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Which Side Of The Lawn Mower Blade Is Up?

You are probably wondering how to tell which side of your lawn mower blade is up. We have researched all about lawn mower blades for you.

In order to figure out which side of a lawn mower blade is up, you should be able to recognize what side of the blade is sharp and which side is dull. Whichever side of the blade that is sharp is the edge that does the cutting. The sharpened side faces the ground as to cut the grass successfully, and the dull edge faces the lawn mower’s deck.

Keep reading to learn more about how to determine which size lawn mower blade you will need, which direction your mower blades spin, what happens if you install lawn mower blades upside down, and how to sharpen your mower blades.

Red lawn mower upside down and container full of grass, Which Side Of The Lawn Mower Blade Is Up?

Lawn Mower Blades

Another way to figure out which side of your lawn mower blade is up is to look for a stamp, sticker, or writing etched into the blade. Most blades that are new have a sticker or writing etched into the blade stating which side is down. The two most common phrases etched onto blades are “This Side Down” and “Toward Grass.” Look for one of these phrases to help you understand which side is up.

If you are having difficulty determining which side of the blade is sharp and which side is dull, the ends taper and should point upward.

Lastly, you can always check your manual to help you figure out which side of your lawn mower blade is up. If one of your blades seem damaged with large dents or chips, it is probably time to replace it. Investing in new mower blades will help your lawn mower preform more efficiently.

Types of Mower Blades

2-in-1 blades, which are standard, are made to cut grass in such a way that the aerodynamics cause the cut grass to powerfully eject the clippings out from under the deck of the lawn mower. This happens so that the cut grass does not clump up under the lawn mower causing it to become compacted. Lawn mowers are designed to have the clippings discharge from the side of the deck or to fill an attached removable bag. The removable bag makes disposing of the clippings easier.

The other most common type of lawn mower blade is the “mulching blade.” These are referred to as 3-in-1 blades because they perform a unique action. 3-in-1 mower blades do what standard blades do in addition to a third feature. They can also shred the grass clippings into a desirable fine mulch to be left on the lawn almost unnoticeable.

Mulching blades look different than standard lawn mower blades. The cutting edge of a mulching blade has points on one side. This points should face the sky. If your blade does not already have a sticker or etched words indicating which side is up or which side is down, we suggest you add a sticker and label it.

Mulching your grass is environmentally friendly, but can cause your mower to become clogged under the deck of your lawn mower. This is especially true if the grass you are cutting is overgrown or wet at the time.

How do I know which size lawn mower blade I need?

The three things you want to check when sizing your lawn mower blade are the length, width, and placement of the center hole. The space between the outer holes and thickness are two more essential measurements to note when choosing the right lawn mower blade for your mower. When you measure the length of your existing blade you measure diagonally from one tip of your blade to the tip on the opposite end.

Typically lawn mower blades measure between 16.75 inches and 22 inches. Even if your original lawn mower blade is 18 inches long, the majority of lawn mowers can accommodate 21 inch blades. You do not want to install blades that are smaller or shorter than the original blades.

Which way do mower blades spin?

Characteristically lawn mower blades rotate clockwise if you are thinking of which direction from standing up looking down at the deck. If looked at from underneath, the blades spin counter-clockwise. Checking to see which side of the deck the discharge chute is on is an indication of which way the blades spin and cut.

If the discharge chute is on the right side, the blades turn clockwise. If the discharge chute is on the left, the blades rotate counter-clockwise. They are built this way so that the blades spin in such a way that they help guide the blades of grass to be released out of the chute.

What happens if you install lawn mower blades upside down?

Red lawn mower upside down and container full of grass, Which Side Of The Lawn Mower Blade Is Up?

Theoretically if you were to install your mower blades upside down, they would not cut the grass. If the blades are installed upside down, the sharp edge would be facing the deck of the lawn mower rather than the grass.

This mistake can also damage your lawn mower. It is a potentially dangerous and costly mistake. Refer back to our answer on how to determine which side of your blade is up before the installation process.

How to sharpen lawn mower blades?

After you have figured out which side of your lawn mower blade is the sharp edge, you will know which edge to sharpen. If your blade has become dull before you check, understand that the cutting edge faces the grass, therefore, it will be the side that needs sharpened.

There are several methods for sharpening lawn mower blades. Some lawn mowers are put together in a way that you can sharpen your blades without removing them. It is usually necessary to remove the blades in order to sharpen them. You can do so by using a bench grinder, hand file, rotary tool, or angle grinder.

Some tips and tricks for sharpening your mower blades are to understand that eventually your mower blade will become thin and need replaced, but until then sharpening the blades will make your lawn mower last much longer and preform proficiently. Doing this will help cut down your mowing time. It also helps ensure you will end up with a nice evenly cut lawn.

In order to prevent grass from building up under the deck of your lawn mower, you can spray the underside with non-stick cooking spray or Teflon spray. It is important that blades are tightly secured. With the spark plug wire disconnected, you can attempt to wiggle each blade. If the blade wiggles, it needs to be tightened. A socket wrench should do the trick.

You do not need to sharpen your blade to such a sharp edge that it will cut your hand. Grass is not nearly coarse enough to need your mower blades to be quite this sharp. You do want to be sure to sharpen each blade similarly so that they are balanced when re-attached.

Although a file, rotary tool, and bench grinder will work for sharpening your mower blades, using an angle grinder is the fastest easiest method. Multi-functional sharpening tools are available for purchase as well.

Click Here to see the Sharpal All-in-1 Multi-Sharpener on Amazon

How Often Should I Sharpen My Mower Blades?

A good rule of thumb for deciding when to sharpen your blades is to do this about every 20 to 25 hours of run time. How often you need to sharpen your blades is determined by how often you mow, and how long it takes you to get the job done. You can repeat this process five to ten times or more before needing to replace your blades. High-quality blades last even longer!

In Closing

To determine which side of your lawn mower blade is up, first figure out which side is the sharp cutting edge, and which side is the blunt edge. Look for a sticker indicating which side goes up and which side faces downward. The cutting edge should face the grass while the dull edge should face the deck of the mower.

If you would like to learn more about lawn mowers and sharpening lawn mower blades check out the links below:

How Much Does A Riding Lawn Mower Cost?

Where To Sharpen Lawn Mower Blades?

10 Best Lawn Mowers For Wet Grass

Sunday 26th of June 2022

Thanks for posting this, sometimes it doesn't occur to clients that there is a wrong way to install a mower blade!