How To Sharpen Grass Trimmer Blades?

Written By James
Updated May 8, 2022 by James

How To Sharpen Grass Trimmer Blades?

Grass shears can be powerful pruning tools that can give your garden that cutting edge (pun intended). However, just like most tools these shears will need some maintenance. Blunt blades won't do you any good, so keeping them sharp and ready is vital for a clean yard.

How to sharpen grass trimmer blades? Grass shears can be filed, or sharpened with a sharpening tool. With correct preparation and technique, even the most abused garden tools can be restored to their former glory, making sure your pruning blade can still get the job done.

Although hedge trimmers can be sharpened to much the same effect, this guide will focus on grass shears rather than hedge shears. Sharp grass shear blades are usually reserved for the thinnest grass, helping perfect ornamental garden designs in your yard.

For denser grass, a grass blade can be used, sharpened by many of the same method. This is not to be confused with blades of grass, which is what you should be cutting. So if you're looking for proper grass blade maintenance to avoid blunt blades, look no further.


Dirty tools require a steady hand, especially when it comes to sharpening a blade. Prior to taking care of your blade, make sure you have all the suggested equipment readily available, and that you are following proper safety procedures. 

Blades with a sharp edge, especially larger ones such as grass shears, can just as easily cut your fingers as they can grass. Not to mention the potential further health risks which come with a rusty and unclean tool. So take care with your sharp tools.

A grass blade can be dangerous whether it has a flat or curved blade. Although uncommon, a curved blade can still be found in gardening equipment for thicker patches of grass. These are specialty tools, so don't expect to be trimming plant disease off healthy plants with such a large blade. Diseased plants are better handles with simple tools, with smaller blades.

In addition to your usual precautions, grass shears can be dissassembled for proper cleaning and sharpening. This is usually done with a bolt, nut, or screw keeping the two blades together in the centre. Remember the original positions of these blades however, as you will have to fasten them back together afterwards.

Suggested Equipment

For a simple job a flat, multi-purpose file will serve you well enough. Just like filing your nails, a metal file can restore the blade metal to a rust free state, and the blade edge to sharpness. As far as getting a tool for sharpening goes, this is by far the simplest option.

A vice or other means of holding a grass blade in place is also suggested. You will want the blade flat while you work it, and not gripping the blade handle properly can result in unwanted accidents. These are naturally best avoided when handling sharp edges and tools. 

Huge blades for gardening can be difficult and time consuming to sharpen with just a single cut file. So when sharpening blades consider using common household sharpeners. An ordinary scissors sharpener or a knife sharpener can seem like the wrong tools by name, but they will keep your edging shears sharp.

There is little worse than dull hedge clippers or hedge shears, so make sure you don't end up using the wrong tool for the job. Common household tools can get the job done, along with correct technique to sharpen the entire edge. 

An old rag and motor oil are also suggested to have handy. After performing the task of sharpening the blades, rubbing motor oil along your fresh blades with an old rag is a good way to prevent rust. Preventing rust build up will help prevent any rapid dulling as a result of poor or lacking maintanence. 


A bastard file is reccomended when filing your grass and hedge shears. Taking a starting position at the base, you should see a factory bevel. On the flat of the blade, file in an upwards motion against the blade. With a table vise, 10 inch mill file should be more than enough to cover the entire cutting angle.

Your original angle should be in line with the factory bevel angle, as a safety measure and general rule of thumb to keep your sharpening consistent. This precise angle is the most efficient for keeping the entire blade sharp.

Following the blade bevel is important, as grass shears are easily one of the fussiest garden tool to sharpen. Clamping down the entire tool to avoid slips and accidents when using a 10 inch mill file, half round file, or other bastard file will save you a lot of cuts.

After removing rust and sharpening your grass or hedge shears, it is suggested that you coat your shears with alcohol. This is a solid disinfectent, and will lower health risks associated with any cuts you do end up with in the future. Grass blades and gardening tools generally get very dirty, so this is good practice in any case.

If you don't want to use a file or are looking for some added safety between you and a sharp blade, then sand paper and a piece of plywood will do the trick just as well. Although a far cry from a power tool, the thickness of plywood is a welcome barrier between your fingers and the metal edge of the shears.

