How to sharpen lawn mower blades?


I'd like to know how to sharpen lawn mower blades. I noticed that my mower is not cutting well but I don't want to buy a new blade or buy a new mower. Can someone tell me how to remove lawn mower blade and sharpen it?

q how to sharpen lawn mower blades
  20 answers
  • on Dec 04, 2018

    Remove the blade and pick up a sharpening stone and blade oil from a hardware store. I'm not especially great at it, but I've had success following the original cut angle on the blade and working the stone in smooth circles till all the rust, grass mess and rock dings are removed and the blade looks sharp.

    Good luck

  • Gk Gk on Dec 04, 2018

    Some hardware stores offer mower blade sharpening. You take off the blade and bring it into the store. We keep two sets of blades so that while one blade or set is getting sharpened we have the other set to put on the lawn mower. It looks pretty easy to get that blade off-looks like you just unscrew the big nut.

    • See 2 previous
    • Rob Rob on Dec 11, 2018

      Thank you Tom for this very thorough answer! Any tips about how to make sure I keep the blade even and balanced? I imagine if I get that wrong it's bad news!

  • Seth Seth on Dec 04, 2018


    To remove the blade, you need to keep it from spinning while you loosen it as you cannot hold the blade and untighten it at the same time. The easiest way to do that is to take a length of 2x4 ( I've even used a log before) and wedge it between the blade and side of the housing. Now, when you loosen the blade, it will catch on the wood and provide the resistance you need to loosen the nut. You may need to apply a considerable amount of force if it was over-tightened when it was installed or has rusted. Remember to drain your gas tank or clamp the line from the tank to the mower. Every mower is different, but you generally never tip it towards the spark plug and do tip it so the oil fill tube is facing down. Check your owner's manual for how you would change the oil and tip it the same way to remove the blade.

  • JoeStatenIsland JoeStatenIsland on Dec 05, 2018

    A lot of good advice in all of the previous answers so I won’t reiterate. The only comment I would add is probably the most critical! You MUST make sure that you balance the blade before you re-attach it to your lawn mower. A simply way to do this is to support the blade at the point precisely in the center of the bolt hole. The blade should remain balanced in a horizontal position not falling to the left or right (sort of like two equal weight children on a teeter-totter). If not, proceed to sharpen the heavier side a bit more until it balances. Balancing the blade is a very important step. An unbalanced blade will cause the lawn mover to “rock-‘n-roll” when running and will eventually wear out the shaft into the engine. Good luck! ...JoeStatenIsland

    • See 1 previous
    • JoeStatenIsland JoeStatenIsland on Dec 11, 2018

      I use a triangular piece of wood. I simply sit it on my table and position the center of the blade bolt hole over the top edge of the block. The last time I did this, I couldn’t find my triangular wooden block that I made so I secured a wooden grade school ruler in my Black&Decker Workmate and balanced the blade on it. The blade only tipped slightly to the left. A few strokes at the sharp end edge of the blade on its left side, and the blade balanced perfectly on the ruler’s edge. This may sound complicated/difficult but it really is not. After you have done this once, you will see how easy it is. Good luck! ...JoeStatenIsland

  • Michael McNinney Michael McNinney on Dec 05, 2018

    Why bother there only $15 or $20. Buy a new one and have the old one sharpened so you can change them out twice a year. Thanks what I do

    • Rob Rob on Dec 11, 2018

      Thanks for the tip Michael, but I always try to do things myself first. I have learned a lot this way over the years. It's less about the money, and more just a way of life!

  • Terri Duplessis Terri Duplessis on Dec 05, 2018

    I did the exact same thing!

    Cheaper than I expected !!

  • Piet02ch Piet02ch on Dec 05, 2018

    Grind both sides with the angle grinder.

    Make sure that both sides are in the balance.

    Just a screwdriver in the middle and see if it is balanced.

    • See 1 previous
    • Piet02ch Piet02ch on Dec 11, 2018

      No, block the knife with a piece of wood, then loosen nut. Fix the knife well in a vice or on a table. Grind both with the angle cutter. Check if it is in the balance. That was.


  • Bob Hoffer Bob Hoffer on Dec 05, 2018

    Remember the first thing you do when removing the blade is disconnect the spark plug , for safety reasons

  • EdMichigan EdMichigan on Dec 05, 2018

    All good advice, but one more very important step, make sure you disconnect the spark plug prior to manipulating the blade because there is a remote chance you could accidently start the mower.

    • See 1 previous
    • Seth Seth on Dec 11, 2018

      It won't be able to start, but it's possible there is some residual compression in the engine cylinder that would cause it to spin a little. Before you loosen the blade, give it a spin by hand. Turn it clockwise to the right as you look at it from the bottom.

  • John Biermacher John Biermacher on Dec 05, 2018

    Lot's of good advice, but I will add my two cents.

    1) They make a tool that safety locks your blade in place when you loosen/tighten the retaining nut. They are less than $10 and make a great gift for a gift exchange. Purchased mine at Menards but this link shows they are also available at Home Depot.

    2) Make sure to use a socket of the correct size to remove/tighten the nut. An adjustable wrench will likely round over the corners.

    • See 1 previous
    • John Biermacher John Biermacher on Dec 11, 2018

      Rob, You may get by with an adjustable wrench, but the nut is usually difficult to remove and you end up rounding off the edges.

  • Joy30150932 Joy30150932 on Dec 05, 2018

    If you decide to remove the blade yourself be sure to mark which way it goes on the mower or you could end up putting it on backwards. Most of the other advice is good.

  • Tom Tom on Dec 05, 2018

    I've used knife sharpeners and also a Dremel type tool with a grind stone.

    • See 1 previous
    • Tom Tom on Dec 11, 2018

      The knife sharpener was easier and faster. The one that I've used is about 6" long has a white body w/a blue handle. Great for knives too. I did see something like it at ACE Hardware.

  • Betty Betty on Dec 05, 2018

    Hi you got some great answers. .I enjoyed John answers looked up the House depot gadget would make a nice Christmas gift for my husband. .I am still not sure if it will work on 52 inch deck. We have a zero turn . I had to switch from John Deere to Toro to get the steering wheel. .my other one was really hurting my shoulder and arm. .wanted power steering. .ha .Merry Christmas .

  • Barbara Barbara on Dec 05, 2018

    It usually only costs about $7 to $9 dollars to have a blade sharpened at a mower shop. I also keep two blades. When one needs to be sharpened it goes to the shop; the other goes on the mower. A lot easier than going thru the trouble of sharpening them yourself, unless you have a 'handyman' that will do it for you.

  • Paul Eaton Paul Eaton on Dec 06, 2018

    A perfect balance of the blade is a must. Even the slightest unbalance can cause undue wear on the engine bearings resulting in a shorter life span of the mower. I suggest taking your blade to a mower shop and getting it done right or buy a new one at most DIY outlets.

    Hope this helps,


  • Ellis Ellis on Dec 06, 2018

    The solution, as others have said, is to buy an extra blade and swap them out. Have the dull one professionally sharpened, it's way better than trying to do it yourself, and it's not that expensive.

  • Jim Evans Jim Evans on Dec 07, 2018

    I get my wife to do it!

  • Joy30150932 Joy30150932 on Dec 11, 2018

    Hilarious, Jim

  • Marcia Marcia on Dec 15, 2018

    I was never able to get there blade off my electric one so I use a diamond dust finger nail file to run over the edge.