Do I Need To Sharpen The Trimmer Knife

Taking out descents

If the knife has not been sharpened for a long time, chipped chips are likely to appear on it. You need to get rid of them by bringing out the edge of the blade at a uniform angle along the entire length of the cutting section.

Please note that there may be several edges on each side, in which case the mower will have several cutting planes.

need, sharpen, trimmer, knife

Lawn mower blades are sharpened on one side, the slope of which is usually directed upwards. To bring the descent to the desired angle, you should use an electric sharpener with a carborundum stone, and in the absence of such a fine file

It is very important to remove metal evenly from both blades. Therefore, keep the same pressure and at least approximately count the number of passes of the sharpener

Small deviations of the sharpening angle are not critical, however, the smoother the slopes are brought out, the longer the knife resource will be. When shaping the blade, it always moves onto the grain to avoid the formation of large burrs and flakes. Do not use an angle grinder for preliminary sharpening. overheating can degrade the quality of the metal. However, it is possible to mount a flap disc or a sanding pad on an angle grinder.


Sharpening of cutting elements is organized as required. Many people ask the question: “Does a new knife need sharpening?” The answer is no. These elements are sharpened at the factory. After purchasing garden equipment, it can be used without additional work on removing and sharpening the blades.

There are two ways to sharpen the cutting element of a lawn mower:

  • File;
  • Machine tool.

Reasons for removing the knife

Lawn mower engine

Common reasons for removing or replacing a cutting element are as follows:

  • The knife is dull;
  • The element is bent and deformed;
  • Chips and cracks are visible on the knife;
  • The blade has worn off and thinned.

When the knife is dull, bent or deformed, the lawn looks unkempt after mowing. Competent sharpening will correct the situation.

Professionals advise to carry out the procedure once a year. It is better to do this in the spring, before starting work. If the cutting elements become blunt faster, then sharpen them more often.

Knife sharpener

If chips, cracks are visible on the blades, or it has sharply worn off and become thin, then replacement is necessary in this case. There is no point in sharpening such a tool. In addition, the blade can break at any time and fly out from under the machine body, injuring people or animals that are nearby. Such a device can also damage the engine. It is allowed to change an element to a similar model. The characteristics of the knife are indicated in the instructions.

Step by step process

  • Before removing the knife from the mower, fix it with a sturdy board or log resting on the ground. It is necessary that the knife does not move when it is removed. However, some neglect this safety measure and simply hold the insert with their hand.
  • An L-shaped socket wrench or box tool is taken, ideally suited to size. The use of pliers is not recommended. This fitting and assembly tool easily spoils the edges of the bolts.
  • Usually the cutting unit is secured with one large bolt located in the middle. Modern models have several fasteners. As a result, you will have to unscrew them all.
  • Bolts are most often right-handed. Therefore, to unscrew the bolt, turn the key counterclockwise. In order to screw it back, it is done the other way around, that is, tighten the bolt clockwise.
  • It happens that over time, the threaded pair sticks, rusts, and it becomes problematic to unscrew the bolt. In this case, special lubricants are used, called liquid keys.
  • If the removal was successful, and all fasteners are intact, then the bolts, nuts, washers are removed into the box for safety. These connections may have to be reused.

Additional Information. Before removing the knife, you need to remember its position. Most often, knives are placed with a tip counterclockwise, and the rotation of the element occurs in this way. However, this advice is not suitable for all models.

Therefore, attention should be paid to the position of the element. It is in the same position that you will have to put a new knife or screw the old one after sharpening


An independent process of partial disassembly of the vegetation shearing unit begins with preparatory work. It is necessary to observe safety measures and work with gloves. It is necessary to prepare a key in order to unscrew the mount, as well as a small plate that will help fix the knife. The electrical appliance is disconnected from the network. At gasoline, the fuel is drained and the spark plug is turned off to exclude the possibility of a sudden contact. Regardless of the type of machine, the owner must unscrew the grass catcher.

Important! Before turning the mower on its side or upside down, inspect it to ensure that there is no gasoline or oil leakage. It is best to drain the oil in the crankcase.

Otherwise, if a leak occurs, it will be problematic to start the unit.

