How to Sharpen Lawn Mower Blades

How to Sharpen Lawn Mower Blades

Some time ago I was in a hardware store and an associate told me I should bring in my mower blades to have them sharpened as they “had a machine to make them razor-sharp.” I remember thinking, “Why would I want them to be razor-sharp? It’s a lawn mower for crying out loud. I’m not shaving with it. I am essentially trying to achieve the same look on my lawn as a pair of goats could do.

So, here’s a quick article to show you how to sharpen your lawn mower blades to a reasonable honing. Considering you are cutting a plant which rabbits nibble, your 6.5+ HP engine with blades spinning at 3,600 RPM is probably on the side of overkill.

How to Sharpen Lawn Mower Blades

There is one rule I always follow when dealing with sharpening blades of any type: Leather Gloves, Always! Whether you are using this technique on mower blades or a machete, put on a pair of heavy-duty leather gloves or some other kind of protection.

Tools You’ll Need

Mower Blade Tools

The tools you need. A metal file, leather gloves, and a vice.

  • Leather Gloves
  • Metal Flat File or Bench Grinder
  • Socket Wrench
  • Hammer\Mallet\Wood block
  • Bench Vice

Step 1: Turn the mower upside down and take the blade off

Some folks will tell you that turning the mower upside down is bad, as the oil will go to places it is not supposed to. I usually do this at the beginning of the season and my oil has already been drained. However, I have done this before with oil in the engine and as long as I let it sit upright and settle for a while, there have been no issues.

Use the socket wrench and appropriate socket to get the work done.

Hint: The bolt is screwed in like normal (righty-tighty, lefty-loosey), but since the blade also spins it can be a pain to loosen. I find it helpful to use a block of wood or hammer to hit against the blade while I hold the socket wrench (gloved of course), rather than trying to torque down on the wrench and a potentially sharp blade.

Underside of Mower

Turn the mower upside down, preferably after you have drained last years oil and gas. Remove the blade with a socket wrench.

Old Mower Blade

This mower blade is pretty bad off.

Step 2: Place the blade in a vice and sharpen with a file

I have two types of blades for my different mowers: one is a mulching blade (with the extra curve) and the other is a regular blade. The process for sharpening either blade-type is the same.

Run the metal file across the blade and away from you, at an angle, filing on the forward stroke as in the video and pictures shown below.

Note: If using a bench grinder, be careful how much metal you remove (See the next step on leveling). It can be easy to try to remove any imperfections in the blade which may remove more metal than necessary. This is fine as long as you keep both sides the same weight.

Filing a Mower Blade Part 1

Run the file across the blade at an angle and away from you. Place pressure on the file on the forward stroke.

Filing a Mower Blade Part 2

The angle of the file can be determined by the existing edge of the mower blade. Only one side needs to be sharpened.

Step 3: Repeat on the other side and check the balance

While I don’t believe your blade has to be razor-sharp to get the job done, it does need to be balanced. An unbalanced blade will lead to unwanted vibration and noise as well as increasing overall engine\mechanical wear. If you don’t have a handy tool for checking the level of your blade, just rest the blade across your finger, like checking the balance of a good knife. If you have severe leaning on one side, you will need to take off more metal, which means more filing.

Checking Mower Blade Levelness

Check the mower blade for levelness by using a tool which you can pick up at any hardware store in the mower section.

Step 4: Reattach the blade

Put the blade back on the mower the same way it came off. The concave side of the blade faces the grass. Be sure not to over tighten the bolt; you’ll have to do this again next year!

Happy Spring!

– Yarbrough

Related Posts

Gender Non-Conforming Pronouns? // Truck Talk Thursday
Gender Non-Conforming Pronouns? // Truck Talk Thursday
There has been a movement recently to introduce, through legal channels, new gender non-conforming pronouns and to requi
Read More
How Does a Man Handle Sacrificing for Others? // Ask a Man // The Wolf & Iron Podcast
How Does a Man Handle Sacrificing for Others? // Ask a Man // The Wolf & Iron Podcast
When family comes first, how does a man deal with postponing his passions and dreams, sometimes for years? And, are ther
Read More
You are Becoming a Better Man Faster than You Think - Truck Talk Thursday #016 - The Wolf & Iron Podcast
You are Becoming a Better Man Faster than You Think - Truck Talk Thursday #016 - The Wolf & Iron Podcast
Often, when we consider the man we are or our place in life in light of where we want to be, the journey to the other si
Read More
Older Post
Newer Post
Close (esc)


Use this popup to embed a mailing list sign up form. Alternatively use it as a simple call to action with a link to a product or a page.

Age verification

By clicking enter you are verifying that you are old enough to consume alcohol.


Shopping Cart

Your cart is currently empty.
Shop now
Liquid error: Could not find asset snippets/gem-app-footer-scripts.liquid