Changing lawn mower blades is a simple procedure that will take less than half an hour if the right tools are already owned.
The tools needed are in the second picture.
From left to right:
Sharp blades (see note), work gloves, ratchet and socket or a wrench (see note)
Sharp blades are not needed. If there is no spare sharp set of blades the time to change the blades will increase significantly because time will need to be added in order to sharpen the dull blades once they are taken off.
The ratchet and socket will be easier to work with than a wrench, but a wrench will work in the absence of a ratchet and socket.
Step 1: Finding a Place to Change the Blades
Depending on the type of mower being used, different places will be better than others. For example, a small push mower can just be flipped on its side on top of a cement pad after the oil and gas has been drained.
For a mower parked on top of a raised piece of ground it is mandatory to use the parking break.
1. Find a place to park.
2. Switch the parking brake to the "On" position as seen in the second picture.
3. Turn the engine off and let the mower cool if it is hot.
4. Place a block in front of and behind a tire as seen in the third picture.
WARNING: If steps 2 and 3 are not followed the mower could roll down hill and cause injury.
Step 2: Find What Size Tool Is Needed
1. Place the socket onto the ratchet as seen in the third picture.
2. Crawl under the deck and put the socket and wrench onto the bolt like in the fourth
picture. If the socket does not fit onto the bolt try a bigger sized socket. If the socket fits
onto the bolt but does not catch when turned, try a smaller sized socket. When the
socket fits snugly onto the bolt, the right socket has been found.
Step 3: Taking Off the Blade
1. Once the right socket is found, turn the ratchet's switch to the right as seen in the
2. Place the ratchet and socket on the bolt and grab the the blade with the other hand as
seen in third picture.
3. Twist the ratchet counterclockwise to loosen the bolt. Once the bolt is loose enough,
loosen the bolt by hand, continuing to turn counterclockwise as seen in the fourth
4. Skip this step if there is only one blade.
Crawl out from under the lawn mower deck and place the pieces in a safe location
where they will not be lost as seen in the fifth picture. Repeat steps 2 and 3 again
until all the blades are off.
Step 4: Switching the Blades
CAUTION: Some lawnmowers that have more than one blade will sometimes have blades of different lengths. Pay careful attention to make sure the spare blade is the same length as the blade it is replacing.
1. When done taking the blades off, crawl out from under the lawn mower deck and place
the blades onto a cement or gravel surface as seen in the first picture.
2. Take the blade off as seen in the second picture
3. Put the new blade on, making sure that the side with the long edge is facing the sky
as seen in the third picture. A way to check to make sure the blade is oriented correctly
is to have the sharp edges be doing the cutting if the blade turns in a clockwise
motion while looking at it from the top, like as seen in picture one.
4. Repeat steps 2 and 3 until all the blades are changed.
Step 5: Putting the Blades Back On
CAUTION: Because some blades are different lengths, when putting the blades on, make sure to place the same length blade where it was originally at.
1. Crawl under the lawn mower deck with the correct length blade and insert the bolt
into the hole (first picture) as seen in the second picture.
2. Hand tighten the bolt clockwise. Once the screw is hand tightened you will need to
use the ratchet or wrench.
3. Flip the ratchet switch to the left as seen in the third picture.
4. Place the socket onto the bolt and grab the blade with your free hand and turn
counter clockwise until you can no longer turn the ratchet as seen in picture four.
5. Repeat steps 1, 2, and 4 if there are addition blades to be put on.
6. Turn the mower blades in a circle a few times to make sure the blades do not
catch each other. If they catch, the proper length blades were not installed and the
blades will need to be with ones of the correct length until the blades can freely turn.
Step 6: Clean Up
1. Crawl out from under the deck of the lawn mower.
2. Pick up the blanket or rug if one was used.
3. Place tools back into the tool box or tool chest.
4. Remove the blocks from the tire as seen in picture one.
5. Turn the parking brake to the off position. The off position for the parking brake can be
seen in picture two.