Far too many people tend to overthink the process of replacing a Lawn Mower Blade and determining whether or not you should sharpen new blades is a classic example of this.
So, do lawn mower blades come sharpened? Yes, they do. Most, if not all, new lawn mower blades are ready to use right out of the box. They might not seem sharp to the touch and might even feel a little blunt. That is how they were designed, built, and delivered straight from the factory.
I’m assuming you googled whether or not lawn mower blades come sharpened because you have just picked up a new set or are about to. If that’s the case, you’re in luck. Keep reading for a bunch more information regarding your new lawn mower blades.
Do You Need to Sharpen New Lawn Mower Blades?
The question is often debated whether it is actually necessary to sharpen new lawn mower blades. After all, why do new mower blades seem dull? First impressions of a new blade would seem they need to be sharpened because they appear rather dull or blunt when they have the factory paint on them.
The paint on new lawn mower blades is there to prevent rusting, among other things and does not actually have an adverse effect on the performance of new lawn mower blades. In fact, after the first couple passes mowed with the new blades, the paint will be worn off.
I understand the underwhelming “sharpness to the touch” of new blades doesn’t exactly give the buyer confidence, especially for the less seasoned grass cutters out there. You will find that they are sharp enough for a significant uptick in performance from the dull blades you replaced!
While this is also not common, I have seen examples of people who choose to sharpen their new lawn mower blades and then subsequently spray paint them. The logic of that is naturally flawed. The spray paint job, which we assume is to prevent things like rust developing, will come off after the first few passes with the mower.
All you really need to do is take those new mower blades out of the box, bolt them on your mower and enjoy the mow! When you do eventually decide to sharpen the blades – try not to change the angle that blade was originally sharpened at. That is an important detail we will expand on later.
How To Know When Lawn Mower Blades Need Sharpened?
Now that we cleared up that new lawn mower blades come sharpened – let’s talk about when you’ve put some miles on those bad boys and they get a little dull.
It is almost always the case that the lawn itself will tell you when to sharpen your mower blades. The best way to go about that is to take a blade of grass after you have just cut it and do a brief inspection of the quality of the cut.
If you establish that it is a nice clean cut at the top of the blade of grass, then your blade is in good shape. If you find that the blade of grass is frayed at the edge, as if it was torn instead of cut, then it is most likely time to consider sharpening your mower blades.
Most experts agree that grass is more prone to disease when it has a poor quality of cut. Secondly, your lawn is probably going to have a brown tinge to it two or three days after you have cut – if the cut is not clean, and let’s be honest, that’s the LAST thing people who are passionate about their lawn want.
It is also a good idea to sharpen your lawn mower blades before the first cut of the mowing season. This will be beneficial for the very start of spring when you’re cutting the delicate grass just beginning its growth spurt out of winter.
If you are decent at avoiding roots, rocks, and other obstacles that dull your blades our quicker, you will probably only have to sharpen the blades two or three times during the growing season.
How To Sharpen a Lawn Mower Blade
REMINDER – Before you get started, make sure there is no way the engine can fire on you while removing a blade. Do yourself a favor and remove the spark plug wire. This step is extremely important.
One way to sharpen your mower blade is with a metal file. It is a common way to go about it and is also generally safe. Firstly, you can put the blade in the vice or clamp, which holds it firmly in place if you tighten it properly.
It is very important to trace the angle on the blade, to ensure that it stays the same. You should only ever stroke the blade in one direction when doing the sharpening. Keep going at that same angle until you get all of the nicks out of the blade.
If you do have a cordless drill you can actually get an attachment on it to help sharpen your blades quicker and make the process less manual. You could also use a handheld angle grinder or bench grinder. Keep in mind each of these options can be more efficient, but add additional safety hazards.
Balancing New and Used Lawn Mower Blades
New lawn mower blades should come balanced from the factory. The might not be perfect, but they will definitely be good enough to get the job done. You really only need to worry about balancing blades when you sharpen them yourself.
Whatever options for sharpening you choose, it is recommended to then go through the process of balancing your blades. Luckily, lawn mower blade balancers are generally cheap and simple to use. You simply place the blade on the balancer and further sharpen the side of the blade that hangs lower until the blade is balanced in the center.
The point is that the same amount of sharpening work needs to be done on both sides of the blade. One side of the blade should not be heavier than the other. An unbalanced lawn mower blade could cause damage to your machine over time and provide a less than desirable results when cutting the grass.
Things to Look Out For When Putting On New Lawn Mower Blades
Believe it or not, there is actually a wrong and right way to put a new lawn mower blade on. Installing a lawn mower blade the wrong way could be potentially damaging to you, your lawn mower, and most importantly, your lawn (just kidding).
The most common mistake when installing a new blade is putting it on upside down. Blades that are installed upside down are not going to be cutting your grass, they are going to be tearing and ripping it off. Which as we discussed earlier, is bad for your lawn.
Most Lawn Mower Blades come with a wing and that wing should always be pointed up, not down. When the wing of the blade is pointed down, it makes you extra prone to catch sticks, rocks, and other projectiles when mowing. This is not ideal for obvious reasons.
Catching projectiles with your blades can do more than be a safety hazard and dull your blade, you could damage your flywheel key. That is certainly a problem you want and need to avoid and thirdly you could bend your crankshaft. That is obviously a worst-case scenario though. It is still a potential scenario nevertheless.
Always double-check that your blade is tightened to your mower correctly. I highly recommend using a torque wrench and following your particular mower’s manual when doing so.
You may or may not notice your lawn mower giving you signs that the blade is installed correctly. This is why it’s important to always make sure you’re inspecting the grass your cutting after every few passes.
In conclusion, you don’t need to sharpen new lawn mower blades, but you do need to make sure you install them correctly.