how to align mower blades

How To Align Mower Blades

Cutting the lawn may be a mere chore for most of us, but even so, it is important that our equipment is in mint condition. Lawn mower blades come perfectly aligned when the machine is new; however over time, this mower blade orientation can misalign; so let’s look at how to align mower blades.

A big problem with lawn mowers is that they do require a lot of maintenance. One of the most important things is that the correct lawn mower blade position is always maintained. If it isn’t, you may find that the lawn mower doesn’t give as clean and accurate a cut as it did when it was new. It might even cause the mower cord to be too hard to pull. However, a lot of homeowners purchase lawn mowers without being aware of this key part of their care.

Before you begin, it is important to determine whether the decrease in the mower performance is as a result of misaligned blades or whether there is another problem. Sometimes, this could be because of too low an engine speed, the deck being too close to the ground; in a 3 blade mower, deck blade position is imperative to achieve a good cut. Furthermore, the issue could be a result of something as simple as a dirty spark plug or fuel filter, cleaning this could solve the issue. But let’s assume that the lawn mower blade alignment is the problem, you will need to take the following steps.

1. Start Safe

Before you do any work, make sure that you have made safety your main priority. You will need a pair of thick work gloves to avoid getting cut. What’s more, it is vital that you switch off the engine and remove the key as well as disconnecting the spark plugs this will ensure that there is no chance of an accidental start-up.

2. Prepare The Blades

Once you are certain that the blades are the issue, you are ready to start aligning them. The first step is to get them into the correct position. To do this, you will need to remove the deck; this will involve removing the safety pins and washers that hold everything in place and sliding the deck out.

You should now be able to turn the mower blades and you will need to have one facing forward and one facing towards the back of the machine. Once they are in place, take a block of wood and wedge this next to the blade that you intend to align. Make sure that it is a tight fit.

3. Aligning The Blade

For the purposes of this article, we will be looking at two-blade lawn mowers in our step by step guide, but if you use 3-blade lawn mowers, we will look at this later on.

You will notice that there is an alignment pin on the blade and this will need to be removed. Put it to one side for later. You can now remove the block of wood you inserted earlier and begin turning the blade until it is perpendicular to the other blade. Once you are happy with its position, you can return the alignment pin and begin tightening the blade screw and other components. If you want to make sure that the blade does not come out of its new position as you tighten everything, you can reinsert the block of wood to prevent this.

4. Putting The Mower Back Together

Once the blade is secured, you will need to replace the cutting deck. This will involve replacing the deck belt around the engine pulley. Some owners may not be confident in doing this. If you feel at all unsure about completing this kind of mower blade alignment then it is a wise idea to take your mower in for repair.

When the job is done, you can avoid future problems by ensuring that you mow in different lines for each pass.

Should Lawn Mower Blades Be Parallel?

When it comes to synchronising lawn mower blades, you will, of course, need to know the best position for the blades to be in. The blades will need to be parallel to one another as when one blade points downwards, this can mean that it will penetrate the soil and damage the ground as opposed to cutting the lawn, as intended.

But this is not the only benefit to having your blades in a parallel orientation. Just consider the following points.

  • Parallel blades ensure a much more precise cut for your lawn.
  • If the blades are not in the correct position, they will not only damage the ground and soil but could also become damaged themselves, meaning that a replacement is necessary.
  • When the blades are properly positioned, the mowing experience will be much smoother and the mower easier to handle.

With all of that in mind, there are mower models whose blades are set in opposite directions and this will be determined by the manufacturer. You should always align your blades in accordance with this to get the best performance.

Blade Mower Orientation

If you own a lawn mower that has three blades then it is important to be aware of the correct 3 blade mower orientation. While this setup may look different to a two-blade mower, the importance of correct alignment is just as heavy.

In most cases, a 3 blade lawn mower will have blades that spin in a clockwise direction, however, this is not always the case. In order to tell which way the blades spin on your machine, you need only look at which side the chute appears on. If this is on the left side, then your mower blades will spin in an anti-clockwise direction. In contrast, chutes that are on the right mean that the blades turn in a clockwise direction.

When you are installing new blades on your mower, it is vital that you put them in correctly so that they will spin in the direction that is intended for that particular piece of equipment. If they are not installed in the right way, this means that the clippings and debris will not be forced out of the chute but rather in the opposite direction. As a result of this, the mower deck will become clogged and the overall performance will eventually come to a slow halt.

In some cases, even when the blades are installed correctly, they may lose their original position. This will result in one side of the cutting deck, or the centre point not cutting as expected and it is important to realign the blades to restore full function.

Blade Position On Two Blade Mower

Two blade mowers are probably the most common type so it is important that we look at the correct blade position for these. When you are installing a new set of blades, there lies the question of whether the blades should cross the middle of the cutting deck at the same time, or whether this should happen at separate times.

In truth, it doesn’t really matter too much unless you are using a timed deck. Having said that, most experienced gardeners would agree that placing the blades at 90º gives a favourable result.

However, if you are using a timed deck, then it is important to place the blades perpendicular to one another. If you do not, then this will result in them colliding during the cutting process and will only serve to damage them, often beyond repair.

It is also important to keep in mind that the blade on the discharge side of the mower tends to wear a lot more quickly than the other. If you regularly take the blades out to sharpen or clean them, then it might be a good idea to swap them over so that they each receive equal wear and have a similar lifespan.

Do Lawn Mower Blades Need To Be Timed?

For the most part, a domestic lawn mower does not need timed blades. This is because this requirement is only for blades that overlap one another during cutting. Normal domestic lawn mowers do not have this feature. Overlapping blades is normally something that you would see on a tractor mower or a zero-turn model.

Mowers with overlapping blades tend to give a much cleaner cut as there are no gaps. However, while they may be useful, when they go wrong, it can be something of a considerable problem. When you install timed blades you should make sure that they are facing in opposite directions. If they are thrown out of place by hitting an obstruction such as a stone, it can often cause a lot of damage to the mower and be pricy to repair.


The correct lawn mower blade alignment is important for several reasons; if the blades are timed, they need to be positioned so that they don’t hit one another. Furthermore, having the correct alignment means that you get a more precise and clean cut.

Further Reading:

Andrew Fisher

Andrew Fisher

Andrew is a dedicated father of three who really takes pride in his lawn and garden. You'll find Andrew behind the scenes of almost everything Edge Your Lawn produces. When he's not helping readers find all the information they need, he's in his backyard working on his lawn and garden landscaping. This year he hopes to build an outdoor deck and sort out his veg patches.

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