Sharpening lawn mower blades: A guide
Dear lawn expert,
You've probably experienced this before: you're no longer satisfied with the mower's performance when cutting. Now you're asking yourself, how do I actually sharpen my blade?
Due to frequent use and driving over sticks, stones and other small obstacles, the lawn mower blade becomes blunt over time. If the grass frays at the cutting edge when mowing, there is a problem: the lawn mower blade is blunt and tears the grass off instead of cutting it cleanly. Frayed blades dry out more easily and are susceptible to disease.
Why it is important to sharpen the lawn mower blade
Find out here why it is important to sharpen your knife regularly.
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This is what you need for sharpening
Find out which tools are important for sharpening your lawnmower blade yourself.
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Sharpening the lawn mower blade
Here we show you instructions on how to sharpen your knife yourself.
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Why it is important to sharpen the lawn mower blade
- A lawnmower blade should be sharpened after about 20-25 hours of mowing. Don't wait until the cutting pattern is bad, otherwise your lawn will already be damaged.
- You can either sharpen lawn mower blades yourself or, better yet, have a professional do this service so that the blade is correctly sharpened at a 30° angle
- Always deactivate the drive of your device before sharpening
- When removing, installing and sharpening the blade, you should wear gloves and safety glasses for your own protection
- If you find a crack in the lawn mower blade after thoroughly cleaning it, nothing will help and you need a new blade.
So much for now…
We recommend having the blade properly sharpened by a specialist retailer https://fachhandel.stihl.de/ near you. This is the safest method of getting your lawnmower blade back to optimal operating condition. However, if you have the necessary manual skills, you can of course also sharpen your lawnmower blade yourself.
How do I sharpen my knife myself
Although your mower's blades are not precision tools and do not need to be sharpened to razor sharpness, it is not enough to simply restore the 30° cutting angle. If the mower blade has been sharpened, you must balance it - eye contact is not enough, these minimal tolerances cannot be seen! Your mower can suffer engine damage due to an imbalance and the associated vibrations.
And beware:
The warranty on the lawn mower blade is void if you sharpen it yourself.
If you sharpen yourself, you will need:
- a vice
- sturdy, well-fitting work gloves and safety glasses
- an open-end wrench without a ratchet
- a pipe wrench
- a file set, coarse to fine
- a grinding file or whetstone
- the right balancer
Safety first
Unplugging the machine, removing the battery or unscrewing the spark plug are always the first steps when working on the mower's blade. Put on gloves and safety glasses.
The petrol engine: a delicate matter when turning
You can easily turn electric mowers over and place them on the top of the housing. This is different with a petrol model: To prevent engine oil from running into the air filter, you should tilt it backwards at a maximum of 45 degrees - or place it on two chairs facing each other so that you can reach the lawnmower blade from below. The air filter must always stay at the top!
Sharpening the lawn mower blade
How to remove the knife
Your lawnmower blade is attached with a screw and can be loosened by turning it anti-clockwise. And be careful : when loosening the screw, you should always wear well-fitting gloves. You must hold your blade with one hand while you loosen the screw with the other. If that doesn't work, you must either ask a second person to hold the lawnmower blade or block the blade with a wooden wedge.
Now the knife is cleaned
The best way to do this is with a spatula or a wire brush. Once the blade is completely free of dirt and grass residue, you should check it for visible defects such as cracks or nicks. If you find any, the blade must be replaced.
Fix your knife in the vice
You do this in such a way that you can grind the cutting edges with an upward movement at a 30° angle. You should also put a pad between the vice and the knife.
We continue with the workshop file
This means you can trace the line of the blade in one direction to sharpen it. Do this until any deformations on the edge of the knife are no longer visible. And be careful : always maintain a grinding angle of 30 degrees and ensure that you sharpen evenly so that you don't grind in any imbalance.
Balancing
Now place the removed blade on your balancing device. If the lawnmower blade remains perfectly level, you have done a great job because it is not unbalanced and can be reinstalled. If the blade tilts in one direction, you must repeat the last step until the blade is perfectly level on the balancing device.
Reinstall
Replace the lawn mower blade and tighten to no more than 65 Nm torque
Frequently asked questions about sharpening lawn mower blades
The decision to sharpen the lawn mower blade yourself or to have it professionally sharpened depends on whether you have the necessary knowledge and tools. If you are unsure, it is advisable to have the blade professionally sharpened to ensure optimal sharpness.
You should have the lawn mower blade sharpened if you notice unusual vibrations or uneven cutting results while mowing. Regular sharpening is important to ensure clean and efficient mowing. Ideally, the lawn mower blade should be sharpened every year before the start of the gardening season or every 25 hours of mowing time.
The lawn mower blade is properly sharpened when the wings are pointing upwards and the blade fits centrally on a screwdriver. Also check that the blade is free of bumps and that it produces clean cuts when mowing.
Lawn mower blades become dull through constant contact with hard objects such as stones, roots or metal parts. Normal wear and tear can also cause the blades to lose their sharpness.
In some cases it is better to replace the lawn mower blade, especially if it has deep cracks or bends. Do not try to repair severely damaged blades, but invest in a new, high-quality replacement blade. We have a selection of different replacement blades from different manufacturers, such as Honda , Viking or Sabo .
Would you like to learn more about lawn mower blades? Then visit our blog and become a lawn expert!
Conclusion: A sharp blade is important for your well-groomed, healthy lawn!
Sharpening the lawnmower blade yourself is always worthwhile if it has not been in use for too many hours and the cutting edges are not damaged. But perhaps you should look for lawnmower blades that last longer due to higher quality. They may cost a little more at first, but the better quality pays off in the end and the idea of sustainability should not be ignored. You can find out whether there is something for your device on this page .
To all who can and want to do it themselves,
Your RasenExpert Team