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Maintenance is important for any tool, and lawnmowers are no exception, especially when you consider how many different parts can go wrong or break if they are not given the right kind of treatment. While the engine might be the most dangerous part in terms of how badly it can fail, the blade is usually overlooked, despite being a key part of the mower and something that can easily hurt you if you aren’t careful.
It might seem like your blade is fine as long as it is cutting grass, but that is not the case. Just because it can slide through blades of glass doesn’t mean that it is been properly maintained and sharpened, and it will eventually start to lower the quality of the lawn you are mowing. It will seem fine to start with, but eventually, you will find torn-up pieces of grass or uneven spots that require an extra pass, and it can even lead to your grass heading in a way that turns it brown.
We here at Best of Tools have created this short guide as a way to quickly tell you how to sharpen lawn mower blades, as well as some specific techniques or maintenance tools that might help.
When Should I Sharpen My Lawn Mower Blade?
Most people agree that sharpening the blade once per year is ideal for people who use their lawnmowers around their home garden, although it is worth increasing to twice a year (or even more) if the mower is seeing extra use. For example, if you are lending it to a neighbor or mowing a larger area than normal, you will want to keep the blades sharpened more often for maximum cutting efficiency.
In many cases, if you do it just ahead of the mowing season (a general term for the usual period, you begin mowing your grass, which is often in spring or summer). You should also perform blade maintenance more often if you are regularly going over the solid, bumpy or rocky ground since this is much more likely to damage the blades than pushing them through the dirt.
Preparing to Sharpen the Blade
Before you do anything with your lawnmower blades, you need to remove them. While certain models are designed to let you sharpen blades without removing them, it is still much more dangerous, and can often be quite awkward in small spaces such as garages or garden sheds. The exact method of removing the blade will depend on the design of your mower, but you can usually check the instructions to find out how you are supposed to do it.
Despite the differences between designs and models, the majority will involve a similar removal process:
1. Disconnect or remove the power source so that you can’t accidentally activate the mower. If it is a gas-powered motor, it is also a good idea to drain or remove the tank to prevent leaks or spills, too.
2. Turn the mower over in a safe way so that you can see the blade.
3. Wedge it in place with something – this is purely to stop the blade from turning, so you can use anything that’s solid enough to hold it up or keep it still.
4. Remove the nuts, bolts, and screws that keep the blade attached. Make sure that you keep track of which way it should be facing since not all blades are safe to use if you insert them upside-down.
5. Carefully clean the blade before removing it – this gets rid of any immediate dirt that could get spread about while you are trying to take it off. You can use whatever tools and chemicals you want, as long as they are safe and won’t interfere with removing the blade.
6. Take off the blade. Be very careful not to cut yourself, since lawn mower blades can be far sharper than a standard knife or gardening tool.
7. Put the blade in a safe place that makes it easy to clean. If you have a vice, it might be a good idea to clamp it in there – securing it properly is key if you want to make sure you will stay safe while sharpening it.
Sharpening the Blade
No matter how you do it, once the blade is out, there are multiple ways you can sharpen it. They all have their own pros and cons, but most of them will give you the same results eventually, so feel free to use whichever one you find most convenient or reliable. Here are multiple explanations of how to sharpen lawn mower blades, in no particular order.
By Hand
Sharpening a blade by hand requires as much safety as possible since you are literally putting your hands right against the blade. Make sure the blade is clamped down and secured as tight as possible, and make sure you are aware of where the blade is relative to your body at all times. As for the actual sharpening process:
1. Lay down something to catch and metal filings and dirt near the blade. A mask is also recommended for longer blades since the air will get quite dusty.
2. Start to sharpen the blade with a metal file. You can do this by running it along the blade’s cutting edge, stroking from the inside edge to the outside. Remember to do it on both sides if possible, since you will want to sharpen it from both sides if you can.
3. Re-insert the sharpened blade and secure it back in its normal position.
With Machinery
It is also possible to use specialized machines to sharpen your blades faster, although not all of them are specifically designed just for sharpening blades.
1. Wear eye, arm, and hand protection. Make sure that you are properly covered since machines will create more filings and shards than filing the metal blades by hand.
2. Set up the machine. Most people will use something like a bench grinder, which can take a short while to set up, but different pieces of machinery and equipment can take longer to prepare.
3. Start sharpening the blade. Like hand-filing them, you will need to make sure that each blade is handled in the proper way since doing it the wrong way or cutting into it at an odd angle can damage it more than it sharpens it.
4. If the blade starts to overheat, dunk it into a bucket of water. Most sharpening tools and machines will create a lot of friction, which can heat up the blade much faster than filing by hand. While it is unlikely to get hot enough to damage the blade, it still makes it harder to handle, so cooling it down is important for quick maintenance.
5. Put the blade back in the lawnmower and check that it is still rotating properly.
Then What?
If you’ve sharpened the blade properly, you shouldn’t have to do any more regular maintenance for a while. You will probably also notice that it is cutting grass faster, but this can be quite a subtle difference if the grass isn’t that thick. Make sure to keep an eye on how well it’s cutting things since any missed spots could be a sign that you have sharpened it incorrectly or it’s suffered some other kind of damage.
Keep in mind that sharpening the blade won’t solve everything: if it’s suffered extreme damaged or has started to wear down too far, you will be better off replacing it instead, since this is the quickest and cheapest way of getting rid of serious problems that aren’t just caused by dull blades or weaker cutting power.
