How to Sharpen Lawn Mower Blades (Solved!)

Mowing the lawn is a fun task that many people enjoy. However, if your blades are dull and you’re not using them correctly then it can be hard work. If you want to make cutting your grass enjoyable again, read these tips on how to sharpen lawn mower blades.

How to Sharpen Lawn Mower Blades with a File

Considering the fact that files make a lot of metal fragments called swarf, you’re going to want to put on gloves before you try out these following steps:

  1. Disconnect power to the lawnmower
  2. Safely detach the blades
  3. Clean the blade free of any excess debris left over from cutting lawns
  4. Using a vice grip, mount the blade assembly with the business end up
  5. Take a fine file and gently work the edges of the blades
  6. Find the bevel on the side of the cutting end and rub over it in a circular motion
  7. Run the file in a single direction all the way along both sides of the bevel until it’s sharped
  8. Take the blade out of the vice grip
  9. Carefully remove any material from the cutting surface
  10. Re-attach the cutter and make sure the bolts are nice and tight

Using a file to sharpen the blades of a lawnmower is a lot like using a whetstone in reverse. You’ll want to find the right angle of attack and keep at it until the blade is honed down to an edge.

How to Sharpen Lawn Mower Blades with a Grinder

Using a grinder is much different than a file. First, you’ll want to disconnect the power and remove the blades before trying these steps:

  1. Position the blade upwards in a third hand device like a vice
  2. Power up a hand grinder with a fine head
  3. Run long, even strokes along the edges of the blade with the grinder
  4. Find the angle of attack by leaning the grinder slightly in or out so you don’t dull the blade
  5. Make longer passes over each side of the blade’s bevel once you found the right pattern
  6. Gently test the edge of the blade to judge its sharpness
  7. Continue to grind the cutting side until it feels balanced
  8. Use even pressure to reduce the risk that you dull the blade in the process
  9. Wipe the blade once it’s done
  10. Reattach it securely before use

Due to the fact that it’s powered, a grinder should take much less time to sharpen your blades than a file would. Take care, though, because it’s also easy to damage them this way.

Can You Sharpen a Lawn Mower Blade Without Removing It?

While it’s difficult to sharpen a lawnmower blade without taking it off, you might have to if it’s stuck and there’s no way to get it loose. If that’s the case, then you’re going to want to completely disconnect all power sources before you try anything.

Pull the spark plug cap if you’re working with a gas-powered mower. Take a 10″ mill file and then use good long strokes with the file along the outside bevel of the blades.

Get all sides of the blade if possible. Most 10″ files will give you enough leverage to get underneath the other side of the blade and sharpen it.

What Is the Proper Angle to Use?

Manufacturers usually tell you the proper angle to sharpen your blades at. It all depends on how they were cut and ground to begin with.

Assuming you no longer have the manual for your lawnmower and can’t find the information online, you might be able to find the angle by leaning a file against it. Take a few swipes and lean it in toward the blade so you can find what angle feels the best.

Though there are devices designed to help DIYers find the right angle to sharpen a blade at, these may not work with lawnmower cutters because they’re generally designed for knives.

How Sharp Should Lawn Mower Blades Be?

Tall grass demands sharp blades to really power through it. The best way to tell if your blades aren’t sharp enough is to check how they deal with the tallest parts of your lawn.

Chances are that if they’re starting to clog or pull up the grass as opposed to actually cutting through it, they’re not sharp enough to deal with the type of lawn you’re cutting. Usually, though, a blade that was sharpened at the beginning of a summer season should last all the way through if you’re not doing heavy landscaping.

How Often Should Lawn Mower Blades be Sharpened?

Assuming you live in an area where the lawn doesn’t have to be cut at all times of the year, start the season by cleaning and sharpening the blades of your lawnmower. Many people find that if they do, they can go an entire season without having to hone them again.

Push lawnmowers that don’t have any source of external power generally need to be sharpened more often than those that run on gas or batteries. You’ll also want to make sure that the blades for these are balanced to encourage even wear.

Do You Sharpen Both Sides of a Lawn Mower Blade?

Modern beveled lawnmower cuts are often designed to be sharpened on both sides, but this isn’t universal. If they’re meant to be, then you’ll see the kind of cut edge you’d find on a kitchen knife extending over both sides of the blade.

Cutters that are only supposed to be sharpened on a single side will literally only have one bevel if any at all. This will normally point down and the other side of the blade’s edge will simply be a flat plane in that case.

Does Ace Hardware Sharpen Lawn Mower Blades?

Ace Hardware locations are independently owned and operated, which means that their individual managers have a high degree of autonomy to decide what services their stores have. Many retail locations do sharpen lawn mower blades for a small fee, so you’re encouraged to call for details.

Some Ace Hardware stores will sharpen other lawn tools in addition to mower blades as well. Most locations have a list of all of the services they offer inside.