Your mower will see significant use during the growing season, peaking in the summer months, and it also benefits from having its blades sharpened regularly throughout the year. If you notice that the ends of your grass look frayed or torn after mowing, this may be a sign that your cutting blades have been sharpened.
There are several ways to sharpen blades at home, either using hand tools or power tools. The method you choose may depend on the tools you have available, or your confidence and experience using them.
If you want to know how to sharpen lawn mower blades, we’ll take a look at how often you need to do it and get advice from experienced lawn care professionals on how to get the job done.
When to sharpen lawn mower blades
How often you need to sharpen your lawn mower blades will be determined by how often you mow and the size of your lawn. A good rule of thumb is to sharpen your mower blades twice a season, or after 25 hours of use. If you have a large lawn and mow your lawn every week, this time can add up quickly. It may also be helpful to sharpen the blades when you winterize your lawnmower, so they are ready to use when you start mowing again in the spring.
Small mower blades, such as a home electric lawn mower, can be sharpened at home, but sharpening the blade yourself requires confidence in the tools and good attention to detail. The alternative is to use a professional service.
Best way to sharpen lawn mower blades
Lawn mower blades can be sharpened in several different ways, including using a metal file, a drill-powered blade sharpener, an angle grinder, or a bench grinder. For all methods, it is best to remove the blade from the mower, and for most, it should be held in place with a vice.
David Parker, owner of Reliable Lawn Maintenance Macon in Georgia, recommends six key steps for how to sharpen mower blades at home — and he has some top tips for putting safety first when completing the job.
- Before you start, disconnect the spark plug to ensure you don’t accidentally start the mower. Wear safety gloves and eye protection.
- Use the wrench to remove the mower blade. Note the direction of the blade to reinstall it correctly.
- Clamp the blade in a vice or with a piece of wood to prevent movement during sharpening.
- Use a metal file or angle grinder with a sharpening tool to sharpen the cutting edge. Follow the original angle of the blade, and maintain a constant bevel.
- After sharpening, check the balance of the blade. If one side feels heavier, continue sharpening until the blade is balanced.
- Carefully replace the sharp blade, making sure it is oriented correctly.
David Parker is the owner of Reliable Lawn Maintenance Macon, which provides lawn maintenance services to homeowners in Macon, Georgia.
How to sharpen lawn mower blades by hand
To sharpen blades using a metal file, attach it to a vice with one cutting edge facing up. “Use a 10-inch file or abrasive stone,” recommends Ryan Farley, CEO of LawnStarter.
“Hold the file at a 45-degree angle and start at the top of the blade,” he adds. “Push down in one direction, place the file at the starting point, and repeat. Don’t move the file back and forth.”
A clean, sharp 10-inch file, like this one on Amazon, should be able to sharpen a typical domestic lawn mower blade in 50 strokes. The level of sharpness you are aiming for is a sharp “butter knife”.
To check the balance of the blades, use either a blade balancer, also available at Amazon, or use a nail, screwdriver, or broom handle as an axis. It is important to ensure that the balance is correct, as if you start cutting the grass again with an unbalanced blade, it could cause damage to the mower. The blade can then be reattached to the mower, making sure it is in the correct direction.
Ryan Farley is CEO of LawnStarter, a lawn care service founded in 2013 and headquartered in Austin, Texas.
How to sharpen lawn mower blades with a grinder
When it comes to using power tools with a sharpening tool, make sure the blade is held securely in place and that you have the appropriate protective equipment.
Align your tool with the angle of the blade and keep that angle consistent as you move the grinding disc along the mower blade. Just apply light pressure to the blade and only a few passes will likely be needed to achieve butter knife-like sharpness. You don’t want to make too many strokes and make it too sharp, as this makes the blade more likely to chip easily during use. Repeat this process on both edges of the blade.
However, Jeremy Yamaguchi, CEO of Lawn Love, says the grinder is “the quickest and most efficient way to sharpen lawn mower blades.”
This may be too advanced a task for many DIY blade sharpeners, he adds: “Since this involves handling dangerous tools and creating sparks, you have to be really careful – and I would recommend getting someone experienced to do this if you are.” Don’t feel comfortable using a bench grinder.’
After sharpening the blades with the grinder, check the balance as described previously before returning the blades to the mower.
As CEO of Lawn Love, Jeremy Yamaguchi helps homeowners find high-quality, reliable lawn care. Specializing in technology and using industry expertise, he intends to revolutionize the lawn care industry.
Can you sharpen lawn mower blades without taking them off?
It is possible to sharpen lawn mower blades without removing them, however this will make the job difficult and it is always recommended to remove and secure the blade.
When it comes to how to sharpen lawn mower blades without removing them, you will need to use a block to stop the movement of the blades as well as ensure that the mower is properly supported on its side. Then you can grind the top face of the blade into place – the side that faces the mower’s engine. You will need to act slowly and work carefully, as you will not be able to check the balance afterwards.
Is it worth sharpening lawn mower blades?
It is always beneficial to keep your mower blades sharp, for the overall health of your lawn. Sharp blades will ensure your mower cuts cleanly, rather than slicing and tearing – which can lead to poor health, increased risk of disease, and ultimately bare spots in the lawn.
A mower with sharper blades also uses less fuel and can have a longer life. Not keeping your mower blades in top condition will be a lawn care mistake that can affect your lawn and machine.
Sharp blades and proper mower maintenance are only a small part of keeping your lawn healthy. A regular lawn maintenance regimen should include tasks such as aeration, raking, supervision and feeding. All of these things will combine to help make your lawn green and thick for you and your family to enjoy.