade is balanced.

How to Balance a Lawn Mower Blade Without a Balancer

This can be done in a number of ways depending on what you have handy. People tend to disagree about which method is the best, but I’ll describe a few methods that have stood the test of time and you can be the judge.

1. Nail in the Wall Method – For this common alternative to using a balancer, you just need a hammer and a nail. To do this, you’ll need to pound a nail into your wall and set your mower blade by its center hole on the nail. You can then assess which side of the blade is heavy. Mimicking wall-mounted balancers, this will allow you to see which part of the blade you need to grind down.
2. Screwdriver Method – This method is basically the same as the nail method, except here you’ll use a screwdriver through the center of the blade. You can either hold the screwdriver in your hand, or fix it in a vice to eyeball if your blade is balanced or not.
3. Pliers Method – Needle nose pliers can also be used to test your blade’s balance. This method uses the same approach as benchtop balancers. Here, you hold your pliers upright, place the closed pliers through the center of the lawn mower blade, and take note of which way the blade tilts.
4. Socket Extension Method – Another variation of the balancing test on your workbench uses a ½ inch socket extension. To do this, you will need an extension that is longer than your lawn mower blade is wide. Set the extension on a flat surface, and place the blade on top of it perpendicularly. Next, roll the extension one way or another so that the blade is balancing on it. A perfect blade will balance and you will see the extension in the dead center of the blade’s mounting hole. If the extension is not centered in the blade’s mounting hole, you will need to balance the blade accordingly.

How to Balance Riding Lawn Mower Blades

To balance a riding lawn mower blade you just need to follow the same steps as you would for any push mower. However, though the process is pretty much identical to that of push mowers, there is one key difference: removing and reinstalling their blades. Different riding mowers have different requirements but generally involve using ramps/blocks to access the blades, or removal of the mower’s deck.

Overview

Balancing lawn mower blades require the same steps needed to sharpen them, with the addition of one more measurement along the way. This little measurement may seem inconsequential but is actually super important. The best part is, no fancy tools are required! People have been figuring out how to balance lawn mower blades without a balancer since they were invented. Though balancing lawn mower blades falls somewhat into the “close enough” category of measurement, be sure to take the extra few minutes to make your own assessment.