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How to remove a lawnmower blade

With the fine weather lately, your joy knows no bounds watching the flowers blossom in your garden. The grass appears slightly longer, and perhaps a lawnmowing session is needed. You bring your tried and tested lawnmower out to give your grass an excellent, neat cut. But wait, why is the mower leaving patches of uncut grass? You happen to know instinctively that the problem lies with the blades that might have become blunt with time. But you don’t want to take the mower to a mechanic who might charge you extra bucks for a replacement. You’re a DIY type of guy who’s just looking online for how to replace the lawnmower blades. Well, if that’s the case, then it’s good news for you since we are here to provide you with answers that address your problems related to lawnmowers.

Lawnmower blades are situated at the bottom of your machine. Most powered lawnmowers come with a single set of blades. Some may have a second set working simultaneously. The blades often wear out as their service life gets used up or damaged by stones or other debris. In those cases, if you see that the cutting patterns aren’t uniform, a blade replacement is imminent. Following are the steps that will help you replace your lawnmower blades:

How to remove a lawnmower blade:

  • Inspect the existing set of blades and determine their condition
  • Purchasing the right kind of blades for your equipment
  • Installing new blades with the right method
  • Test the lawnmower with the replaced blades

We shall provide you with in-depth details of these steps, as mentioned above.  Such as what precautions to be mindful of and what equipment to use for such tasks. Stay tuned to this article for this information.

Steps to Replace Lawn Mower Blades:

The procedure below details all the necessary steps to replace the worn-out lawn mower blades with a new set of knives that ensures a regular cutting pattern.

1. Inspection of existing mower blades:

Lawnmower blades usually wear out after 200-300 hours of service, and thus they reach a point where replacement is inevitable to ensure steady operation. Sometimes, the edges might get damaged due to rocks or stones that lie inside the grass of the mowed surface. In these situations, one must inspect the lawnmower blades to understand the extent of damage better. Witnessing gouges or hunks of blade missing means that a replacement is inevitable.

– Step 1: Turn the mower upside down:

The lawnmower blades usually lie underneath the machine. To inspect them, however, you need to tilt the mower upside down. This act requires caution as there is a possibility of fuel leakage occurring from the tank. To counter that, you should close the fuel valve (if available), or you can wrap a plastic bag around your fuel cap. This creative yet straightforward technique can prevent leaks from occurring.

– Step 2: Inspect the blades and disengage the spark plug:

Look out for damaged edges of the blade. Try rotating the blade to check if there is any play or hindrance offered to the rotation. We recommend that you should disconnect your lawnmower’s spark plug as there is a risk that the machine might start due to rotation offered to the blades. This is a situation that you should avoid at all costs.

2. Purchasing a new set of blades:

Now, as you witness the damage that your blades have experienced, you finally make up your mind to get a new set of blades for your lawnmower. While doing so, you should take care that you get a new collection that is identical to the one replaced. For this purpose, always consult your user’s manual to get the machine’s right model number. And while making the purchase, always ask the seller to provide you with the correct blades for your particular model.

3. Installing the blades:

To install the new blades, you should place your lawnmower upside down, ensuring that the fuel cap is sealed and the spark plug disengaged.

– Step 1: Get the right equipment:

To remove the blades, we prefer to use a ratchet spanner to loosen or tighten the bolt that connects the blade to the central disc. If a ratchet spanner isn’t available, you may also use a standard spanner, preferably with a more extended arm, so that it provides you with greater leverage or torque.

– Step 2: Remove the blade:

The bolt needs to be loosened by turning the spanner in an anticlockwise direction. To prevent the edge from rotating while the loosening/tightening of the bolt, we recommend that you should connect a pair of vice grips to the deck of your lawnmower. Or you can place a wooden block between the blade and the drum to prevent the edge from rotating.

– Step 3: Install the new one:

After removing the blades set, place it on the ground in the direction you took it off. This will help you compare the new blades with the removed ones and install them in the right order. Note that the cutting edge has to face upward so that the chopped grass goes upward. (Figure)

– Step 4: Check for play:

Now connect the blade to the disc by aligning all the holes and tightening the bolts. During drawing, the wooden piece or the vice grips need to keep the blade in place by preventing it from rotation. If nothing is available, you can wear gloves and hold the blade in its place with your hand. Tighten the bolt until you fully tighten the set and observe no play.

