How to put the knife on the grass trimmer

How to put the knife on the grass trimmer

With the arrival of summer, many homeowners are worried about the question of how to put a knife on a grass trimmer. No less relevant are the questions of why and when it is advisable to replace the line on the brushcutter with a more durable cutting element. In our article we will try to disassemble all this and give useful recommendations to summer residents.

Why put a knife on a grass trimmer

A grass trimmer with a knife mounted on it is most convenient to use for more comfortable mowing of tall and coarse grass in the country. The fishing line on the brushcutter does not cope in such cases. Thin tears very quickly. Using 2.3mm thick cord or homemade rods with cables causes the vegetation to wrap around the spool. This increases the load on the engine. As a result, the piston group and other moving parts of the unit wear out very quickly.

If the weeds are mowed with an electric trimmer without a knife, only a fishing line, even a thick one with a curly section, will not solve the problem. There is always a risk of overheating the motor and damaging the flexible shaft. And it’s all about the large torque of the electric motor. Grass wrapped around the spindle creates a strong resistance to the shaft, which resembles a speedometer cable, which does not withstand and twists.

In order to protect the equipment from premature wear, manufacturers have provided for the possibility of installing special knives on grass trimmers. The design and shape of the existing cutting elements allows you to easily cope not only with coarse and overgrown grass, but also successfully deal with young shrub growth.

What knives to put on an electric and lawn mower

Before buying and putting a knife on the brushcutter, we will find out what they are and in what cases they are used. Today manufacturers offer the consumer a large number of types of these consumables. In general, all cutting tools designed for mowing grass can be classified:

  • By the type of material from which it is made;
  • By the shape of its cutting blades.

How to attach a blade to you Brush cutter attachment

The main material for the manufacture of trimmer knives can be plastic or metal. The use of such consumables largely depends on two parameters:

  • Type of brushcutters;
  • Mowing areas.

For safety reasons, manufacturers do not recommend using steel blades on electric grass trimmers. Almost all brushcutters powered by an electrical network and a battery are equipped with plastic blades. Depending on the manufacturer, they can be of a solid disc-shaped design, with several blades or in the form of a special mowing head providing for the installation of removable plastic blades.

The straight bar for the petrol grass trimmer and the curved bar for the electric

To put a metal knife on an electric grass trimmer is not allowed by its design features.

  • The curved bar of the machine reduces the distance from its working part to the mower’s feet. In the event of a collision of the blades with a stone or other solid object, the grass scythe is thrown at the feet.
  • The high torque we mentioned above, in the event of a metal blade hitting a hard object, transfers a lot of load to the grass trimmer’s flexible shaft and motor. What causes them to fail prematurely.
  • The handle of the electric scythe most often does not have a limiting bar acting as a stop. Which does not exclude injury to the legs.

It is these features that make it possible to use exclusively plastic knives on trimmers with electric motors. When colliding with an obstacle, the blades are destroyed, thereby protecting the mower’s legs from possible injury.

Plastic knives do a good job on overgrown and dry grass. They can mow nettles and burdock stalks.

The use of metal knives only on gasoline trimmers is also due to design features.

  • Straight bar design increases leg clearance for complete safety.
  • Comfortable U-shaped and J-shaped handles provide a firm grip. The D-shaped handles of the brushcutter are equipped with a limiter that rests on the leg of the mower, which does not allow the head to come close to the feet when the cutting disc meets a solid obstacle.
  • The clutch of the gasoline engine allows for smooth acceleration to the optimum level. And when the blade hits a hard surface, it is able to absorb part of the impact.

Thus, gasoline grass trimmers with a metal blade installed are best used in large areas. They will successfully cope not only with high coarse grass, weeds, burdocks and nettles, but also shrubs, as well as young trees.

The shape of the blades of the disc supplied to the grass trimmer does not in any way affect the quality of the work performed. Speed ​​does not depend on them either. Triangular, trapezoidal, rectangular shapes are all the marketing ploy of manufacturers.

