You can only sharpen a lawn mower blade 5 to 6 times before it inevitably breaks. This means you can get between 100 to 200 mowing hours out of your blade before you need to replace it.
In this article we will explain everything you need to know about mower blades: how many times they can be sharpened, how to actually sharpen them, and more!
Why does a lawn mower blade need to be sharp?
It might seem like a silly question, but there are multiple practical reasons why you need to keep your blade sharp. A razor-sharp blade will cut cleanly through the blades of grass without ripping or tearing, which gives your lawn a smooth, professional look.
However, what you may not realize is that dull blades are not only inefficient but also put stress on the blade shaft and motor. Over time, this can reduce the lifespan of your mower, which can be very costly to repair or replace.
How do I sharpen a lawn mower blade?
- Gather the following equipment. You’ll need a wrench, or ratchet and socket for removing the blade, and a file, grindstone, or angle grinder for the sharpening.
- Detach the blade by unscrewing the nut and remove the washer that holds the blade to the drive shaft.
- Clean the blade thoroughly. Use a scraper to remove grass, and for more stubborn dirt apply penetrating oil for 30 minutes before wiping with a cloth.
- Sharpen the blade. Use your preferred sharpening tool, e.g., a file, angle grinder or grindstone. Ensure to wear safety glasses to protect yourself from sparks.
- Check that the blade is aligned properly. Sharpening can remove more metal from one side of the blade and result in an uneven cut. Balance the blade on a screwdriver and adjust until it is perfectly balanced.
- Replace the blade. Put the sharp blade back into the mower and fasten the nut and washer in place using a torque wrench.
How many times can I sharpen a lawn mower blade?
Eventually, you’ll find that your blade has reached the end of its life and can simply not cut one more blade of grass. Fortunately, most blades can survive 5 – 6 rounds of sharpening before they give up. This is around 30 mowing hours per round of sharpening.
This means that in the best-case scenario, most blades can last 150 to 180 hours before you’ll have to replace them.
Should I sharpen or replace my lawn mower blade?
Even if you kept your blade in great condition, eventually you’ll need to replace it. When your blade completely loses its edge, develops large cracks or dents, it’s time to retire it permanently.
Fortunately, blades are inexpensive, easy to replace, and readily available from most hardware stores or directly from the manufacturer. Depending on the type of blade, you can pick one up for around $20 – $40.
Do different lawn mower blades last longer?
Generally, low lift blades last longer than their higher lift counterparts. This is because they produce comparatively lower suction due to their design. Lower suction results in less debris coming in contact with the blade, extending its lifetime.
Additionally, low lift blades are usually smaller than other mower blades, and therefore exert less strain on the mower. This means that you may get more mowing hours out of your mower in the long term by using low lift blades.
How can I tell if my lawn mower blade needs to be sharpened?
If you start to notice the following things when mowing, your blade might have lost its edge and need sharpening.
- If your blade is dull, it will cut unevenly and may suffer from more damage as a result.
- As you cut, you start to notice it takes longer and longer to cut the same area of grass, and the grass length becomes uneven in places, requiring you to redo areas you’ve already cut.
- The grass itself may be torn or pulled from the ground rather than sliced cleanly. This can pull chunks of dirt from your lawn, leaving it an unsightly mess.
- It might become more difficult to push the mower and may stall more frequently as it struggles to cut without grass getting stuck in the blade.
How does a lawn mower blade become dull?
Over time, many millions of blades of grass will be split by a mower blade. While one blade of grass won’t have much effect on a blade, the accumulation of countless impacts on a blade causes it to lose its edge.
Compounding this is the small stones, sticks and other debris that will hit your blade from time to time. These can cause dents, nicks, and cracks to form on your blade, causing it to become dull faster than usual.
How much does it cost to sharpen a lawn mower blade?
If you have all the equipment and skills, it’ll only cost your invaluable time to sharpen it yourself. If you’re just too busy however, it’s relatively affordable to pay for mower repair services.
Sharpening shack provides sharpening services for only $10 per blade if you remove them yourself, or $15 if you require them to remove the blade for you. This could be a viable option for you if you need to purchase tools to sharpen the blades by yourself.
How do you keep lawn mower blades sharp?
Now that your blade is sharp enough to shave with, you’ll want to maintain that razor edge as long as possible to get the most out of your mower.
Remove any rocks, branches, or other debris from your lawn before cutting, to avoid unnecessary deterioration of the blade.
To prevent rusting, always remember to clean your blade after use with denatured alcohol and a cloth. Store your mower inside a clean, dry garage under a tarp for best results.
Use a low-lift blade, as they remain sharper for slightly longer than high lift blades.