If you’re aiming for a longer lifespan for your lawn mower, it’s a no-brainer that keeping its blades sharp and well-maintained is crucial. Yet, not all mower blades are the same in terms of their mechanics. It’s easy to get puzzled, especially if you’re new to this.
Luckily, as someone who’s been involved in lawn care, I can clarify the mystery surrounding why certain lawn mower blades are reverse threaded and how they operate.
Are Lawn Mower Blade Nuts Reverse Threaded?
Before we begin, it’s important to clarify that “reverse threaded” doesn’t pertain to the mower blade itself. It’s actually about how the lawnmower blade nut secures the drive shaft.
Here’s the deal: Is the blade moving counterclockwise against the typical cutting direction? If that’s true, you’re looking at a reverse-threaded nut. This threading type ensures that the blade’s rotation doesn’t inadvertently loosen the blade retaining bolt on the drive shaft.
Sounds good so far, right? But here’s an interesting tidbit: Not all lawnmower blade nuts are reverse threaded. In fact, if you look at today’s market, you’ll observe that most lawnmower blades use a right-hand thread, which means they rotate in a clockwise direction.
Of course, this can vary from brand to brand, as I’ll briefly touch on below.
How Do Lawn Mower Blades Work?
When working with gardening and landscaping tools, cutting blades are essential for the performance of a lawnmower. 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.
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 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 I 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.
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. So, I carefully 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.
You can tighten the nut by turning it in a counterclockwise direction and turning it right when removing mower blades. I urge 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 I 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.
It’s a mandatory process to prevent undesirable accidents due to sudden start-ups. Besides that, I also suggest 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 me when I 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.
It is recommended to use 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.
Read Next: Do You Need to Sharpen New Lawn Mower Blades?
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 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, trust me when I say that learning to how to handle these things single-handedly will make your lawn mowing journey more convenient and efficient.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
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