If you are planning to harvest hay, it is best to use knives with a large number of blades on the brushcutter. Note discs with eight teeth or discs with four large blades and four additional blades. Two and three bladed knives will chop the grass hard.

How to put a knife on the grass trimmer correctly

Putting the knife on the grass trimmer is not that difficult. The manufacturer completes its tools with a special pin that allows you to block the gearbox and a wrench with which the spool and fishing line are unscrewed. The most important thing is to observe safety precautions and the sequence of assembly and disassembly when changing cutting elements.

The algorithm for attaching the knife to the grass trimmer is as follows:

  • Remove the protective cover;
  • We block the drive. To do this, it is necessary to align two holes. in the shaft hub and in the gearbox cup. After combining them, insert a pin into the holes;
  • Unscrew the spool with line or the attachment nut holding the boot in a clockwise direction from the hub (if the grass trimmer has not been used yet);
  • Next, we install the cutting knife, so that the slots on the hub washer coincide with the recesses in the hole of the cutting disc;
  • Install the boot;
  • We tighten the fastening nut (counterclockwise) while holding the locking pin;
  • We tighten it using a tubular wrench;
  • Putting back the protective cover.

As you can see, there is nothing complicated. Now you can safely start mowing weeds on the site.

The better to mow the grass

Before installing the cutting attachment, consider what you will be cutting. If fresh grass, then the answer is unequivocal. choose a fishing line.

The line is a thin nylon thread. It is also called a cord, string or wire. The mowing head has a spool (reel) inside, on which this wire is wound. The spool is mounted on the shaft, the motor speed is transmitted to it through the gearbox. The ends of the line are exposed. When the spool rotates, they also rotate with tremendous speed and force. This is how the grass is mowed.

Cutting widths range from 40 cm to half a meter. The wider the wire mows, the faster you mow the lawn.

The line cuts well at any height. even the tallest that the lawnmower cannot handle. In general, there are many places where the lawn mower will not pass. narrow spaces, lawn edges, near curbs, flower beds, under benches. All these are places for brushcutters with a string tucked into it.

The wire is especially effective when mowing grass in the garden, since it only easily glides along the tree trunks and does not harm them.

It is convenient to mow grass for hay, but if the vegetation is tough and dense, use a knife.

Types of steel knives

Not all brushcutters are designed to be fitted with discs or blades. In order for the engine to “pull” the knife, it must be powerful, at least 1-1.2 hp. In addition, a rigid forged shaft must be installed inside the boom. If you have a gas-powered grass scythe or an electric grass trimmer with a curved bar, then the inside of it is not a metal shaft, but a cable. He will not stand a knife. it will burst right there.

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But, if everything is in order with the scythe, and the manufacturer provides a knife in the kit, then feel free to use it.

The knife is indispensable in case:

  • mixed vegetation;
  • the presence of dense and tough growth;
  • an abundance of hard weeds;
  • cut stalks of corn, sunflower;
  • germination of fresh shrub shoots.

The cutting principle is the rotation of the knife on the shaft. The cutting width, as a rule, is standard for all brushcutters. a quarter of a meter, but there are knives and larger in diameter.

By design, the blade for the brushcutter is bladed. Blades are sharp blades that are sharpened on both sides. There can be two, three, or four blades.

  • The two-beam one resembles a plate. Lightweight and suitable even for household trimmers;
  • Three-lobed. the most popular for cutting weeds. It has a small base and three long blades;
  • The four-beam differs in that its base is larger, and the blades are shorter. With this design, less grass is cut, which is important when mowing for hay, since finely cut hay is difficult to collect later.

The more blades, the higher the mowing performance. After all, it is the blades that effectively cut tough vegetation.

Often, to increase the strength of the knife, victorious solders are applied to the blades. Such a knife element is much stronger and more durable. But it is also heavier in weight. Therefore, do not rush to install a multi-blade knife if, for example, mow soft clover. Better save it for vegetable gardens where you need to cut thick and tough corn stalks.

