Installing a Knife on a Trimmer Farm

For a comfortable mowing of vegetation in a personal plot, the optimal choice of the characteristics of the trimmer will not be enough. Both for the electric trimmer and for gasoline lawn mowers, it is necessary to choose the right cutting tool. As such, a trimmer line (cord) or a special knife is used.

The fundamental type of vegetation when choosing what to mow is. For the convenience of the user, the user can choose the type of cord, the type of trimmer head, the method of refueling the cord into it, and select a knife of a certain shape. Therefore, you should familiarize yourself with these characteristics in more detail.


The classic cutting tool for all types of tools is a special trimmer line or cord, also sometimes called a string. Its thickness (diameter) ranges from 1.2 to 4 mm. For each trimmer, the maximum cord thickness is indicated, which can be used without overheating of the engine and accelerated wear of the bushings.

In addition to differences in thickness, the trimmer cord also has a different cross-sectional shape: a circle, a polygon (from a tri-to a hexagon), an asterisk, rounded protrusions, etc. In addition, it can twist along the longitudinal axis in the form of a twisted square or spiral round string, have various notches and grooves. All these tricks are designed to increase efficiency when mowing vegetation.

The most versatile is the trimmer line with a round cross section, which can be used to mow both fresh grass and dead wood. In addition to such a universal cord, manufacturers also produce more specialized fishing line.

Taking into account the fact that the smaller the contact area of ​​the cord with the stem, the greater the force of its impact, a figured cord appeared with a cross section in the form of a polygon or an asterisk with sharp corners. Later, for strength, particles of aluminum began to be added to it.

A square fishing line with a thickness of 2.4 mm will make it easy to cope with thickets of dry weeds and even stalks of raspberry bushes. But the asterisk, on the contrary, is designed for gentle mowing of fresh grass. Due to the profile, it cuts vegetation cleaner, the grass leaves faster after shearing and does not dry out as often as after applying a round fishing line.

A round fishing line in the form of a spiral is considered low noise, but this parameter is relevant only for electric trimmers, since the sound of a running gasoline engine blocks the whistle from any fishing line.

When using a trimmer with a shaped section, its thickness should be taken less than the maximum for this trimmer. this will avoid problems with the supply of fishing line from the mowing head. Fill such a cord in a coil with gloves on.

The trimmer fishing line has a variety of colors and in most cases it does not have a functional value. But with some manufacturers, the color determines the diameter of the cord (for example, Stihl) or the properties of the material used (for example, Oregon).

For the manufacture of trimmer fishing line use nylon (polyamide) or polypropylene. Leading manufacturers for the manufacture of cords used PP6 polypropylene. In the line of Chinese origin to reduce the cost, various low-quality polyethylene is often added. But in any case, after prolonged storage, the polypropylene cord becomes brittle. To increase elasticity, such a fishing line should be soaked in water for half an hour before use.

In no case should you use a thin wire or stranded cable as a trimmer cord. Thinking in this case about the strength and wear resistance of the fishing line, they forget that the trimmer string is specially made in such a way as to break off to soften the dynamic impact on the transmission and the tool engine. In addition, the cable and wire still break off. At the same time, broken pieces dispersed to high speed easily pierce leather shoes.


The trimmer head, often also called the mowing head, is a specially designed coil, inside which a cord of a certain length is placed. A piece of cord of 8-15 m is wound onto the inner spool, the ends of which are pulled out of the reel to the required length as they wear or break off when they encounter an obstacle that is too hard.

As a rule, for different models of trimmers, certain mowing heads are used, which differ in both the internal structure and the method of attachment. For some trimmer heads, special adapters are available that allow the use of such heads on trimmers of various models and from different manufacturers.

Trimmer heads are usually subdivided according to the type of supply of fishing line to manual, semi-automatic and automatic. In the former, as is clear from the name itself, the fishing line is fed from the head manually. To do this, you will have to stop working, turn off the trimmer and manually extend the ends of the cord.

For the second, it is enough to touch the mower coil on the ground. In this case, by pressing a special button upon impact, the anchor mechanism is released and the cord is fed due to centrifugal force. The fishing line is lengthened when the trimmer is working.

In the third option, to extend the cutting cord, you just need to reduce the engine speed, then with a subsequent increase in speed, the trimmer line is automatically fed.

Video: Installing a Knife on a Trimmer Farm

As follows from the above description, the mowing reel with manual feed of the cord is the most inconvenient, and the mowing head with automatic feeding is the most optimal. However, it did not win much love among users due to the increased consumption of fishing line compared to other types. Therefore, the most popular and sought-after semi-automatic trimmer heads.

Also, different models of trimmer heads differ in the way the line is refueled. They can be quick-loading (for example, Shindaiwa Speed-Feed), when there is no need to disassemble the coil for winding a new portion of the cord, and collapsible.

In the first embodiment, you can not remove the mowing coil from the trimmer. The end of the cord is threaded through both ears in the reel, then the required amount of fishing line is wound and cut off. Or both ends of a pre-cut piece of cord of the required length are threaded into the corresponding holes and wound.