You can also not turn the mower, but simply place it on a frame or two chairs that simulate a lift. After that, the person approaches the device from below.

Preparing to remove the knife

The mower can be equipped with:

  • A single two-bladed knife of different shapes;
  • Two knives;
  • Blades with four blades;
  • Composite cutting structure.

In the first case, one knife is used in the form of a small strip. Its length will be the same as that indicated in the characteristics of the device under the heading width of cut. Usually it is 30-50 cm.

In the second case, two knives are used, which are attached at an angle of 180 degrees relative to each other.

On a note! Another cutting system option is the four blade blades. They are connected to each other by a common base or not.

In the latter case, we are talking about several knives located at different heights. Such a nozzle in the form of an upper blade is equipped with modern models that have an additional function of mulching the lawn. Plants from the grass tank fall onto the upper blades. Sharp edges carefully crumble the greenery, which after the procedure covers the ground of the lawn and turns into mulch.

How to remove a knife from a lawn mower


In the first case, work is organized if the blades are in relatively good condition and are only slightly dull. Usually this sharpening is used if the owner sharpens the cutting elements of his garden tools several times per season. If this is the case, then it will be enough to walk along the edges with a file and correct them.

During work, the curvature of the knife, roughness

It is important to maintain the factory-cut angles and descent. Both sides (blades) grind off evenly

The sharpener is kept in the same position. Imbalance must not be allowed, in which case the well-coordinated work of the blades cannot be achieved. Such a problem will lead to operational wear of assembly units (bearings).

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After the main sharpening, it is necessary to edit the edges. This is done in order to remove the smallest breakages. It is best to use 800 grit sandpaper. Editing consists in slightly shifting the paper along the plane of the descents.

Note! Instead of a file, you can use a sanding stone. Before the procedure, it is soaked in water and soap for a quarter of an hour.

During work, it is also allowed to slightly moisten the tool.

Balancing the knife

After sharpening the edges using any of the methods described, you need to check the balance of the knife. Balance means the same weight of the halves of the product. Insert a pin, nail, screwdriver or any round bar into the hole for fastening. Raise to a low height. If the knife remains strictly horizontal, everything is in order with the balance. When tilted to one side, the balance is disturbed, you need to restore it. Recovery can be quite simple. On the downward side, you need to remove some metal in the same way as you did the sharpening. The metal needs to be removed little by little, periodically checking the balance.

Machine tool

The machine will help you get the job done quickly and without much effort. The main thing in this business is not to achieve too sharp edges. If you sharpen them as thin as a razor, then there is a great risk of chipping and breaking.

Sharpening on the machine

During operation, it is important to keep the correct angle and remove the metal from the blades in the same amount. The machine does not eliminate sanding edges

How often do you need to sharpen knives?

The frequency of sharpening knives primarily depends on how often the grinder is used, how many products it scrolls. If used every few days, the knives will be sharp for about two months. Of course, initially new blades will last roughly twice as long. However, then, regardless of the quality, they will be blunt. Therefore, they will definitely need sharpening.

Remember! An excellently sharpened cutting tool saves time using the device, if it is of a manual type, then your strength, and if it is electric, it will consume electricity.

Determining when it’s time to sharpen your knives is pretty easy. First, the meat will be much harder to pass through the wire rack. Secondly, you will hear how the screws are idling during operation. All this suggests that it is time to sharpen the knives. To do this, you need to disassemble the grinder, rinse it thoroughly and dry it. When the device is dry, you can start sharpening the knives. For the sander to work even better, it is recommended to sharpen the grille immediately. If a surface grinder is available, it is easiest to use it. Otherwise, you can consider other sharpening methods.

Sharpening with a grinding wheel

Abrasive wheels for sharpening knives and grinder grates

The grille is sharpened in the same way. Only now it is put into place, and the abrasive wheel replaces the knife. The difference lies in the fact that when sharpening the grille, the handle of the grinder can be rotated both clockwise and counterclockwise.

Advice! If you use these two sharpening methods at once, you can achieve the maximum effect. To do this, you first need to grind the knives and grate with a grinding wheel, and then use sandpaper to smooth out the parts for a perfect shine. In this case, it is better to use P400 grit sandpaper.