Sand paper and files are both similarly coarse and rough, allowing them to do comparable jobs at cleaning off rust and getting a pair of shears ready to cut again. It's also available in most hardware stores, alongside plywood, and other gardening tools. Everything you might need, in one convenient place. 

Scissor Sharpener

In much the same way, a knife or scissor sharpener can be used in the place of a half round file or similar. Pulling the sharpener from base to tip of your blade will ensure a smooth effort. Since sharpeners tend to be thicker and blockier than a 10-in flat "Mill Bastard" file, they also tend to be safer.

Your hands are kept further from the blade, and there is less necessity to file flat on the blade. You can essentially bypass clipper blades with household sharpeners, making your pruning tools all the better for it. Provided you sharpen correctly, with a complete stroke from base to tip.

Motor oil can also be used to prevent further friction. After you reassemble your blades when finished with the sharpener, check for friction or blockages by opening and closing the shears a few times. If they feel unduly stiff, then feel free to apply motor oil to the joint, and any other part where the blades intersect one another.

Advanced Tools

If you're feeling particularly advanced, then you may consider using a rotary tool. Although this is not something that is reccomended, a rotary tool could sharpen your shears effectively. A power tool that spins at high speeds, it would be a lot quicker than trying to file, sand, or sharpen by hand. 

However, not only could this be more dagerous, but a rotary is difficult to control. Metal on metal tends to spark, so you'd need not only a workshop with a tool in it, but specialised safety equipment. You also run the risk of ruining your edges, which would only force you into buying a fresh pair of shears anyway.

So, unless you're an absolute professional with a workshop and equipment to hand, a power grinding tool should be actively avoided. These tools are best left to those who know how to use them. Not to mention without hand filing to feel and follow the metal burrs on the blades, it may be difficult to know when you're done.

Proper Technique

A steady hand and patience helps the task of sharpening your shears far easier. You simply need to sharpen until you feel the metal burrs are gone off the blade, and can see no visible signs of rust. Afterwards, to reassemble your clippers, try to find a sharp burr near the base.

Once the sharp burr has been located, it should be noted that larger clippers may have a bolt or nut to keep te blades together. As such, a crescent wrench or similar may be required for assembly and disassembly. 

Fortunately, most standard wrench sizes are equipped for basic garden tools. You won't need a dedicated appropriate size box wrench to be searched for in a store, as a correct size box wrench will be easy enough to find. 

The trick reall is to follow the factory set bevel, as attempts to readjust the cutting edge will usually return lackluster results. Improper sharpening can lead to a less effective blade, which can make your gardening duties that much more difficult. In a worst case scenario, you can end up making your tools useless.

Your complete stroke motion should be done until you feel done, but the job is usually handled in ten to a dozen motions. If you're grass shears are especially bad then do not be afraid to go over this, or if you're just doing routine cleaning then go a little under. 

This process should result in a razor sharp edge, that can cut through tissue without even closing the handle. However, make sure to follow the process for both blades. Only sharpening one blade will do you no good when it comes to your gardening, and you'll be effectively stuck with half a tool. 

Safety Considerations

On top of standard blade safety, assembly of your grass blade can cause issues. Always make sure your fingers are not between the blades as you put them back together, nor as you close them. Although you may be eager to test how sharp your equipment now is, it is better to test it out on grass and weeds rather than your fingers.

If using power tools, make sure you are wearing the appropriate protection. Safety goggles and an apron for any sparks that may stray, but also work boots with a solid grip to avoid any slips. Any mishaps that follow the use of a power grinding tool can be devastating to your equipment, and do serious damage to your health.

Good grip will also prevent slips away from the quipment, which you'll want to avoid while handling sharp blades. Always be vigilant when moving with your shears for obstacles on the floor, which may be trip hazards. The old adage to never run with scissors doesn;t change just because the cutters get larger in size.

Disinfecting and cleaning your blade, and any injuries you may acquire over the process, is not just suggested but necessary. Dirty tools can carry all kinds of bacteria and parasites from the soil, so making sure you remain safe from not just cuts but physical illness as well is essential. 

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My father, and his father before him, and his father; for the past 3 generations, my family have always been into gardening. The green fingers is a gift passed down to me and I thoroughly enjoy it! I also have worked in the manufacturing department for Bosch and DeWalt so I like to think I know a thing or two about tools and such!
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