Sharpening the blade of a lawnmower should be done at least once a year unless the lawnmower was barely used.
However, majority homeowners find it to be an unnecessary, reasoning that a blade that’s a little dull can still cut grass. While this is true to some extent, it’s entirely beside the point; dull blades will often rip through the turf roughly and cause ragged, torn tips at the end of each grass blade. And will make lawn mower work harder.
The task of sharpening a lawn mower blade can be accomplished in several ways, including using a hand file, bench grinder, angle grinder or rotary tool.
RELATED – If you haven’t removed the blade yet, you may want to learn more here. We also recommend that you check out extensive list of various tools you can use to sharpen lawn mower blade with or without removing it. Also, is it time to replace the blade completely? Check here.
Before You Begin to Sharpen the Blade Make Sure:
For Gas Lawn Mower: Ignition wire from the spark plug is disconnected. It is also safe to empty gas tank to prevent accidental spilling
For Cordless Lawn Mower: Battery pack is removed to prevent the engine from starting up accidentally
For Electric Lawn Mower: Make sure power is disconnected.
Make sure to wear personal protective equipment (Eye Protection Glass, Ear Plugs, and Welding Gloves
Sharpening with Power Drill
Power drill is among the most common tool that every homeowner owns therefore sharpening lawn mower blade with the power drill can be very cost effective method.
Below are the steps for sharpening the lawnmower blades using a power drill. Similarly, Dremel tool sharpener attachment can also be used alternatively if you already own dremel rotary tool.
Once the blade is removed, use the vice and clamp the lawn mower blade on it. Ensure that one of the blade’s cutting edges is facing upwards before using the drill-powered sharpener on it.
The round abrasive stone comprising the sharpener features a sloping surface that allows it to grind the perfect cutting angle. Begin sharpening process by positioning the stone into the drill then proceed to sharpen the blade, slowly and carefully. This is achieved by moving the drill machine back and forth while applying moderate pressure on the blade’s cutting edge.
After 4-5 back-and-forth sharpening strokes, the blade should be sufficiently sharp. One should, however, remember that the blade should be as sharp as a butter knife rather than a razor blade. Making the mower blade too sharp could cause it to curl up upon getting dinged by the smallest pebbles. If the blade isn’t sharp enough, the homeowner should repeat the process several more times until all the nicks and chips are eliminated. Finally, one should remove the blade from the vice and rotate it to sharpen the other cutting edge. Make sure same amount of strokes are repeated on both sides as the blade must be balanced which is discussed in next step.
Having sharpened both cutting edges sufficiently, the lawn mower user can now proceed to balance the blade. This will eliminate the risk of mowing the lawn with a lopsided blade, which is caused by excessive removal of metal from one end of the blade than the other when sharpening. An unbalanced blade can potentially lead to excessive wobbling, ultimately causing damage to the motor. Not to mention putting undue stress on the machine. For this purpose, it is recommended to use a lawnmower blade balancer, which looks like a cone-shaped, multi-tiered metal fixture. If the blade is balanced, it will remain level upon placing it on the balancer. Conversely, the blade will tilt to the side if one end of the blade is heavier than the other, requiring extra sharpening.
Having sharpened and balanced the lawnmower blade, now you can reattach it back to the mower. At this point, also tighten up the retaining nut or bolt using the same wrench used to loosen them. The entire process is culminated by reattaching the ignition wire, filling the gas or reattaching the batteries and finally taking out the newly sharpened machine to the lawn for a test run.
Sharpening with Angle Grinder
An angle grinder is among the most versatile tools a homeowner can own; it can be used for sharpening, polishing and cutting through the required materials with remarkable ease. Armed with the right disc, an angle grinder often proves to be an effective tool for restoring sharp edges on the majority of household appliances, including lawn mowers.
Here are the steps for sharpening the lawnmower blades using an angle grinder.
After the blade is removed and safety precautions are taken as mentioned above, clamp the lawn mower blade to the working bench, either using a vice or C-clamp making sure that one of the blade’s cutting edges is facing upwards or sideways as depicted in the picture below, before using the angle grinder to sharpen it.
Once the blade is secured, test your grinder by plugging it in to the power and run it to make sure the grinder discs spin away from you. Thankfully, the grinder features an arrow indicating the direction to which the blade spins.
For this sharpening method make sure to wear protective gear like long sleeves, safety goggles and face mask. This will protect you from potential dangers associated with the use of grinder. It’s also important to wear earplugs; since the grinder makes excessively loud sounds.
Begin sharpening, by aligning the grinder’s disc with the lawn mower blade. This is done by positioning the grinding wheel perpendicularly to the blade; you must maintain this position throughout the grinding process. This is followed by starting the grinder and allowing the disc to spin at full speed. Subsequently, you should move the disc steadily along the length of the blade while applying slight pressure. Applying too much pressure while sharpening the mower blade could lead to excessive grinding of the edges and production of extreme heat.
While sharpening, run the grinder over the lawn mower blade several times until the cutting edges becomes sharp. However, it’s advisable to take small breaks while sharpening the blade because the heat produced by the grinder causes the blade to become brittle. If the blade becomes too hot it can be dipped into the water for cooling. If you require a sharper edge on the lawn mower blade than provided by the grinder, use mill bastard file for further sharpening.
Finally, make sure the blade is balanced by checking it with blade balancer which is imperative for proper working lawn mower. If you find the blade to be heaver on one side then remove excess metal to balance the blade.
Regardless of the type of lawnmower, homeowners are advised to keep their mower blades sharp at all times. This will go a long way in preventing undue yanking of the lawn as opposed to slicing through neatly and healthily. A sharp blade also guarantees the smooth operation of the lawnmower in addition to expediting the entire process of mowing.
Using the above DIY tips for keeping the mower blade sharp, homeowners can now face this seemingly daunting task with courage and look forward to a healthy, immaculate lawn.
Note: This guide applies to every brand of lawn mower such as Craftsman, Kobalt, Honda, EGO, Greenworks, Lawn Boy, Troy-Bilt, WORX, Husqvarna and many more.