When mowing with a knife, carefully inspect the area. if there is any treacherous stone or a hard bump. If you stumble upon it, you will break or warp the knife, and the engine will stress too.

Which cutting system for brushcutters is better: line knife or disc

Mowing lush green grass with fishing line is easy and pleasant. Even fun. But it is worth stumbling upon dry, tough stems, and the fun will diminish. Such a task is beyond the strength of the line. It just slips, and the weeds remain intact. You need to replace it with a knife. That is why high-quality and powerful brushcutters always have a removable cutting headset in the kit: fishing line, knife and disc, for example, on the website you can conveniently and quickly pick up a braid with any cutting system, make sure of this ourselves, but we do not leave the topic and read on.

What is the best line diameter?

For grass that is different in freshness and softness, you need a different diameter of the fishing line (cord). But let’s say right away. carefully read the technical data sheet of your device. If the manufacturer has indicated that the permissible line is not more than 1.2 mm, then do not try to wind a 2 mm one. Do not mow for a long time. The engine will overheat due to load.

The diameter of the brush cutter cords sold in Ukraine is in the range from 1.2 mm to 4 mm.

  • 1.2mm. 1.6mm. Slim. It is used for lawn maintenance, constant and frequent mowing. Most often recommended for electric trimmers, 0.5-0.7 kW.
  • 2 mm. 2.4 mm is the most popular cord option. Suitable for medium power units. the most common among summer residents. Cuts both young and old grass, tough and mature.
  • 3mm. 3.2mm suitable for heavy duty professional gasoline scythes. Thick strings easily handle even coarse weeds and dead wood.
  • 4 mm is the thickest. Some aluminum is added to the nylon for strength. It is rarely used, since the engine power, as a rule, puts restrictions on a given diameter. But, if the engine allows. refuel and cut the weeds.

Manufacturers often paint fishing lines of different diameters in different colors. green, blue, orange, to make it easier for users to understand. The bay area is from 10 meters to 100.

Section. what affects the shape of the line

The shape of the thread also affects the mowing result. Like the diameter, it directly depends on what exactly you will be mowing. The cutting edge is by section:

  • Round. Most common. It mows both dry grass and fresh grass well. One of its advantages is low noise, but users say that this characteristic is not important, since the growling gasoline engine drowns out all other sounds.
  • Polygonal. The section can be triangular, square and even hexagonal. The pluses of the polygon are sharp cutting edges. They better interrupt rough stems, even young shoots of a bush. Hence the highest productivity. Less. used up too quickly.
  • Figured. The section is intricate, ribbed. It looks like an asterisk or a twisted square with grooves, in general. a complex geometric figure. This is a specialized cord. Each comes with instructions on what exactly he cuts. For example, an asterisk. ideal for cutting lawn grass. Although it costs a little more, it cuts neatly, the tips of the grass cover look attractive and do not dry after cutting.

What to mow with a toothed disc

If a knife has eight or more blades, then it is already called a disk. The number of teeth ranges from eight to forty. The multi-tooth disc is made of strong steel. Sharpened on both sides. Its base is large, and the teeth are small and sharp. It works like a saw. it rotates and cuts. The disc must be installed very carefully. evenly and well fixed.

The saw blade is needed for cutting thin tree trunks. Even a fully formed trunk can be cut down by carefully sawing it from different sides.

But the disc is intended not only for cutting down young growth of trees. You can easily mow them and grass for hay. Especially dry and tough. The main thing is to choose the right disc. lightweight and with a perforated base. Then the grass is not cut strongly. This is important when cutting short grass for hay.

If you are going to cut trunks, you can install a circular disc. He cuts great, especially if the teeth are slightly spread. But when installing a circular disc, you are at great risk. There is a risk of ditching your tool, since the load on the gearbox increases tenfold. A powerful engine (2-3 hp) will pull such a disk without any problems, but the gearbox. it is not clear how it will behave. Therefore, such a change can only be done if you are sure that the gearbox is durable and professional.