In the second embodiment, to charge a new portion of the cord, the trimmer coil will need to be removed, disassembled and wound the fishing line on the spool inside. Different models of reels differently disassemble and wind the fishing line. But in all cases, the fishing line must be wound in the direction indicated by the arrow on the body (both ends in one direction).

Installing a Knife on a Trimmer Farm

On cheap Chinese mowing heads, the so-called "noun," such an arrow is often missing. Also, on branded models there can be two arrows in different directions (when it is possible to use them on trimmers with different directions of rotation of the head). In this case, the cord must be wound in the direction of rotation of the shaft (that is, the engine must wind it). If the cord is wound in the wrong direction, then when you hit the button on the ground it will fly out too much.

The opposite is also possible. when a semi-automatic mowing head hits the ground, fishing line is not fed. This can be caused by improper winding of the fishing line, or by the fact that after installation on the trimmer they simply forgot to pull the ends of the cord out of the retaining grooves on the spool.

Another nuisance when mowing vegetation with a trimmer cord is sintering of coils inside the coil. This happens because when meeting with a too hard obstacle, the cord is sharply braked. With such jerks, it is drawn in and sticks to the part wound on the spool. As a result, you have to interrupt work, disassemble the coil and tear together the coiled turns of the cord. In some cases, this can be avoided by spraying the fishing line wound on the spool with a silicone spray before installing it in the reel.

Most often, a semi-automatic head of two spring-loaded parts (housing and spools) is used for trimmers. Structurally, the spool can be in two versions. Two-sectional, when each end of the cord is wound into its own section, which reduces its tangling and sintering. Or single-section, when both ends of the fishing line are wound together.

Our craftsmen came up with a simple, cheap and elegant way to turn a single-section spool into a two-section, the essence of which can be understood from the above photos.

To do this, a ring is cut from a strong and thin plastic plate, the inner diameter of which corresponds to the thickness of the spool in the area of ​​winding the line, and the outer one to the diameter of the protrusions. That is, along the spool such a ring should move freely. Then a cutout is made for the cord, the ring is cut, put on a spool and the cut is glued using tape. Now each end of the fishing line can be wound into a section designed for it.

The mowing head with the feed of the prewound cord has two or four opposing openings from which the mowing ends exit. In addition to reels with a portion of the fishing line, there are also trimmer heads with plug-in pieces of fishing line of a fixed length (for example, Oregon Jet-FIT).

In this case, the number of working "mustache" can reach up to twelve. Some users consider this design to be quite convenient, but another part is unhappy because they believe that the cord consumption increases and that it needs to be stopped to replace it. In these heads, as a rule, a fishing line with transverse notches is used.


When mowing with trimmer cord of tall grass, it will be wound on the spindle at the attachment point of the mowing head. How often this will happen, largely depends on the design of the head and the properties of the mowed grass, but this can hardly be completely avoided. The best solution would be mowing not with a cord, but with a trimmer knife specially designed for such cases.

A knife for a trimmer used as a cutting tool can be made of plastic or metal and have a different number of blades (teeth) of various shapes.

On models of trimmers with a curved rod, only plastic knives should be used (for the safety of the mower and commensurate with the capabilities of the flexible shaft). In addition, they often come with electric trimmers.

This can be either a special mowing head with replaceable removable plastic knives, or a one-piece design in the form of a disk knife with a different number of blades. Such trimmer knives have tough vegetation on their teeth (dry grass, burdocks, nettles, etc.).

For processing large areas and mowing not only grass, but also cutting shrubs or even young trees, metal knives are used. The only thing such trimmer knives are “afraid of” is collisions with objects that are too hard for them (for example, stones).

Metal knives can only be used on straight-bar trimmers. They cannot be mounted on a tool with a curved bar. This is primarily due to safety precautions. If, when mowing vegetation, the disk comes across a solid obstacle, then in this case it is thrown back. For straight-bar trimmers, the distance to the user’s feet is significantly further.

Plus, a T (U) or J-shaped handle helps to hold the tool, and a special protruding limiting bar is added to the D (O).shaped handle, which abuts the foot and does not allow the cutting tool to come to it. Curved bar trimmers are usually equipped with a D (O).shaped handle without a limiter.

Secondly, a high-torque metal circular knife creates a large load on the flexible shaft and motor, which leads to quick tool breakage.

As user experience shows, the shape of the blades (triangular, rectangular, etc.) practically does not affect the quality and speed of mowing. But their number becomes important when using a trimmer for harvesting hay. Three or four-pronged knives chop the grass too much when mowing.

The most optimal for haying are considered to be almost round eight-tooth knives or with four large and additional smaller teeth between them. Perforated discs with a large number of teeth are also popular. such a lightweight mill for the trimmer can be installed on low-power tools.

Using a cutter for a trimmer, that is, a circular knife with a large number of teeth, it is possible not only to clean the area from luxurious perennial weeds, raspberries, etc., without problems, but also cut trees with a trunk diameter of several centimeters.