Can lawn mower blades be too sharp?

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A lawnmower is an indispensable garden tool. With a good one, you are assured of well-manicured lawns in your homestead. Overgrown turf is unsightly and harbors pests, thus, before you mow grass, ask this question: which factors determine the optimal performance of a good mower?  Optimal performance is all about the efficiency of lawnmowers. In this post, we answer the question; can lawn mower blades be too sharp?

The best answer we can give is that lawn mower blades should not be too sharp. Rather, they should be sharp enough to cut grass seamlessly. With sharp blades, you get clean cuts. Compare it to using a sharp knife to cut veggies or a sharp razor. You realize a sharp cutting tool performs exceptionally well, albeit, there are risks associated with using sharp knives or razor blades.  

With mowing blades, sharpness depends on many things such as type of turf and lawn terrain. This post has more, so dive in to learn more as we help you explore more about mower blade sharpness.

How sharp should lawn mower blades be?

When the blades are too sharp, they become blunt quickly, albeit that may depend on blade thickness. With blade sharpness comes many other questions such as how sharp should the blades be? You may want to call it a question of what if. However, if you are planning to mow a yard full of weeds and soft grass, sharpening the blades to an extremely low angle is the best thing to do.  Keep the blades a little duller when working on the woodsy or rugged lawn.

Most importantly, with blade edges, the angle of sharpness should always be 40 degrees but not less than 30 degrees. Anything below that inclination qualifies as too sharp, hence more susceptibility to small stones, soil, and pebbles. The bottom line is that how sharp a lawnmower blade is should depend on the nature of grass and terrain of your backyard. A simple rule of thumb from us is that the level of sharpness (edge bevelling and angling) should remain as it were when you bought your lawnmower.

Do sharp mower blades make a difference?

Yes, sharp blades make a difference-a very big different, to say the least. During spring, when grass grows fast and becomes bushy, only sharper blades will do a great cut with minimum strain on your lawnmower. You also realize faster mowing with sharp mowing blades. Thus, we would say, the sharpness of lawn mower blades do matter. To help you understand why sharper blades make a difference, take note of the following:

  • Nicked or dull lawn mower blades will only smash grass on the cut edges. It means, instead of clean straight cuts, your lawn will end up with torn grass. You don’t want to have an unsightly rugged lawn, do you?
  • Torn grass means a few days after mowing; your lawn becomes brown as the grass dries on the torn edges.
  • Nevertheless, smashed, torn and brown grass is susceptible to diseases and pest invasion, something that will push lawn maintenance a little high. We bet you don’t want to go that route, at least not now.

Sharpening lawn mower blades: How to do it

You should always inspect lawn mower blades for sharpness. While blunt edges are easy to detect going by how they cut grass, experts advise you check blades for sharpness at the beginning of spring (the season of mowing). Some signs of blunt blades are dents, nicks, and bends. Blades that split grass leaving them rugged and brown after a few days are often blunt.

Moreover, take note that clearing yards before mowing help keep blades sharp for long.  Inspect your yard and remove debris, stones, rocks, and sticks that would nick blades. The following are steps to follow when sharpening lawn mower blades:

  • You should wear protective gear when sharpening blades. They include safety glasses and gloves that are resistant to cuts.
  • Make sure to disconnect spark plugs on your lawnmower. It is to guards against a possibility of the machine starting on its own.
  • You will require tools such as rags, vise, and ratchet set/socket for this task. A sock for the spark plug is equally necessary. Other items you need are gloves and a lubricant, preferably WD-40.
  • If your lawnmower does not have a user manual that walks you through a stepwise guide on how to sharpen blades, do not fret. Our guide should see you through.
  • Get hold of a good grinder to sharpen the blades, but for the nicks, a good file should flatter them.
  • Use a vise to secure the blade. Use a grinder, file or any other sharpener to remove dents/nicks before sharpening the edge.
  • When sharpening blades, balance them properly. It is as important as having sharp cutting edges.
  • Sharpen lawn mower blades in one direction, at a bevelling angle of 45 degrees. However, you can go further to 30 degrees depending on the terrain of your yard. We advise that you keep blade sharpness the same as that of a scissor. 

Important points to note about sharpening lawn mower blades

  • Remember that sharpening lawn mower blades too often could mean you replace them with new ones every few months. However, from our experience with good mowers, a good one with properly tempered blades should last for a year or more. On this premise, genuine ones should mow for 1-3 years even with frequent sharpening.
  • Keep sharpening frequency to the minimum possible, say after the 8th mowing. But depending on the model of machine you are using, blade tempering and other factors, you may have to flatten nicks frequently. The bottom line is that most experts advise that homesteaders should sharpen mower blades at least twice or at most four times a year.
  • Should it prove challenging sharpening and balancing lawn mower blades the right way, consult a service provider for professional help. It should cost only a few bucks usually less than $10 depending on the condition of the blade.
  • Balancing guards against vibration hence no stress on the cutting deck and engine so do it before reinstalling the blade. A balancer tool should help you realize even weight distribution on the blade. While you can get a good balance for about $5, feel free to choose from among competition provided you get value for your money.
  • You should have a habit of keeping the sharpness of a mowing blade optimal. Thus, always store tools for this task in a place where you can access them when the need arises.

Why do mowing blades lose sharpness/get dull

You will not wake up one day and say, ‘I’m sharpening my lawnmower blade.’ Whether you have a push mower or one on which you ride, important decisions that involve improving the efficiency of machines should not be abrupt. Nevertheless, factors that contribute to dullness of mower blades include but are not limited to the following:

  • Infrequent and Irregular sharpening

While you should sharpen blades all the time, leaving them unsharpened amounts to infrequent sharpening. You will find the task harder next time, say after six months if you don’t sharpen frequently. Now, when it comes to sharpening blades irregularly, it means unevenness of edge bevelling/angling. Thus, irregular sharpening often makes blades go dull faster than you would expect.

  • Thin blades vs. thick blades

Thin blades lose sharpness faster than thick, hence require frequent sharpening. Let’s reserve a discussion on thin vs. thick mower blades for another day.

  • Wear and tear

Mowing blades, like every other part of a lawnmower, undergo wear and tear. The more they hit rocks, stones, sticks, and pebbles, the duller they become.  

  • Mowing grass nearer the ground

You should expect mower blades to become dull faster if cut grass too close to the ground. The catch here is that while you would want to cut the grass shorter, doing so makes blade susceptible to stones and pebbles, hence lose sharpness faster than cutting grass higher.  

When to replace mower blades

While it is important to keep mowing blades in great condition, a concern arises. Under which circumstances should you replace the blades? Also, which factors play significance when making such a decision? The truth is that even with the best mowers in the market, these machines do wear and tear. After a few years of use, the replacement of worn-out parts becomes necessary.

Now, on replacing worn-out blades, there are a few things to keep in mind. First, you should use an exact replacement blade, preferably from the same manufacturer from which you bought a brand new mower. Old blades that have a thin trailing edge need replacement. Another factor to consider is the cutting edge, so always ask the question; will further sharpening cause an imbalance on the blade? If it will, it is that time you bought a new one.

Final Thoughts

In a nutshell, you have learned that mowing blades can be too sharp. Blades that are too sharp become blunt faster than fairly dull ones. Thus, you should choose thicker blades over thinner ones to avoid frequent sharpening. They should be sharp enough to do a clean cut with great ease and not too dull to leave freshly cut grass looking unsightly.