Leveling the surface of the lattice

This procedure will help eliminate several problems at once. Sharpening the grate will allow the knife to fit closer to it. In addition, when leveling the surface, the through holes sharpen, as a result, the sander begins to work much more efficiently.

Grill processing is carried out in much the same way as knife sharpening.

  • Sandpaper with the P120 marking is taken, moistened with water and laid on a flat surface.
  • The grille is sanded with sandpaper. The part is pressed against the abrasive surface and ground in a circular motion.
  • In order not to overdo it with sharpening, it is recommended to regularly check the surface to be treated.
  • Then perform this procedure using sandpaper with a smaller fraction.
  • To make the grille last longer, it is recommended to process it on both sides.

After that, all that remains is to assemble the grinder. If everything is done correctly, then the knife after sharpening will perfectly cut the meat, and not wind it. The updated grille will help him with this. However, it is not always possible to restore the cutting edges with the help of only sandpaper. If the parts are used for too long, then they can simply wear out, cracks and dents appear on them. In this case, it is necessary to resort to other sharpening methods. Experienced experts recommend using a grinding wheel or sharpener.

How to sharpen a knife for a sander with your own hands

Almost every home has an electric assistant that will quickly grind meat into minced meat of any consistency, help squeeze juice, prepare original cookies or homemade noodles, pasta, and some craftsmen make meat delicacies. During operation, there comes a moment when the question arises of how to properly sharpen a knife for a grinder. What needs to be done for this. we will tell you in our article.

Using sandpaper

Sandpaper will help you quickly and easily sharpen the sander blade and grate surface. This will require:

  • several sheets of sandpaper with varying degrees of grit (it is recommended to use P120, P150 and P180);
  • for sharpening parts, it is necessary to prepare a flat and even surface (you can use ceramic tiles or a table surface);
  • container with water.

Knife sharpening

If the knife has been used for a long time, then it must be sharpened. This will improve the performance of the sander. This procedure should be performed sequentially.

  • First, a sheet of sandpaper with the largest grain size is taken. It is moistened with water and laid on a flat surface.
  • The knife is pressed against the surface of the sandpaper with the cutting side.
  • After that, the part is driven in a circular motion on sandpaper. Check the condition of the cutting surfaces periodically.
  • If done correctly, the knife should have a smooth, shiny surface. Do not worry about small scratches. they appear as a result of the action of an abrasive.
  • To make the cutting surfaces smooth, the knife is ground in the same way using P150, P180 sandpaper. This will get rid of all scratches.

Work rules

Before you sharpen the knives for a grinder yourself at home, you need to study their principle of operation, otherwise it will be difficult to achieve a positive result. A movable cutting tool always works in tandem with a fixed grid, which has holes along the entire plane, and they need to be sharpened together. This part rotates together with the auger and four blades begin to grind the product, which, under pressure, penetrates through the holes. In this way, a difference in grinding is achieved, since several grate options are used: with small or larger perforations.

When sharpening, you need to pay attention to each edge of the blades so that they have a sharp edge of the cutting edge.

First, you need to prepare all the necessary materials in order to perform the entire process with high quality and comply with the basic rules.

  • Check the surface on which you will sharpen the knives with a thick metal ruler. attach with the end and make sure there is no gap. Put the paper or circle on the table, fix it firmly. It is better to put a piece of plexiglass under the sandpaper for better horizontality.
  • At the beginning of the work, lubricate the blades and the polished surface of the grate with sunflower oil and leave for a few minutes. The surfaces to be sharpened should also be lubricated for better contact and the formation of a kind of abrasive paste that protects the knives from small scratches. When sharpening on a special water grinding wheel, moisten it with water, not oil.
  • After sharpening a four-blade knife, the grating must also be sharpened, the edges of its perforations also wear out during operation.
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That’s all the recommendations on how to sharpen a knife and grinder grill at home. In the instructions for each model, different manufacturers call them movable or stationary cutting tools.

From two

Double-sided sharpening saves a considerable amount of time, because to return the sharpness to a ceramic cleaver, you need to devote much more time and diligence than for metal products.

The easiest way is to sharpen the knife from both sides in an automatic sharpener. In this case, it is enough just to control the applied efforts and not to overdo it.

