How To Sharpen Lawn Mower Blades By Hand

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If your lawn mower is starting to tear grass instead of cutting it smoothly then you will definitely need to sharpen the blades. Often people take the blades for granted and never pay any attention to them because they can perform for such a long time without any problem, forgetting that once they become blunt they will not be able to do any good job. On that note it is very essential that you sharpen the blades before you go through the whole expense of a buying a new blade. Sharpening the mower’s blades be an often practice to ensure that it cuts grass properly in each and every pass you make. This is how you can sharpen lawn mower blades with less effort.


  • Prevent the mower from starting unintentionally by disconnecting the spark plug: the injury that can come from a lawn mower starting on its own is very huge so preventing any chances of it starting without your knowledge should be the very first thing you work on. There is a protruding wire on the front or side of the engine and once you disconnect it, you will more than sure the mower will not start accidentally.
  • Protect yourself: prevention is always better than cure so even if you are sure that the mower will not be starting on its own, you need to protect our hands and eyes by wearing heavy leather gloves and safety glasses. Just in case anything happens you will have completely nothing to worry about.
  • Find access to the blade: tilt the mower to the side but carefully to prevent oil from flowing into the air filter and carburetor. After turning it on the side you will find it easy to see where the blade is located.
  • Label the bottom side of the blade: to avoid any mistakes when replacing the blade, it is best to label which the bottom side of the blade is before you even think about removing it. The moment you re-install the blade with the sides mixed up, it will still not cut any grass hence putting all your sharpening efforts to waste. This will take just a minute of time but will save a lot of your effort so be mindful to do it.
  • Work loose the blade’s bolt:use a piece of wood to stop the blade from moving while you untie the bolt to make it easier for you to remove the blade. Place the piece of wood right in the middle of the deck and blade.
  • Properly clean the blade:after getting the blade out, it will definitely be caked up with a lot of grass and debris so you need to clean that off first. If it’s too much dirt and debris you can scrape it off with your hands and if it does not seem to come off you can wash it off with warm soapy water and dry it later with a dry cloth.


Now that you have for blade ready for sharpening there are two ways in which you can do it, you can either do it by hand or use a machine. Let us look at the two ways in which you can sharpen the blade.

Sharpening the blade by hand


Securely fix the blade to your working area: hold the blade in one place with a strong clamp so that it is very easy for you to sharpen it. Place some papers on the working area and put the blade on top so that you can easily clean away the mess later. Make sure to position the blade where you will feel comfortable to sharpen the blade for some minutes.

Sharpen with a grinder:

  • Wear safety glasses to prevent tiny pieces of metal from falling to your face or into your eyes.
  • Take the blade in your hands and starting sharpening with the grinder but try as much as possible to maintain the same angle that you found on the blade. Also be gentle on the blade because you might instead end up spoiling it instead of sharpening it.

Sharpen with a file:

  • Hold the blade down and file the blade with the exact same angle that the blade is in already. Turn to the opposite edge and do the same as well. most blades are sharpened at an angle of 40 degree or 45 degree but you will find some differing so make it a point to follow just what your blade angle is.
  • Fix the blade back, put the blade back just as you found it and apply a lubricant on the bolt to avoid corrosion. The bolt should be very tight, with a ratchet you can be able to tighten the bolt well. This is to prevent any accidents when the machine starts.
  • Since you marked your blade you will not get confused with the side that should be facing down or up but in case you did not label yours check the manual and be sure of how the blade has to be installed.

Sharpening with a machine:

  • When sharpening with a machine you need to take extra precaution, cover your whole body up in clothes, wear safety glasses and put on gloves.
  • With the help of a belt sander you can sharpen the blade, all you have to do is rub the blade at an angle against the sander and the blade will be sharpened due to friction.
  • Wait a few minutes for the blade to cool before touching it and putting it back into the mower.

Tips to keep your lawn mower blades sharp for long

  • It is advisable not to take too long without sharpening the blades, you should sharpen the blades at least after every two or three mowing sessions. Also how the mower cuts grass will help you determine if you have to re-sharpen the blade so always take note of that.
  • Cracked blades should be replaced, it makes no sense trying to sharpen a blade that is already too damaged you will only be wasting your effort.
  • Always check and ensure that the blade is well balanced before use, if the blade does not balance the mower will not perform well and damage will caused to the inner parts of the mower.