4. Test the lawnmower with new blades:

Now that you have installed a new set of blades for your machine, why not take it out for a test run. Remove the plastic bag from your gasoline tank and reconnect your spark plug. Now pull the trigger of your engine and mow the grass with the new blades you have got. You will now notice a much smoother cutting pattern with no uncut grassy patches.

For a hands-on demonstration of how to replace and install new blades, you should watch this video:


1. Are lawnmower blades reverse threaded?

Most lawn mowers blades are reversely threaded, which helps them secure on the engine’s driveshaft. The purpose of this is to ensure that the blade’s rotation while the cutting action does not loosen instead of tightening the nut, which connects it to the drive shaft.

Generally, a bolt’s loosening means a right-hand thread in the clockwise direction, while tightening refers to a left-hand thread in anticlockwise order. The blades are reversely threaded in lawnmowers, meaning that loosening is done from the left or clockwise direction. Whereas tightening is done in anticlockwise order. As explained above, this reverse threading makes sure that the rotation of blades tightens them instead of loosening them to ensure their connection with the drive shaft. Most lawnmowers use this mechanism. Some may use other techniques to ensure the safety of the drive shaft as per the required conditions.

2. How do you remove and sharpen lawnmower blades?

Lawnmowers blades often need to be sharpened to ensure their proper functionality. The following are the steps you can follow to sharpen the mower blades.

– Step 1: Removing the blades:

  • Plug the oil cap of your mower with a plastic bag and disengage the spark plug. Now turn your machine upside down so that the blades at the bottom are visible.
  • Secure the blade at one position by placing a piece of wood at the edge. This is done to lock their rotation, which makes the loosening easy.
  • Use a ratchet spanner or a general spanner to loosen the bolt that secures the blade on the drive shaft.

– Step 2: Sharpening the blade:

Now that the blade has come off, you can use a grinding machine (if available) and grind off its cutting edge to sharpen it. You can also use a hand file to do the job if the grinding machine isn’t present.

– Step3: Fixing the blade back:

Now that it has been sharpened, it needs t to be fixed back onto the mower. Make sure the blade’s cutting edges are aligned in the upward direction relative to the base. Or you can take a picture of the blade before disassembly that will help you remember their correct orientation.

You can refer to a video as attached in this URL that explains the entire process:

3. How many times do you need to sharpen a lawnmower’s blades?

Typically, most lawnmower blades need to be sharpened twice a season. Sharp cutting blades help trim the grass evenly, which increases the recovery time of the grass. Moreover, having a sharp cutting set can lower your mower time, thus contributing to overall productivity. If you witness irregular cutting patterns all around your garden, then it might be high time to sharpen your blades. Debris or rocks in the lawn increase the instances of blade maintenance. It is better to sharpen the blades once at the start of the season and somewhere in the middle.

4. Is it OK to wash a lawnmower?

Lawnmowers need to be serviced timely because they accumulate grass and dirt. The grass can lead to the buildup of moisture that can eventually corrode your machine’s metal parts. Hence, it is mandatory to ensure that your lawnmower is cleaned at least twice a cutting season. Most people, though, wash their machines every month, depending on the extent of dirt buildup.

  • Before washing the lawnmower, make sure that the spark plug is not connected. It prevents the machine from accidentally starting.
  • It is safe to use a garden hose to wash the lawnmower. You should not spray water on the side as it can enter the air filter of your engine. Instead, spraying should be from the top.
  • You can also use a bucket full of car wash detergent during the cleaning of your lawnmower. During cleaning, make sure you remove the dried grass chunks from the bottom of the lawnmower. Then clean the underside with soap water.
  • After it has been cleaned and rinsed properly, it should be left to dry for at least an hour.

Final Remarks:

If you’re a garden enthusiast, you’d be obsessed with your lawnmowing as it is satisfying and makes your mood pleasant. Witnessing an evenly cut grass is indeed a cherry on top. For this purpose, we always recommend that you service and maintain your garden equipment well. If the machine behaves unusually, you should investigate the root cause behind that. As in the case of uneven cutting, the root cause was faulty mower blades. Sharpening your knives at the start of every season ensures that they’ll last the entire season. You should also not forget to perform the timely maintenance of your machine parts (mower blades, engine oil, carburetor, filters, etc.) As a golden principle, you should always remember that a machine takes care of you as long as it’s being taken care of.