How to Sharpen Riding Lawn Mower Blades

How to Sharpen Riding Lawn Mower Blades

It’s important that you know how to sharpen riding lawn mower blades if you own such a machine. Not only will this improve the efficiency of your mowing, it will improve the performance of your riding lawn mower.

Properly sharpened lawn mower blades are vital. Not only for the effectiveness of your cutting, but also to save unnecessary damage to your machine.

If a riding lawn mower, or any mower for that matter, has dull blades, the machine has to work that much harder to cut through the grass. This can cause overheating of the engine as well as other issues.

I recommend sharpening the blades annually at the very least. If you happen to hit some stumps or rocks, it’s worth taking a look to see if they blades need to be sharpened.

Remember, these blades are spinning very fast. Even a little nick can throw the blade off balance, and that is exacerbated by the speed of the blades.

For sharpening, you can either sharpen the blades on the machine or off.  Both choices have advantages and disadvantages.

Sharpening Riding Lawn Mower Blades on the Machine

First of all, sharpening the blades on the machine is quicker.  You don’t need to take the time to take the blades off of the machine. The bolts that hold the blades on are notorious for seizing, so what should be a quick process usually ends up taking longer than expected.

The downside is the access. In order to get at the blades, you need to lift the machine and the deck off the ground. This can be accomplished with a lawn mower lift, but not everyone has one.

If you opt for simple ramps to lift the machine off the ground you can have access – albeit limited.

Tools Needed (Commissions Earned)

With cramped space comes a lack of visualization. It’s important to be able to see the blade, more specifically, the bevel of the blade when sharpening.

You want to follow the bevel of the blade and keep that same angle.  You can choose a hand file, a hand drill with a specially designed sharpening stone, or my preferred method – an angle grinder with a flap disk.

Just remember to keep the same angle and if you’re using power tools, be careful not to remove too much material.

The downside of sharpening the blades on the machine is that it’s just that – on the machine.

Like we mentioned, the lack of space is a problem. That usually results in less than optimal sharpening.  Furthermore, you don’t have the luxury of being able to balance the blade afterwards.

Sharpening Blades Off the Machine

This can be a slower process, but it also gives you the chance to do a better job. By forcing yourself to slow down, you can get a more even sharpness and you can balance the blade afterwards.

Taking the blades off the machine can be problematic if the bolts are seized. Furthermore, the blade is going to want to spin as you rotate the bolt.

If you’re just using a socket, I highly recommend some heavy duty welding gloves if you’re going to attempt to hold onto the blade.

A better option is to use an impact driver. The impact can force the bolt out without spinning the blade, and it’s a much safer choice.

Once the blade is off the machine we have many of the same options for sharpening.

By placing the blade in a vise, you can sharpen it with a hand file or the aforementioned power tools.

Another popular choice is to use a bench grinder to sharpen lawn mower blades.

This is a great choice if you’re sharpening several blades as it is quick. However, I recommend this option only for the experienced sharpeners out there. While it may be fast, it’s also easy to remove too much material and it can be dangerous if you’re inexperienced.

The last step is to remember to balance the blade with a simple blade balancing tool. These are inexpensive to pick up, so it’s worth doing so. An unbalanced blade can cause damage to your machine.

If one side is heavy, just remove a little more material from that side only until it’s balanced.

Recap

There are several methods for sharpening riding lawn mower blades.  Ultimately, it doesn’t really matter how you do it, just remember to do it. 

Typically, I like to remove the blades for an annual sharpening at the beginning of the season.  While this is more work, it lets me do a better inspection and to get a more consistent sharpness on the blade.

Throughout the season, if I happen to hit some rocks or bury the blade in the dirt I’ll do a quicker sharpen with the blades on the machine.

Now that we’ve discussed a few different ways to sharpen your riding lawn mower blades, I hope you remember the most important part: be safe; riding lawn mower blades, even dull ones, are sharp enough to cause serious lacerations.

Did I forget your favorite method for sharpening blades? Let me know in the comments below.

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