what angle to sharpen lawn mower blades

What Angle To Sharpen Lawn Mower Blades?

It’s one thing to get your lawn mower blades sharp and ready to cut but what a lot of people don’t realize is that you must sharpen the blade to a specific angle if you want it to perform to its best. But what angle to sharpen lawn mower blades is best?

Lawn mower blades come with a pre-existing angle which is normally around 35 degrees. You should stick to this when sharpening. However, there are some variations on this with angles as low as 30 degrees or as high as 45 degrees. This is why it’s important to follow your manufacturer’s instructions.

Getting the right mower blade angle is super important in ensuring that the blade cuts to the best of its ability. In this guide, we’ll cover the proper angle to sharpen lawn mower blades along with several other pieces of helpful information.

15 degree high lift blades are designed to produce more airflow. This means that the grass clippings are lifted within the deck as a result of the twist in the blade. This method is far better suited to lawn mowers that use a bagging collection method.

30 Degree Standard Blade

30 degrees is what you would call standard for a lawn mower blade. Generally speaking, they’re ideal for all round use and having a slightly steeper angle means that they are a lot more durable while still having a nice twist that creates that all important airflow. Unlike 15 degree blades, these are better for mulching mowers.

30 Degree Standard Blade​

45 Degree Blades

Some lawn mower blades have a very steep 45 degree angle which vastly improves durability. This characteristic also means that these blades are perfect for denser grass and heavy foliage. If you don’t need to create any lift, perhaps for a lawn with significant structure, then these blades are ideal. Where there is a lot of sand, the limited airflow can make cutting a lot easier.

Combination Blades

Only having one angle on a blade can limit how you use the lawn mower so it isn’t uncommon for manufacturers to produce combi blades that have a 15 degree and a 30 degree angle; these are normally called 2 in 1 blades.

How To Ensure You Get The Right Angle When Sharpening Your Blade

Sharpening a lawn mower blade is probably a much more detailed task than many people first realize. You’ve got to think about the tools you’ll use to get the job done as well as the right mower blade angle if you want the best results.

One of the biggest problems that people face is that they measure the incorrect angle and this can lead to all sorts of problems. So, before we go any further, let’s look at what we should be measuring.

Which Angle Do You Measure?

The angle within the blade is the one that you need to measure. You can use a lawn mower blade angle gauge to do this so it’s pretty simple, even if you’ve never done it before. The land-side is the one that cuts the grass and this is the surface you’ll want to measure.

In most cases, you’ll find that the mower blade angle is around 30 degrees. Although as I mentioned earlier, this can vary between models especially when considering their intended use.

Why Is It Important To Get The Right Angle?

The angle of your lawn mower blade is really important for two reasons. For starters, getting the proper angle to sharpen lawn mower blades is going to do your lawn a huge favor but it’ll also benefit the health of the blade itself.

If you don’t have the right angle then you’ll find that you don’t get much further than you would when using a blade that’s not been sharpened at all. These are just some of the reasons why it is so important to get the right angle.

  • If you don’t use the proper sharpening angle for your mower blades then it’ll tear the grass as opposed to cutting it. 
  • The finish of your cut will be much more ragged and uneven. This is even more likely if you are using a low lift blade. In the worst cases, you may find that the blade rips up patches of grass giving a messy final result.
  • When you allow blades to tear grass rather than neatly cutting it, this can damage the blades. A few days after cutting, you’ll notice that the grass is starting to turn brown.
  • Cutting your grass causes the plant to go into shock. When this happens, all of its energy is pushed into recovering from this. Usually, the grass wouldn’t have a problem but if it is being torn rather than cut, the stress can be too much and this can affect the health of the grass. For example, it may not grow as well, the root systems may be affected and in the worst cases, the grass will just die.
  • Since grass that is torn has open wounds and is much more stressed, this can result in it being more susceptible to disease. Of course, this could completely ruin your lawn and you may end up having to replace it. 

How Sharp Does It Need To Be?

Your lawn mower blade does not have to be razor sharp. In fact, this can do more harm than good. When a blade is turning at such high speeds, being too sharp can make it more vulnerable to nicks and damage. Generally speaking, you should sharpen it to around the same level as a butterknife.

What Should I Use To Sharpen A Lawn Mower Blade?

The great thing about sharpening your lawn mower blades is that there are several tools you might use to get the job done. The most obvious is to use metal files. You simply need to secure the blade using a vice and then pass the file over the cutting edge in even strokes. Keep the file facing downwards for the best results and avoid using a back and forth motion.

Some people choose to use their power drill which is a much faster way of sharpening your lawn mower blades. All you need to do is find a sharpening stone drill attachment and add this to your tool. One of the great things about this is that they come with plastic guides which help you to achieve the desired angle much more easily.

You will need to use ear protection and goggles when using your power drill. Again, securing the blade in a vice will make sure that it doesn’t move around during the sharpening process.

Finally, you might decide to use a bench grinder which is the faster and most efficient method for sharpening your lawn mower blades. The great thing about these tools is that they are far superior at smoothing out nicks and even work well where there are large chips taken out of the blade.

That said, it is best to use a slower speed and make sure that you keep a steady hand to maintain the cutting angle for the blade.

Final Thoughts

If your lawn mower blade is not kept sharp then it isn’t going to perform very well. Dull blades will rip grass, causing it to be unhealthy and potentially die. However, even a newly sharpened blade can cause similar problems if it is not sharpened to the correct angle.

But what is the proper angle to sharpen lawn mower blades? Normally, standard blades have a 35 degree angle. But there are blades whose angle is as low as 30 degrees or could be up to 45 degrees. Different angles have different benefits and should be maintained during the sharpening process.

If you are at all unsure, you can measure the angle using a gauge or simply check the owner’s manual which will contain all of the information you need.

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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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