If you want to experience all the advantages of a ceramic knife, you should take care of timely and high-quality sharpening.

If you do not have an automatic device at hand, you can use manual devices, for example, a musat or a sharpening stone. In this case, the sharpening of the double-sided knife turns into a combination of two separate single-sided.

Chipped pieces of the knife will affect the cutting process and also ruin the appearance of the knife.

To achieve the best result, it is recommended to sharpen in two stages. the main one with a coarser sharpening stone and the finishing one with a fine abrasive.

Special whetstone

Essentially the same sharpener, but in the form of a rectangular stone and most often with two sides of different grain sizes. The harder side is used for pre-sharpening and working with coarse notches, if any.

The sharpening stone will return the knife to its original sharpness.

The second side is responsible for finishing the cutting surface and bringing it to the sharpest possible state.

Note! Before starting sharpening, it is recommended to soak such a stone in water for 30-40 minutes in order to reduce the friction of the ceramics on the surface of the sharpening bar.

How to sharpen a ceramic knife

Sharpening of a ceramic knife is most often done with the following devices:

Each of the proposed methods can bring both benefits and harm to the ceramic cutter. The main thing that you should not forget is that the surface material is rather fragile, so you should not put unnecessary efforts when carrying out such work.

One side

The very first Japanese ceramic knives had only one side. Their main purpose was to finely chop soft foods and fish. Later, double-sided models appeared in the range.

A knife falling off a table or shelf will inevitably damage it.

In order for a ceramic knife to serve for a long time, you need to operate it.

The main and most important rule that must be adhered to is not to exert too much force on the blade. Also, when sharpening, it is necessary to ensure that the ceramic surface does not heat up too much, this can cause it to chip.

The problem of how to sharpen a ceramic knife can be dealt with in different ways.

Sharpening options and rules

Depending on the type of blade, certain sharpening rules must be followed. There are some nuances when working with single and double-sided blades. We will consider them further.

The biggest disadvantage of ceramic models is fragility.

Advantages and disadvantages of a ceramic knife

The main advantages of ceramic knives include:

  • high severity;
  • resistance to the absorption of foreign odors and moisture;
  • lack of oxidative processes when interacting with products.

It is for the absence of any interaction with products that ceramic knives are so highly valued, especially among allergy sufferers.

Such a product is easy to cut and shred products.

But at the same time, ceramics has several disadvantages:

  • High fragility. One wrong movement, working with too large bones inside vegetables or fruits, or trying to cut too hard material can result in the blade chipping.
  • The ability to sharpen the blade only with special diamond compounds.

Knives require correct and careful use.

The rather high softness of the material makes it not such a versatile tool as metal, but with proper handling, you can achieve an excellent result without any change in the original taste and aroma of the products, which is greatly sinned by the metal brothers.

Diamond paste

This paste contains finely dispersed diamond grit. For the main sharpening, the material is not used, but as a final step to give the surface the highest sharpness, it is perfect.

You can sharpen a ceramic knife at home using diamond paste.

The paste is applied to the surface of any smooth material (most often paper or leather is used, the fabric easily absorbs the paste and is not recommended for use) and the blade is finished.

Note! When carrying out such an operation, you must be extremely careful to prevent skin cuts and other damage.

Hand sharpener

Hand sharpener. flat surface with diamond grit and handle.

Typically, this blade sharpener has slots. We insert the blade into them and begin to sharpen with smooth movements, parallel to the cutting edge. To make sure of the quality of sharpening, you can try using a knife on any product, best of all on a soft fruit or vegetable.

Clipper Blade Sharpening

Before buying a tool, you need to find out what type of sharpening is needed for a particular type.

And if the result suits you, the sharpening is considered complete.

What knives to put on an electric and lawn mower

Before buying and putting a knife on a lawn mower, let’s 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.

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

  • Lawn mowers type;
  • Mowing areas.

For safety reasons, manufacturers do not recommend putting steel knives on electric trimmers. Almost all electric and battery powered lawn mowers are equipped with plastic blades. Depending on the manufacturer, they can be of a solid disc-shaped structure, with several blades or in the form of a special mowing head providing for the installation of removable plastic blades.

