How to Straighten and Sharpen a Lawnmower Blade





Introduction: How to Straighten and Sharpen a Lawnmower Blade

Bending lawnmower blade is never fun and can be very frustrating. If you're ever unfortunate enough to bend one I hope this helps you fix it.
So here's how I did it I took me about ten minutes to do this repair.

Remember if you do this, the blade can break,so be careful and you your best judgement. At some point you will need to replace the blade, for me this point was after the fourth time Istraightened it

Step 1: Tools

For this repair I used:
Ratchet with long handle A socket the size of the bolt on my mower

A pair a Channel lock pliers (any large pair on pliers will work)

Shop rag

Ball peen hammer

Sledge hammer File

Work gloves

And an anvil of you have one

Step 2:

Flip the mower up on one side it's better to flip the mower so that the air filter is up so that gas or oil does not drain in to the air filter.
Take the socket and wrench and remove the blade you will need something to brace the blade against, I usually do this with my foot. If you don't want to use just your foot for this get a large price of scrap wood and put that between your foot and the lawn mower blade. Once the blade is removed flip it back over so that it sits on the ground like it should.

Step 3: Bend It

The best method I have found for doing this is to place the none bent end under the anvil and use a pair of channel locks to bend the blade back to fairly straight.
If you don't have access to a anvil it would work just as well to put the none bent end in a vise or even clamp it to the work surface with a very strong clamp.

Step 4: Hammer It

Take the ball peen hammer to flatten out the last of the bend I use the avil for this but if you don't have access to one a sledgehammer will do the anvils job.

Step 5: Sharpen It

Grab the file and hold the straightened blade against your work table, use the file to sharpen the cutting edge of the blade, if you are having trouble finding this the cutting edge of the blade is usually the cleanest part of the blade. Put the file up to the blade and apply slight pressure and drag the file away from it. Make sure that all the strokes go away from the edge.
It you happen to have the dremmel and lawnmower sharpening atackment or a bench grinder just use that.

Step 6: Reattach the Blade

Take the straightened blade, wrench and socket, flip the lawnmower up on its side and reattach the lawnmower blade. when you think the lawnmower blade is on tighten it some more , its better to be safe then sorry when dealing with this kind of thing.
if you enjoyed this or found it in anyway helpful please remember to vote for it.

please remember it be careful and use your best judgement.

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    I have a couple of problems with my Honda petrol strimmer and each time I have dropped off the item, It was repaired very quickly at a reasonable cost.

    I also bought a new Honda self propelled petrol mower and they did a price match with major online retailers.
    Plus they assembled the mower for free!!
    Overall I am a very satisfied customer.

    • Very cool. If I was shopping for a new mower I would
      definitely try something like this. I used to have a Black and Decker electric one, but the cord was a pain. Then we got a self-propelled gas mower (I loathe
      it). The one divorce issue that's weighed the most on my mind is not wanting to
      mow the lawn, so I am selling all of that type of equipment and paying a guy to
      mow every other week ;)

    I would like to politely and constructively suggest that anyone who flips their gas lawnmower over and turns the nut holding the blade without first disconnecting the spark plug wire is pretty much begging to be relieved of a finger or two. On many machines just turning the blade 1/4 turn will START THE FREAKING MOWER. Too bad Sk8ty forgot to mention that.

    1 reply

    thank you for mentioning that, i did not realize how easly you could start the mower

    I don't know what kind of blades you people have but the ones on both my push mower and my riding mower are much too hard to bend with a pair of vicegrips. I tried using a 36" pipe wrench and still could not get them to bend back into shape, also beating with a 4# sledge hamer against the anval didn't work eitherl.

    1 reply

    im sorry that this method did not work for you, you could try heating the blade up before you try to straighten it.

    if the blade is that tough how did it become bent?

    Straightening a bend such as this on a mower blade is extremely dangerous. There is a substantial possibility of creating an undetectable fatigue crack in the metal allowing the blade to fly apart due to centrifugal force. Magnafluxing is the only way to detect such a flaw and it is not practical for such a low value part.

    Your grass is like Chuck Norris. I don't think I've ever bent a blade!

    1 reply

    no unfortunately my grass is not Chuck Norris, I bet the blade on a 2" piece of steal pipe that got from a fence repair

    Having done this more than a few times as a groundskeeper, a real quick way to do this is to clamp the blade in a vice, hammer the edge back into shape, then sharpen using an angle grinder.

    I did this pretty much every day for 4 months straight, never had a blade fail!
    Also, keep in mind that a blade should generally be sharpened every 8 hours of use.

    Good write-up, by the way!

    1 reply

    thanks for the writing complement

    I would have used a vice if I had one, and the same thing with a grinder, I found that by bending the blade mostly straight before hammering it, that I did not damage the end as much.

    Nice write-up , I've bent a few blades before. One thing to note - if you tilt the lawn mower the wrong way , sometimes fuel or even oil gets on the spark plug and makes it hard to start. If that happens, pull the plug and use a wire brush to clean the electrode.

    1 reply

    thanks for the suggesting where the spark plug is on my mower I have not had a problem with that.

    Ok thanks for the suggestions I have not hade a problem with the blade being out of balance but I have had problems with getting the tilt right and having it toss the cut grass into the bag

    An extra step you might include is checking the balance of the blade. Put a round screwdriver in the center hole and see if it balances. If one side keeps going down you should file it down a little until it will sit evenly. If the blade gets to far out of balance it will vibrate like crazy and destroy the crankshaft bearing. Sometimes when it hits something like a rock it will chip off a little bit of metal and that is why you should check it.

    I have had trouble getting some of the mulching blades to straighten correctly. They have a twisted blade to start with and getting it back that way is a problem.

    A piece of railroad rail makes a great anvil. A foot long section is about right. It weighs a lot and you can pound on it all day and not bother it.