Are Lawn Mower Blades Reverse Threaded?

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If you want a functioning lawn mower to last longer, sharpening and maintaining its blades is a no-brainer. However, not all blades work the same. While you can always check if the blade bolt operates in a reverse thread, newbies may find this confusing. 

Fortunately, our lawn care experts can explain why lawn mower blades are reverse threaded and how they work. 

Are Lawn Mower Blade Nuts Reverse Threaded?

Speaking from our team’s extensive experience, we’d like to point out that the term “reverse threaded” isn’t really directed to the mower blade. Technically, it’s a question of how the lawnmower blade nut holds the drive shaft in place. 

mower blade replacement

Does the blade move in a counter-clockwise direction or the normal cutting rotation? If it’s the former, you’re dealing with a reverse threaded nut. It means the blade’s rotation tightens in the opposite direction and prevents the blade retaining bolt from getting loose in the drive shaft.

It may sound great, but did you know that most lawnmower blade nuts aren’t reverse threaded? If you check today’s market, you’ll notice that the majority of the lawnmower blades work in a right-hand thread or a clockwise direction. However, it may vary per brand, which our team will discuss briefly below. 

How Do Lawn Mower Blades Work?

No matter what gardening or landscaping tool you have, it’s not a secret that cutting blades often determine how your lawnmower will work. In order to cut grass neatly, the internal combustion engine must be incorporated appropriately into the mower deck. 

The direction in which the blade rotates is called threading, and this method is crucial for most blades attached to usual lawn mowers in the market. Such rotating objects ensure that the blade remains attached to the frame. It turns the center of the mower blade in the opposite cutting rotation. Because of this, most lawn mower blades have a securing nut. 

lawn mower blades on wooden surface

The way lawnmower blades operate also varies between loosening and tightening methods. Loosening refers to the standard bolt rotation or clockwise direction, and it’s commonly called the right-hand threading. 

On the other hand, tightening happens when mower blades reverse in motion or go in a counterclockwise direction. You may not know, but it’s also referred to as a left-hand thread. 

How to Find Out if a Lawn Mower Blade Is Reverse Threaded

You can spot a reverse thread nut by checking which direction the mower blade starts threading. It may be hard to tell by just glancing, so we recommend using a socket wrench to get the bolt loose. 

If the wrench handle turns right when removing the bolt holding the blade, you have a reverse thread situation at hand. Besides that, you can also verify reverse thread blades through the discharge chute position. If it’s angled on the right side, that particular lawn mower isn’t reverse threaded. 

removing a lawn mower blade

But if you ask our experts, the best way to determine if your mower blade has reverse threads is still by reading through its user manual. As you may already know, not all mower manufacturers use the same kind of bolt head. Because of that, we reviewed each brand and how their blade’s retaining bolt operates. 

Lawn Mower Blades By Brand

John Deere Lawn Mower Blades

The bolt holding the John Deere Lawn Mower blade doesn’t turn in a reverse thread. If you want to tighten its blade, all you need to do is twist it clockwise. For removal, turn the bolt in the opposite direction. 

Craftsman Lawn Mower Blades

The lock nut that holds the Craftsman Lawn Mower blade to its frame is reverse threaded. It includes a threaded hex-headed bolt, and it keeps the blade adapter fitted in the driveshaft. 

craftsman lawn mower blade

You can tighten the nut by turning it in a counterclockwise direction and turning it right when removing mower blades. Our resident lawn care team urges you to follow the Craftsman mower manual for the recommended torque value for well-guided blade maintenance.

Troy Bilt Lawn Mower Blades

Unlike Craftsman, Troy Bilt Lawn Mower blade does not work in a reverse thread manner. The mower’s bolts rotate in the standard direction with right-handed threading. If you want to fasten it securely, it must be tightened from 70 to 90-foot pounds. 

Cub Cadet Lawn Mower Blades

Cub Cadet lawn mowers such as the Cub Cadet XT1 riding mower are not equipped with reverse thread bolts. Instead, these award-winning garden tools [1] threads right-handedly. If you inspect it closer as our experts did, you’ll notice that it includes bolts with ⅝-inch thread that requires tightness up to 90 foot-pounds torque levels. 

How to Remove Blades Safely in 5 Steps

Step #1: Disconnect the Mower from Power

Disconnecting the ignition wire and the spark plug is a step you can’t skip if you’re replacing or sharpening an old blade. If you’re handling a cordless cutting tool, it’s best to remove the battery pack as well. 

disengaging lawn mower blades

It’s a mandatory process to prevent undesirable accidents due to sudden start-ups. Besides that, our team also suggests draining the gas tank. 

Step #2: Retain the Blade

When you flip the mower deck, ensure that the engine air cleaner and tank face upward to avoid any spillage on the air filter. After it’s in place, use a retainer to prevent the mower from moving when you loosen the bolts.

Step #3: Remember the Blade Position

Setting up mower blades, reverse thread or not, isn’t an easy task. So to avoid confusion, take note of which side of the blade is facing downward before doing anything else. 

Step #4: Loosen the Nut

You can trust our lawnmower experts when we say that using very little force won’t be effective when trying to loosen the blade’s nut. However, applying more force may lead to hurting your hand. If all else didn’t work, use a breaker bar for extra help. 

We recommend using a 16mm socket for easier access when doing this process. But keep in mind that the size of the socket ultimately depends on the lawnmower’s model. Most mower blades often come with ⅝-inch or ½-inch bolt heads. 

Step #5: Attach the Replacement Blade

After you sharpened the mower blade or got the replacement, ensure that it fits the adapters. Think back at the previous placement to guarantee that the blade is facing on the right side. Once you turn the bolts back at the correct torque values recommended in the manual, clean the debris under the mowing deck for a smoother cutting operation. 

FAQ

How secure should a lawnmower blade be tightened?

Typically, the zero-turn lawnmower’s blade should be tight and secure enough to prevent it from moving independently to avoid any untoward zero-turn radius mower accidents. The torque values highly depend on the type of blade equipped in your mower. You can always consult the specific unit’s manual for a more accurate specification.

Conclusion

Now that you’re well-informed on why are lawn mower blades reverse threaded, maintaining your cutting tool won’t be too overwhelming. Troubleshooting mower issues may seem hard at first, but our team assures you that learning to handle these things single-handedly will make your lawn mowing journey more convenient and efficient. 

Robert Johnson is a woodworker who takes joy in sharing his passion for creating to the rest of the world. His brainchild, Sawinery, allowed him to do so as well as connect with other craftsmen. He has since built an enviable workshop for himself and an equally impressive online accomplishment: an extensive resource site serving old timers and novices alike.
Robert Johnson

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