sharpen mower blade

You’ve been meaning to take care of it for a long time now, but you just…keep..putting it off.

I’m talking about sharpening the blade on your lawnmower.

But you can’t hide from the facts any longer: The blade on your lawn mower is dull. While this may seem like a small issue, it can cause big problems if left unattended. A sharp lawn mower blade cuts clean and helps grass plants recover quickly which reduces the time you spend mowing the lawn.

In this article we will show you how to sharpen a lawnmower blade so that you can have that perfect green yard all year long!

What are lawn mower blades and why do they need to be sharpened?

The blade on a lawn mower is the piece of metal that makes contact with and cuts the grass. A sharp blade can cut the grass cleaner, which is what gives your lawn that nice, even appearance. As you use your lawnmower to cut your lawn over time, the edge will become blunt and less effective at cutting cleanly. Dull blades can lead to an uneven or patchy looking yard.

You don’t have to sharpen your blade – it’s perfectly acceptable to go purchase a new replacement lawn mower blade and just be done with it. But if you believe it’s best to reuse before recycle, the following instructions are for you.

How often should you sharpen lawn mower blades?

A lawn mower blade should be sharpened every two months, or twice each season. You can do it yourself with tools you likely have lying around the house. If you decide you’d rather purchase a new blade instead of sharpening the old, be sure you are buying the right size blades for your make and model. You can bring the old blade with you to the store to help as a guide.

What tools do I need to sharpen the cutting edge on my lawnmower blades?

You’ll need a few tools that you may already have in your garage or shed. These include:

  • A can of spray lubricant (typically WD 40)
  • Rags
  • Gloves
  • A socket or ratchet wrench
  • A Mill bastard file if you are using a hand file – or a bench grinder / angle grinder if you feel confident with those tools. These instructions assume you are using a hand file.
  • A 2X4 wood block to help remove/install the mower blade.
file for sharpening a blade

How do I sharpen my lawnmower blade?

Sharpening your lawnmower blade edge isn’t a very complicated process. It’s also not very dangerous as long as you follow some basic safety rules. The main rule: DON’T TURN OVER A LAWNMOWER THAT MIGHT BE ABLE TO START – PERIOD!

  • (If using a gas lawnmower) – empty the gas tank and disconnect the spark plug wire. If you are really safety-conscious remove the spark plug from the mower.
  • (If battery-powered) – remove the battery from the lawn mower.
  • Remove the blade from the lawnmower. You can remove the blade from your lawn mower by removing one or two nuts on the underside of the mower deck. These are usually found in the middle of the mower and require a wrench to loosen.
  • Once you have removed the bolt(s), take off any washers that may be present in order to pull out your old blade.
  • Put on protective gloves and eye protection before sharpening the blade. While your blade might be generally dull, now is not the time to discover with you hands just where the sharp parts are located.
  • Use a file to sharpen the blade. Place the mower blade in a vice so it won’t move around on you. Move your file in the direction of the original cutting angle, sharpen the cutting edge on the blade. A rule of thumb is to file until the blade is as sharp as a butter knife – we don’t need the cutting edges to be razor sharp to make grass clippings!
  • Repeat the sharpening motion on the other side of the blade 
  • Use a blade balancer (or a simple string tied to the center hole) to make sure the blade balance is true. If one side of the mower blade hangs significantly down, sharpen the blade on that side to remove some steel to bring it back into balance.
  • Put away your protective gear and place your lawnmower blade back onto the deck. Tighten the nut tightly.
  • Congrats – You’ve finished your first lawn mower blade sharpening with flying colors!

What are the benefits of sharpening your lawn mower blade?

  • You’ll get a nicer cut and therefore healthier grass with a sharper cutting edge.
  • Your lawn will require less time to mow if you choose to sharpen mower blades regularly, so it’s easier on the environment in terms of emissions from gas/electricity generators as well as noise pollution.
  • A sharp blade can increase fuel efficiency by up to 30% because there is less resistance when cutting through thick grass (or weeds). This saves money on both fuel consumption and engine wear and tear over the course of the season. It’ll also save you time. Not only that but with a sharper blade, you’ll be able to cut a wider swath of grass in one pass while avoiding any scalping or damage to the lawn.
  • Sharper blades last longer; they are more efficient at cutting through high levels of growth without being damaged or needing replacement sooner than necessary.

5. What are some tips for keeping your blades sharper longer?

While time and use always take their toll on the edges of your lawnmower blades, there are steps you can take to keep your mower blades sharper for longer:

  • Maintain the correct blade height. Blades wear out much quicker when they contact hard objects such as concrete or stone which generally happens when your deck is too low.
  • Sharpen the blade after every 25 hours of use to avoid it taking too much time in between sharpening (this may differ depending on usage – again the rule of thumb is no less than every two months during the mowing season).
  • Don’t forget about the mowing deck – these should also be regularly cleaned and maintained so they don’t get rusty from wet grass blades and clippings, which will eventually leave streaks in your lawn’s appearance.

It’s easy to forget about your lawn mower blade, but with a little time and attention, you can be sure that the blades are sharpened regularly so they don’t get too dull. If you have any questions or ways to improve this process please add them in the comments below!

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