New Mower Blades: To Sharpen (or Not?)

Lawnmower blades need to be sharp to properly cut grass. This is what you need to know about NEW mower blades.

If you’ve recently purchased new mower blades, you may be wondering whether or not they need to be sharpened before use.

Sharpening NEW mower blades is not recommended for several reasons, the main reason being that most new mower blades are pre-sharpened at the factory. (but…)

Although new mower blades typically don’t require sharpening before their first use, there are exceptions to the rule that may not be obvious and I’ll explain that a bit more here.

There are common mistakes to avoid when installing new mower blades, I have seen them made countless times in my 25 years or maintaining power equipment.

The goal of this article is to answer your question, explain why, and to share other important new mower blade best practices.

Lawnmower blades that are dull, damaged, or improperly sharpened affect mower performance and can affect the overall appearance and health of your grass.

The Importance of Sharp Lawnmower Blades

When lawnmower blades are dull, they tear and damage the grass blades rather than cutting them cleanly. This can result in ragged and uneven edges, which in turn can make your lawn look unkempt and unhealthy.

Damaged blades can cause stress to to your lawn, making it more vulnerable to pests and disease.

Sharp lawnmower blades, on the other hand, cut through grass blades efficiently, producing clean edges that promote healthy growth.

Signs that Your Lawnmower Blades Need Attention

When mower blades need to be sharpened there are typically several signs telling you it’s time.

The first is the lawn itself, it may appear less healthy or start to look ragged, uneven or frayed. A dull mower blade will rip the grass apart, not cut it, which isn’t ideal for optimal growth.

The next sign the blades need sharpening will be related to mower performance. The mower may become harder to maneuver and leave larger clumps of grass behind it while you mow.

In extreme cases a neglected mower blade can cause the mower to vibrate. As it becomes worn over time, the blade will lose its balance and no longer spin evenly.

Don’t ignore the signs, they can lead to mower damage. I’ve even seen the vibration of a worn blade become so severe it bent the engine shaft, destroyed the bearings and caused excessive amounts of smoke to billow from the exhaust.

Advantages of Sharpening Your Lawnmower Blades

Sharp blades can save you time and money in the long run.

Dull blades require more passes over the grass to achieve the same level of mowing, which can lead to increased wear and tear on your lawnmower and more frequent need for maintenance or replacement.

Sharp blades can also help to improve the fuel efficiency of your lawnmower.

Dull blades require more power to cut through grass, resulting in higher fuel consumption and increased emissions.

Sharpened blades, on the other hand, help to reduce the amount of fuel needed to mow your lawn, making it a more environmentally friendly and cost-effective option.

Pros and Cons of Replacing Your Lawnmower Blades

PRO – Improved cutting performance: Over time, lawnmower blades can become dull, which leads to a less efficient and effective cut. Replacing the blades will ensure that your mower is cutting effectively and evenly.

PRO = Increased safety: Dull or damaged blades can cause the lawnmower to vibrate, leading to an increased risk of accidents or injury. By replacing your blades, you can ensure a smoother and safer mowing experience.

PRO – Better lawn health: Dull blades can tear or shred grass, which can lead to a higher risk of disease and insect infestations. By using sharp blades, you can ensure a clean cut that promotes healthy grass growth.

PRO – Reduced wear and tear on the lawnmower: When blades are dull, the engine has to work harder to cut the grass, which can lead to increased wear and tear on the mower.

By replacing the blades, you can extend the life of your lawnmower.

CON – Cost: Depending on the type and brand of lawnmower, replacing the blades can be an additional expense. This is a maintenance cost that is necessary to ensure the longevity of your equipment, so is worth it (in my opinion).

CON – Time: Replacing the blades can take some time, depending on the model of the lawnmower and your experience level. It is a relatively simple task that can be completed with basic tools, and I recommend you learn it.

CON – Risk of injury: While replacing the blades is generally a safe task, there is always a risk of injury if proper precautions are not taken.

Always follow the manufacturer’s instructions and use protective gear, such as gloves and eye protection, when working on your lawnmower.

Signs that Your Blades are Beyond Repair

#1 – Excessive wear: When the blades are worn down excessively, they may be too thin to be effective in cutting your grass. You may notice that the blades are much thinner than they should be, or that they are bent or warped due to use.

#2 – Dents or cracks: If the blades are dented or cracked, they are no longer able to cut the grass effectively. This can happen if the mower has hit rocks or other hard objects in the yard.

You may also notice that the blade is missing chunks or pieces. (Safety Issue, I recommend you replace them immediately!)

#3 – Uneven cut: If the mower is leaving behind patches of uncut grass or if the grass is being cut unevenly, it may be a sign that the blades are bent or damaged. This can be caused by hitting hard objects or from general wear and tear.

#4 – Vibrations: If the mower is vibrating excessively while in use, it could be a sign that the blades are damaged or out of balance. This can be dangerous and can cause damage to the mower over time.

#5 – Reduced efficiency: If the mower is taking longer to cut the grass or is leaving behind clumps of grass, it may be a sign that the blades are dull or damaged. This can be caused by excessive wear or damage from hitting hard objects.

Testing Your New Blades for Optimal Performance

#1 – Do a test cut: Before you start mowing the entire lawn, do a test cut on a small section of grass to ensure that the blades are cutting evenly.

This will give you a chance to make any necessary adjustments before starting the full mow.

#2 – Check the height: Make sure the blades are set to the correct height for your lawn type. Different grasses have different ideal mowing heights, so be sure to consult your mower’s manual to set the blades to the proper height.

#3 – Monitor the cut: As you begin mowing, monitor the cut of the grass. The blades should be cutting the grass evenly and cleanly, without leaving behind any uncut patches or causing excessive vibration.

#4 – Look for clumping: If you notice that the mower is leaving behind clumps of grass, it may be a sign that the blades are not cutting effectively. This can be caused by dull blades or blades that are not properly adjusted.

#5 – Check for wear and tear: After mowing, inspect the blades for any signs of wear and tear. If you notice any issues after the first test cut, service the blades again before the next mow.

I find that, most of the time, the initial sharpening works well but every once in a while the blade metal doesn’t retain a sharp edge, depending on your lawn condition and blade quality.

How to Extend the Lifespan of Your Lawnmower Blades

#1 – Keep them sharp: Sharp blades are more efficient at cutting grass, which reduces wear and tear on the blades. Sharpen the blades regularly, or have them professionally sharpened, and you will save money in the long-run.

#2 – Keep them clean: After mowing, clean the blades with a wire brush or hose to remove any grass clippings, dirt, and debris. This helps to prevent corrosion and damage to the blades.

I like to use a simple paint scraper and quickly tip the mower and scrape each blade once or twice. That’s all it takes!

#3 – Avoid hitting hard objects: Hitting rocks, stumps, and other hard objects can cause dents and cracks in the blades. Be aware of your mowing area and avoid hitting anything that could damage the blades.

#4 – Adjust the height: Make sure the blades are set to the proper height for your lawn type. I find that mowing too low causes more wear and tear on the blades than using a higher cut height.

#5 – Replace damaged blades: If you notice any signs of wear or damage, such as dents or cracks, replace the blades before the next mow. Using damaged blades is a health risk, can cause damage to the mower, and can result in an uneven cut.

#6 – Store properly: Store your mower in a dry, covered area to prevent rust and damage to the blades. Keep the blades relatively clean and dry before storing.

By following these tips, you can extend the lifespan of your lawnmower blades, which can save you money in the long run by reducing the need for frequent blade replacements.

Should You Sharpen New Mower Blades