How easy it is to wind the line around the trimmer head

The spool can be wound from 3 to 10 meters of wire. In the process of mowing, the nylon thread is erased, you need to expose new ends. There are several ways to accomplish this task:

  • Manual. To do this, you need to stop working, remove the spool cover and set the desired length. The process is simple, but it does not add to the speed of mowing.
  • Semi-automatic feeding. With this method, the new tips are exposed independently. To feed them, you just need to lightly hit the head on the ground. The anchoring mechanism is triggered and you can mow again. This option is a win-win. You do not need to stop the engine, stop mowing, and the feed is strictly regulated, therefore. economical.
  • Full automatic machine. A very convenient way. you simply reduce the speed and the ends of the cord are replaced with new ones. The system takes care of this on its own. The speed of work is greatly increased. But there is a small drawback. a large consumption of fishing line. You can’t control it.

When the thread runs out, you need to wind a new one. Refueling methods also differ. There are two types. manual and quick charger.

The most common is manual. Step-by-step actions:

  • Unscrew the mowing head. Open the lid. There are latches on the sides for this.
  • They remove the coil, as a rule, information is applied on it, what diameter, into which hole you need to push. An arrow is also drawn indicating which direction to wind.
  • Inside the coil, in the middle there is a side. There is a groove on it for threading a loop.
  • We measure the length of the wire. Online users are advised to cut off 3-4 meters, no more. Since the winding is too tight, it is ineffective. Also remember that the thicker the line, the less you need to wind it.
  • The cut cord is folded in half. A loop is threaded, fixed by the bracket. The coil is held by the spring from itself. Hand-wound counterclockwise. You need to do it tightly and evenly. One thread lies at the bottom of the spool, the other at the top. The turns must not intersect.
  • The tips are inserted into the holes and exposed to the outside. Spin the coil. And the head in place. Fit the ends hitting the ground.
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Sometimes the reel is designed to wind up two separate pieces. This can be seen when the coil is opened. In the middle it has a high ledge, and there are two holes for fixing. The method is, in principle, the same, but we divide the thread into two parts, fix the staples in the spool and wind.

The fast charging method is better, it differs in both speed and comfort. There is no need to disassemble the coil. It is enough to tuck the loop into a special hole and turn the mechanism. He himself will wind the line on the reel. All that remains is to adjust the tips.

Brushcutter knife. Brushcutter knives. what for what.

Regardless of the principle of operation of brushcutters, electric or gasoline, none of them will work if there are no knives. After all, they are the main cutting part in the entire mechanism. To choose the right grass trimmer blade, you need to have some knowledge in order to make the right choice. We are talking about the diameter, dimensions, as well as about its capabilities, which is very important in the future when performing work.

The brushcutter is based on a bar. At one end of it there is a motor in the upper part, and a head together with a coil on the lower part. And also the line is tucked into the grass trimmer. It plays the most important role in the mowing process. over, regardless of whether the plants are wet or dry. Also, the line copes with cutting trees, posts, fences, leveling surfaces, lawns, etc. Well, as for the sprouting shoots of shrubs, reeds, as well as young trees, in this case, the knife of a garden grass trimmer will be ideal.

And so, in what cases is this or that used?

If you need to mow lawn grass, you can use a plastic mowing head (spool with line) or a metal mowing spider.

To mow grass, weeds or shrubs, use a 2, 3 or 4 bladed knife:

You can also use an eight-toothed knife to mow hay, grass or reeds. A forty-tooth or eighty-tooth knife is suitable for mowing overgrowth and reeds. A forty-tooth knife, which has a victorious soldering, is quite powerful, among those that come with a circular saw, it is convenient for them to cut trees and shrubs.

