Have you been mowing along and then all of a sudden launch a rock out from underneath your lawn mower? Are you tired of having to run over the same patch of grass more than once to cut all the blades of grass or to get an even cut?
Your lawn mower blade may need to be sharpened or replaced.
You don't need to replace your blade every time you hit a rock or it isn't cutting correctly: it may need to be sharpened. However, if you do not sharpen the blade properly, it may cause the blade to become uneven in weight and cause damage to the lawn mower engine itself. So we will focus on replacing the blade altogether in this instructable,
Not every push mower is the same. There may be a few difference in some components but the general idea is the same. Please ensure that your lawn mower is support properly while you are working underneath so it does not fall on you while you are applying pressure loosening or tightening the bolt that holds the blade on. Also allow sufficient cooling time after running your mower as components may be hot!
Step 1: List of Materials
Of course you need a lawn mower to work on
Replacement blade (should include all hardware, compare this with your old blade to ensure you have everything you need)
Wrench or socket to fit attaching bolt
2 cylinder blocks or something similar to put lawn mower on.
Safety goggles or glasses
Step 2: Getting to the Bottom of Things
First, you need to be able to get to the underside of your lawn mower. Use something that is sturdy enough to support the weight of your particular mower and allow you access to the blade underneath. You also want to ensure that the support is stable and does not allow for movement as you will be applying pressure to the attaching bolt.
Step 3: Remove the Old Blade
Once your mower is situated to where you have access to the underside, the next step is to remove your old blade.
Picture 1: Using the correct size wrench or socket, turn your attaching bolt counter clockwise to loosen your bolt. Remember, lefty loosy/righty tighty. Your blade will turn as you turn your wrench, so you can use your hand to hold the blade from turn while loosening.
This is where your gloves and goggles may come in handy. If you are directly underneath as I am in the picture, you may end up with grass and dirt in your face. And the blade may still be sharp so the gloves protect your hands.
Picture 2: Pay attention to your hardware when you remove your parts to ensure you know what pieces need to be used when putting the blade back on. This also a check to ensure that nothing is broken or needs to be replaced besides the blade.
Step 4: Selecting Your New Blade
Unless you know what blade you need already, most of the time it's easier to take your old blade to the store to compare with. Most of the time you will just buy a universal fit blade. Of course there are different types of blades for different mowers so if you are just unclear of which one you need, it is better to ask the question with a store associate.
Picture 2 is a picture of my old blade and picture three is the new one. These just show you one thing to look for.
Step 5: Putting on the New Blade
Once you have the new blade, it is time to install it. One thing you want to make sure is that you do not install it upside down. If you do it will not hurt anything, it just won't cut your grass right. Most blades that I have seen are fool proof and are labeled as shown in picture 1. This of course is the bottom side of the blade so the other side is the side that goes toward the mower.
Once you have your blade oriented properly, install the attaching bolt back into your mower shaft through the blade and tighten. Ensure you have your blade properly fit with your studs through the holes or notches. These studs keep the blade from moving around when the mower is on.
Once aligned, tighten your attaching bolt! You are done!!
Step 6: Time to Mow
It's time to put that new blade to work. After starting your mower and you notice a very bad wobble, immediately shut down the mower. sometimes what happens is the blade gets loose if not tightened all the way and starts wobbling. Just get back underneath and tighten everything.
Picture 1 is before I changed my blade.
Picture 2 is after.