If you’ve noticed your grass is ragged and unkempt, even after a fresh mow, you may need one of these tools to sharpen lawn mower blades. From hand files and sharpening stone attachments to rotary tools and bench grinders, we’ve got advice and information on all the tools to sharpen mower blades you need.
Depending on which tool you use, you may be able to simply tip your lawn mower to one side and sharpen the blades, or you may need to remove them first. You may also need extra safety equipment, such as safety goggles and gloves.
Our guide features five tools that will help you know how to sharpen lawn mower blades (opens in new tab), and we’ve consulted a top gardening expert for their tips on the best approach, as well as important safety precautions to take.
Top tools to sharpen lawn mower blades:
- Hand file
- Angle grinder
- Rotary tool
- Bench grinder
- Sharpening stone
And if you’re looking to replace your old lawn mower, or making the switch from electric, our buying guides to the best gas lawn mowers (opens in new tab) or the best electric lawn mowers (opens in new tab) are certain to have the perfect fit for your backyard, whatever its size.
We spoke to Fiona Jenkins, the resident gardening expert at My Job Quote (opens in new tab), and asked her for her advice on choosing the right tools for sharpening mower blades, and how to use them safely. Her first piece of advice is to make it a regular annual chore. “The best way to maintain your blades is to sharpen them one to three times yearly, depending on the frequency of use.”
Jenkins advises a gentler approach when it comes to sharpening mower blades: “Bench grinders and other such machinery do the job, but they can be a little too powerful for your mower blades. The best, most common, and controlled method for sharpening mower blades is to take the DIY, grinding by hand route. You can sharpen a blade by hand using a vice and a sharpening stone.”
Tools to sharpen lawn mower blades
Landscaper and gardening expert Fiona Jenkins says, “It’s always important to use a vice when sharpening the blades, to keep them firmly in place and avoid injury. You must wear long sleeves, gloves, eye, and ear protection while working with blades. This protects you from hearing damage, cuts, and abrasions from both the blade itself and the loose metal fillings that fly off in the process.”
1. Hand file
Using a hand file that’s at least 10 inches long, you can manually sharpen your blades, securing them in a vise for safety. Hold the hand file at an angle of about 45 degrees, which is usually the same angle as your blade’s cutting edge.
Using smooth, firm strokes, work from the inner to the outer edge of the blade. Continue until your mower blade is around the same sharpness as a butter knife.
A hand file allows good control of your technique and stops you from over-sharpening your blades. However, it requires a lot more manual labor and time than other tools in our guide.
2. Angle grinder
Often the choice for professional blade sharpeners, an angle grinder works quickly to sharpen the blade.
Secure the blade in a vise or to the edge of a workbench. Level the grinder at the same angle as the cutting edge on the blade and move it along the blade several times, using just light pressure.
Angle grinders are quick, cheap to buy, and fairly easy to use. However, you’ll need safety goggles and gloves, as angle grinders send up tiny shards of hot metal that can cause injury.
3. Rotary tool
Just like an angle grinder, a rotary tool can make quick work of sharpening your mower blades. These versatile tools are handy aids for sharpening, and you can use them on your kitchen knives or garden shears too.
As with an angle grinder, you’ll need a vise to secure your blade, safety goggles, and gloves. According to Dremel (opens in new tab), you’ll need a minimum speed of 15,000 RPM for sharpening, to avoid ‘bumping’ along the blade which can cause unevenness or dents.
Like angle grinders, rotary tools require extra safety precautions, and there’s always the risk of over-sharpening your blades, or not getting the same level of sharpness on each side, which can unbalance the blade and cause wobbling. This can damage your lawn mower motor.
4. Bench grinder
If you happen to have a bench grinder to hand, it can be a quick job to sharpen your mower blades using this heavy-duty tool. You will have to remove the blades from the lawn mower first, though.
Get your bench grinder up to its top speed and pass the blade across it, taking care to pass it over the bench grinder at the same angle as the cutting blade. You can use a finer grit afterward, to remove any dents or nicks in the blade.
It may be quick, but you need a steady hand to keep your blade at the right angle when you use a bench grinder. Too much pressure and you could damage your blade and need to replace it. You’ll also need safety gloves and glasses.
5. Sharpening stone
Most of us have a drill somewhere in the house. By adding a simple sharpening stone attachment, you can turn this DIY tool into a sharpener too. Sharpening stone attachments are readily available and are specifically designed for lawn mower blades. Just ask for one at your local DIY store if you’re not sure.
Insert the attachment into the drill and run the drill at full speed, slowly moving it back and forth over the cutting edge using light to moderate pressure. You may only need a handful of strokes to get that butter-knife sharpness you need for a clean cut.
This drill hack is easy to do, and you can even sharpen your blades without removing them from the lawn mower, although you may not get as clean a job. Don’t forget those safety goggles and glasses.
While you may think you need to hone your blades to a fine point, Jenkins warns that making a blade too sharp during filing can leave the blades prone to damage while in use, as well as being more hazardous to fit back into your lawn mower. She suggests dragging the sharpening stone over the edge to dull it down a little if you go too far.
And if you don’t want to remove your blades before sharpening, you don’t have to. You can manually sharpen the blades simply by turning your lawn mower onto its side and cleaning off any excess grass clippings before you start. Jenkins advises checking over the blades first and replacing any that look damaged or broken, to avoid injury. And of course, “always ensure that the power source has been disconnected before you begin.”
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