When choosing a grass trimmer knife, pay special attention to the diameter and thickness of the knife:

It should also be borne in mind that the diameter of the saw blade of the cutting knife is very important. Depending on how difficult the task will be for the brushcutter, the larger the diameter of the knife should be chosen. And in order not to harm beneficial plants growing near the mown plants, you should choose a smaller knife.

It is not recommended to save in the case when the blade of the garden grass trimmer becomes dull. If you sharpen it yourself, it can deform, as a result of which the centering of the knife will be disturbed. As a result, there is a risk of injury while using the tool. And 30 minutes after working with such a brushcutter, your hands will be very tired.

Knife or fishing line. what to choose?

The lawn is able to decorate any country house. However, in order for him to look like a king, he should be provided with competent care: fertilizing the soil with fertilizers, regular watering and constant “haircut”. If you do not mow the lawn, then after a while, the beautiful and blooming green “carpet” will turn into thickets of unkempt shrubs. Thanks to such a modern invention as the garden grass trimmer, the treatment of the site has long ceased to be dull and mundane. This tool has excellent mobility and maneuverability, and the motor installed in the device will help to do all the work in the shortest possible time.

Gasoline, battery or electric: which one to choose?

  • electrical;
  • rechargeable;
  • gasoline.
  • Great freedom of movement. During operation, the electric cable does not interfere with the cutting of the grass and there are no restrictions on the length of the cord. Petrol grass trimmer allows you to cut grass even farthest from your home.
  • High power. Brushcutters are capable of removing stems from vines and shrubs and can handle the toughest grass with ease.
  • Large amount of work. Thanks to the petrol cutter, farmers will be able to mow grass for pets in a short time.
  • loud noise during operation;
  • non-ecological device. during operation, the gasoline grass trimmer emits a large percentage of exhaust gases that contribute to environmental pollution;
  • inefficiency, which is expressed in the constant refueling of the lawn mower with a gasoline-oil mixture;
  • heavy weight.

The Electric Grass Trimmer is a lightweight and mobile device that does not affect the environment and does not require a significant investment in fuel. Nevertheless, with all its advantages, it also has its disadvantages, namely:

  • low power, which does not allow the removal of thick branches and shrubs. This parameter ranges from 200 to 1500 watts. The grass trimmer, which has the lowest power range, is only suitable for cutting lawn grass, but for weeds, you will have to choose a tool with more power. A device with a capacity of 1000 watts is considered universal, it will remove both delicate grass and tough weeds;
  • connection to the power grid. In the case when you need to cut the grass that is at a great distance from the house, and the cable length is not enough, you will have to use extension cords, which is not very convenient.

The trimmer is operated by a battery built into the device. Battery charging is enough for 20-30 minutes of uninterrupted operation.

  • ease and ease of use;
  • high level of maneuverability that allows you to remove grass even in a hard-to-reach place;
  • does not require fuel and is not tied to the electrical network;
  • has a low noise level.
  • has a low power, which does not allow removing tough and tall grass;
  • has a low performance, since after half an hour, it requires recharging.

When choosing a grass trimmer, you should pay great attention to the cutting system, it can be of two types:

  • fishing line;
  • metal knife.

The line is wound around the bobbin inside the spool. When the engine is running, the bobbin rotates, and the ends of the line, which are exposed to the outside, cut the grass. Despite the apparent fragility, the line easily cuts off an unnecessary layer of grass, thick weeds, and even is able to cope with shrubs. However, in the process of work, the line may wear out. With automatic feeding, it will be replaced by itself. If, however, a semiautomatic device is installed in the trimmer, you will need to hit the reel on the ground, and the system will release the ends of the line out.

When working with a fishing line, a number of rules should be observed:

  • Never touch the line or spool to hard materials. When touching a curb, fence or stone, the line will be shortened ahead of time and the reel may be damaged.
  • Removing weeds with the ends of the line will be much more effective than using the entire length of the line. In addition, this action is fraught with damage to the coil.
  • Too tall grass, exceeding 20 centimeters in length, requires several mows. The mowing of the grass should be done from top to bottom, this manipulation is required so that the grass does not wrap around the reel.