Straight bar for petrol trimmer and curved for electric

To put a metal knife on an electric 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 scythe is thrown to the feet.
  • The high torque we mentioned above, in the event of a metal blade hitting a hard object, transfers a large load to the trimmer flex shaft and its 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 only plastic knives on trimmers with electric motors. When hitting an obstacle, the blades are destroyed, thereby protecting the legs of the mower 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 for a firm grip. D-shaped handles of lawn mowers are equipped with a stopper that rests against the mower’s leg, 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 extinguish part of the impact.
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Thus, petrol 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 disc blades supplied to the trimmer in no way affects 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 plan on making hay, it is best to use more bladed knives on the mower. Note the discs with eight teeth or discs with four large blades and four additional ones. Two and three bladed knives will chop the grass hard.

Why you need to put the knife on the trimmer

A trimmer with a knife installed on it is most convenient to use for more comfortable mowing of tall and coarse grass in the country. The line on the lawn mower in such cases does not cope. Thin breaks 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 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 the 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.

How to put the knife on the trimmer

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

How to put a knife on the trimmer

Putting the knife on the 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 setting the knife to the 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;
  • We unscrew the spool with line or the fastening nut holding the boot (if the trimmer has not been used yet) from the hub clockwise;
  • 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.

Trimmer knife: when to use and which one to choose?

Using a trimmer in summer cottages and household plots greatly simplifies and speeds up the mowing of grass. However, it is important to choose the right “consumable” for the electric petrol trimmer. Simply put, what exactly you will be mowing the grass: with a cord (special trimmer line) or with a knife. Both the fishing line and the knife are equally well suited for mowing grass in hard-to-reach places, but in which cases the knife is more effective?

When to use a trimmer knife?

Most often, it is the fishing line that is used, since it is safer to use and provides almost the same result when mowing grass. But if you have to mow tall enough grass, you will certainly encounter the fact that long stems will wrap around a spool or spindle where the trimmer head is attached. To avoid this, it is recommended to use a cutter knife for the trimmer.

The cutter will also be more effective if you need to cut dry grass, shrubs, burdocks, nettles or hogweed. The only thing a knife can be afraid of is collisions with a stone.

The trimmer knife can be made of either plastic or metal. Each trimmer model is initially supplied (or offered by the manufacturer) its own type of knife. This is due to the shape of the trimmer bar and is done in order to maximize the safety of the user. Therefore, you do not need to take a metal knife if your trimmer model involves the use of a plastic one. Even if you are assured of the versatility of the knife.

A trimmer knife can look like a special mowing (trimmer) head with schematic plastic blades, or be a one-piece design, for example, a circular blade with a different number of blades (as a rule, such models are made of metal).

A trimmer with a metal knife will help to get rid of not only grass, but also bushes or young trees. You can also trim raspberries and currants with a trimmer.

Basic safety rules when using metal trimmer knives

The metal trimmer blade is only suitable for straight-bar units. This is due to the design features of the tool. When, when mowing grass (bushes, thin trees), the disc hits an obstacle (usually a stone), it most often bounces back. towards the user. For straight bar trimmers, the distance from the head to the feet of a person is quite safe.

Also, such trimmers are held by the user using T (U) or J-shaped handles, and if the handle is D (O).shaped, then a special limit bar is included with it, which rests on the leg and allows it to get closer to the cutting tool.

If your knife bent when hitting an obstacle, don’t rush to replace it. You can level it yourself with a hammer. The flexibility of the knives is designed to reduce stress on the engine and transmission.

Is the shape of the knife blades important??

The experience of professionals and ordinary users has shown that the shape of the blade matters only if you are cutting grass for harvesting for the winter, such as hay for animals, since three and four-blade knives chop the grass too much. But the quality and speed of the bevel with different blades do not differ significantly.

The most popular model of the trimmer knife is the round shape with eight teeth around the circumference. Also, its variety is often used: with four large teeth and small ones between them.

And for bevelling shrubs (raspberries, currants) and thin young trees, an ordinary disc-shaped knife with many teeth is most often used. It can be installed on any trimmer, even with low power, and effectively treat the area.