If you notice any uncut grass when running the mower, the blades are probably dull. The blades on a lawn mower will dull over time and must be replaced regularly for the object to work efficiently. With a clean, sharp blade, the grass in your yard will look even more beautiful and you won't have to spend a lot of time tidying it up. Replacing blades is fairly easy and can be done quickly if you know the right way to do it. See step number 1 below for more information.
Step
Part 1 of 2: Inspecting and Removing the Old Blade
Step 1. Lift the mower body to expose the blade
It's important to pay attention to the position of the carburetor and oil tank so you don't spill oil all over the engine, grass, and yourself when you lift it. Generally, the safest way to do this is to flip the mower over to the handle on the back, then either smother it with some kind of weight or ask someone else to hold it down. This method cannot be used for all types of lawn mowers. Therefore, make your own judgment and consult the owner's manual if necessary.
It is best to do this when there is no fuel left in the engine. Wait until the fuel runs out to replace the blades, or drain the fuel tank with a siphon hose. Generally, siphon pumps are sold freely at hardware or automotive supply stores. This will prevent fuel from spilling onto the engine body
Step 2. Remove the starter spark plug
This is done as a precaution and to prevent a short circuit or electric spark due to oil and fuel spills to the starter spark plug. If you position the machine correctly this shouldn't be a problem, but just do it just to be safe.
Step 3. Remove the blade retaining bolt
Use a properly sized socket wrench, then remove the holder while using your other hand to keep the knife from moving. Do not throw away the bolts or devices used to hold the blade in place as they can be reused.
Pay attention to the position of the blade when removing it. You must install the new blade in the same position. Usually, the sharp part will be positioned counterclockwise during the assembly process. Again, this method does not apply to all types of lawn mowers. So, pay attention to the position of the blade on your machine and install a new blade in the same position
Part 2 of 2: Installing New Blades
Step 1. Purchase a replacement blade
Replacement blade kits for lawn mowers usually sell for just a few hundred dollars at a home supply or hardware store. This kit includes a new sharp blade and some spare bolts. If your blade is completely dull, it's best to buy a new one.
- Some lawn mowers have a cover at the bottom that separates the two small blades, while some newer models use a single, long blade that looks like a ruler. Turn the mower over to check the type of blade used or ask the hardware store staff to find a blade that matches your brand of lawn mower. Also check the machine manual if there is one.
- Alternatively, you can also reuse an old re-sharpened knife if it still looks good. If the blade is completely dull and uneven, it's best to buy a new one.
Step 2. Install the new blade in the correct direction
Position the new knife in the same position as the old knife, then replace the retainer and bolts, or use a new holder and bolt of the appropriate size. If you have a machine manual, there should be information on the size specifications of the wrench for tightening the bolts. Otherwise, just make sure you don't tighten the bolts so that the blades bend, as this can make the lawnmower vibrate when in use.
- Lawn mower blades may be made for a particular brand of engine or for all engine brands. Make sure the new blade is the same length as the old blade. Also make sure the engine frame spacing is appropriate. Tighten the blade of the new knife carefully as it is much sharper than the old one.
- It's a good idea to wear thick mechanical gloves when doing this to keep your hands safe. In addition, it is highly recommended to use a small piece of wood to hold the knife from moving when it is installed. You can slip a small piece of wood between the blade and the frame to keep the object from turning.
Step 3. Check the blade again
Make sure the blade is properly seated and doesn't wobble as you move it up and down. Remove the weight or object used to hold the mower, then wait 30-60 minutes for the oil to drop back into the tank and prevent damage to the engine motor. Check the oil before using the engine to make sure it is sufficient.
Step 4. Refill the fuel tank and double check before using the engine
Check the air filter to make sure oil is not seeping into the filter foam, then reattach the starter spark plug wire.