A metal knife is installed in trimmers in cases where the engine cannot cope with high loads. Therefore, a knife can often be found in a petrol cutter rather than in an electric trimmer. The knife can be two-, three- and four-bladed, it easily cuts both hard weeds and branches, and if you install a special disc with teeth on the grass trimmer, the device will overpower even strong young trees.

In an electric trimmer, the engine can be located both in the upper part of the base and in the lower.

The motor located at the top of the grass trimmer is considered to be the most convenient and comfortable, it can cut wet grass. This type of device implies only work with both a fishing line and a knife.

The bottom engine also has its advantages. Such a grass trimmer can be used even by the elderly, it is more handy and convenient to use. However, mowing wet grass is prohibited as there is a risk of electric shock.

knife, grass, trimmer

Comfort and convenience are the key to fast and high-quality work

The use of the tool should not be heavy, so before purchasing a grass trimmer, you should decide on the shape of the handle. The handle can be made in the shape of the letter D or T.

A device with a D-shaped handle will allow you to cut grass in small areas that require an unnecessarily high degree of maneuverability and agility.

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The T-shape can make the job much easier as it resembles a bicycle handlebar, which allows the operator to hold it with two hands and less fatigue.

Devices with high power are distinguished by their large weight, which can reach 5 kilograms. Less powerful grass trimmers will not be able to trim hard stems, but the light weight will allow even the weaker female sex to operate the device.

Summing up, I would like to note that there is no universal device that could fit any conditions. When choosing a grass trimmer, you should take into account all the nuances: the size of the site, the grass that grows on it, the presence of stones and trees.

If the suburban area is distinguished by excessively rocky soil, you need to make your choice in favor of a device with a fishing line, since the metal knife can be damaged. And an uneven and twisted knife can provoke a skew or damage to the gearbox.

If the site is not often looked after, there are a lot of weeds, weeds, as well as shoots of young trees, a grass trimmer with a metal knife will allow you to get rid of them in the blink of an eye.

EUROtools is a good tool in good hands!

When is the use of knives relevant?

When using brushcutters in summer cottages, the most popular attachment is the fishing line. It has a low price, is suitable for different trim heads, and is safe to use. The disadvantage of using a fishing line is that it is convenient only for mowing low growth. In other situations, the string will kick in immediately, regardless of whether a gasoline or electric grass trimmer is used. In addition, vegetation is wound around the spindle, which creates significant resistance on the shaft and leads to its breakage. It can also provoke failure of the piston system in petrol cutters or engine burnout in electric trimmers.

Therefore, for mowing tall or hard vegetation, various attachments are used. So, for harvesting high and coarse grass, thin shoots of trees and shrubs, it is better to install and use a disc. This nozzle clogs up much less frequently, which contributes to greater wear resistance of the equipment.

On a note! Due to the fact that the engine of electric trimmers and battery models is less powerful than on petrol cutters, therefore the use of discs is more relevant for petrol mowers.


It is not recommended to put metal knives on electric scythes, since the design features make their use dangerous for the user. This is due to the curved shape of the rod, the absence of stops on the handles, as well as the high rotation speed.

Important! The straight bar ensures safe use of the grass trimmer when the disc hits an obstacle while spinning. In this situation, it bounces back towards the person, so the curved structure can cause injury.

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Plastic knives should be used on gooseneck trimmers for safety reasons. Their purpose is mowing soft grasses, dead wood. Whereas metal discs do an excellent job with tall, dense, hard undergrowth, shrubs, as well as tree shoots.

Features of discs for brushcutters

Knife discs are available in plastic and metal, as well as in various shapes to perform diverse tasks.

  • Two-, three- and four-bladed knives with pronounced blades are used for mowing grass and tree growth. However, they are not suitable for making hay, as they grind the shoots, chopping them several times.
  • Massive four-blade discs are designed not only for clearing the ground from grass, but also for mowing hay. They prevent repeated cutting of the shoots, thus making them suitable for harvesting for the winter.
  • Discs with cutting edges around the perimeter are relevant for beveling reeds and reeds. These knives are very heavy. a necessary quality to cut through thick stems.
  • Professional saw blades for hedge trimmers and brushcutters for cutting small trees and bushes.

Plastic knives are used as an alternative to metal discs. They do not need to be firmly fixed in the head, but they rotate as a result of centrifugal force. The strength of plastic knives is high, so the service life is quite long.

On a note! The advantage of plastic discs is that, hitting an insurmountable obstacle, they bounce off, and repeated contact does not occur.

Sharpening the disc

Regardless of the quality of the disc, over time it becomes dull and begins to chop grass poorly. If the knives are still relatively new, and replacement is impractical, you can sharpen them yourself.

Important! For sharpening, only those discs that are not soldered from hard materials are suitable. Such parts are thrown away, and new ones are acquired instead.

  • disassemble the grass trimmer, remove the knives;
  • carefully inspect the disc. if cracks are found, it is better to replace the part with a new one, since its further operation is unsafe;
  • bent blades can be gently bent with a hammer;
  • given the size of the disc, you need to choose the right file for metal, this will ensure more convenient work;
  • sharpen all upper cutting edges of the discs at an angle of 30 °;
  • reassemble the grass trimmer in reverse order.

To sharpen the disc, you can use a low speed emery machine with a medium grit grinding wheel. With such a tool, the process will move much faster. For safety, you need to wear gloves on your hands, and a protective mask or goggles on your face.

So, for mowing grass on gasoline and electric trimmers, plastic and metal discs of various shapes and with a different set of blades are used. They are selected in accordance with the type of work performed and the size of the cultivated area. If the blades on the mower are dull, it is easy to sharpen them or change them yourself. Despite the simplicity of the procedure, you need to be careful and remember about safety, so as not to injure yourself through negligence or damage the equipment. A more detailed description of replacing the knives in relation to a specific grass trimmer model can be found in the operating instructions or on the manufacturer’s official website. For clarity, the general scheme of the process is shown in the video.

How to Fit the Disc to the Grass Trimmer

Attaching the blade to the grass trimmer is very simple. For this, a complete wrench is used that disconnects the cutting attachment and a pin that blocks the gearbox. The procedure is as follows.

  • First of all, the electric grass trimmer should be disconnected from the mains, the gasoline trimmer should be simply turned off. Disconnect the protective cover and move to the side.
  • Next, you need to align the holes on the gearbox and the shaft in order to insert a pin into them and block the drive.
  • If a spool with line was used, it must be unscrewed clockwise.
  • Then you need to find a nut to twist the knife.
  • The next step is to install the knives. Trimmer owners often wonder which side to put the disc on. This must be done so that the marking with numbers and letters is on top.
  • Then you need to put a boot on top, and above it. a fixing nut, which must be tightened tightly with a wrench.
  • The last step is to install the protective cover.

As you can see, the procedure is very simple and the same for many brands, be it STIHL or Husqvarna equipment.

knife, grass, trimmer

On a note! If the owner of the device wants to replace the disc back on the line, you can install the reel with it in the same way.

Disk selection criteria

You need to choose a plastic or metal knife, taking into account the area of ​​the site that you plan to process, as well as the type of grass trimmer. electric or gasoline. The number of blades will depend on which growth needs to be removed with the tool. You can choose the desired disk shape, the number of blades and the material of manufacture using the device’s operating instructions. Usually it prescribes which cutters are recommended to be used for solving certain tasks.


The number of blades is important when solving diverse tasks. So, for grinding grass, two or three pieces are enough. To harvest hay, it is necessary that there are four to eight blades on the disc. To destroy small shoots of trees and shrubs, instead of blades on the disks, there should be a large number of small teeth.