DIY grass trimmer disc


  • metal perforated plate (100 mm x 240 mm)
  • 2 hacksaw blades for metal
  • 4 screws and 4 nuts M5
  • 4 washers and 4 oversized washers

From a safety point of view, hacksaw blades should not be completely hardened.

Everything you need to make a nozzle

The most difficult part in making a nozzle is to symmetrically mark and make holes for the knives and the grass trimmer shaft. That is why a ready-made perforated plate is chosen.

DIY grass trimmer attachment

For many summer residents, a grass trimmer has long become a familiar and almost irreplaceable technique. But it is not always possible to purchase a model that meets all needs. It happens that the grass trimmer copes with fresh young vegetation easily, but there is a desire to clear a place behind the fence or along the driveway, and the tall matured grass turns out to be too tough for the technique.

grass, trimmer, disc

DIY grass trimmer attachment

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We offer the option of self-production of the grass trimmer attachment from simple (almost improvised) means.


First you need to make the base of the nozzle. To do this, cut a square with a side of 100 mm from a metal plate with an angle grinder. You need to mark it in such a way that there is a hole exactly in the center (at the intersection of the diagonals). To do this, measure a distance of 50 mm from the center of the selected hole perpendicular to the short side of the plate and outline the cutting line for cutting.

We mark the base of the nozzle

Cut off the excess and get a square of 100 mm x 100 mm. Now you need to round the corners a little and drill the center hole for the grass trimmer shaft.

Round off corners and drill center hole for grass trimmer shaft

We cut the canvases for metal, measuring 8 cm from each end.We get 4 blanks with ready-made holes.

We cut canvases for metal

These blanks need to be shaped like knives. To do this, we outline the cut line by eye (special accuracy is not required), fasten all 4 blanks together and grind off the excess.

Cut out knives from blanks

As a result, we get knives of the same weight and size, they can be sharpened a little on one side. Now all parts of the homemade grass trimmer attachment are ready, you can start assembling.

Everything is ready for assembly

Put a small washer on the screw and insert it into the corner hole. We put on the knife from above, placing the sharpened side in the direction of rotation of the grass trimmer shaft. This is followed by a large washer and a nut that is not tightened so that the knife rotates freely. In the same way, we attach the other 3 knives.

Fixing the knives

The end of the screw must be riveted so that the nut does not fly off.

The end of the screw must be riveted

The attachment is ready. It is installed with nuts to the ground and fixed in the same way as the three-blade knife that comes with the trimmer. When colliding with a stone, the knives fold and go inside a little.

This idea was suggested by our regular video author Tatiana (Tula region). You can see in more detail the whole process of making such a grass trimmer attachment and find out some of the nuances by watching the video that she prepared.

When working with a trimmer, it is important not to forget about safety, using any attachments, especially homemade ones.

We suggest discussing this idea in the Комментарии и мнения владельцев to the publication. Share your thoughts with us, and also tell us about your good solutions.

Without accepting any of the sides of this sharp (literally and figuratively) discussion, let me show you one of the latest models of brushcutters from the German company Robert Bosch. It provides for both a deflecting knife and an arcuate bracket, which excludes the “striking” of the knife on objects not foreseen by mowing. I show the general view of the brushcutter and the knife itself, in two positions. General view of brushcutters

Knife in a deflected state

Folded knife

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Good evening everyone! Exactly three years have passed since the discussion of the “acute” problem for the grass trimmer. Over the past 1000 days, a clear picture has emerged: “Glory to the author, the craftsman, who conducts an experiment on himself to reach the yield point of the metal from which these knives are made. He has every right to risk his own health. ” Nowadays in stunt films you can often see a frvza. “Do not try to repeat the movie stunts that were performed by professional stuntmen.” The very first article was supposed to end with approximately the same phrase: “Dear summer residents. This is my personal experiment. If you are not sure of your locksmith’s abilities, please do not repeat it. AND MOST IMPORTANT. I am not responsible for the operation of the tool, made in the footsteps of my articles.” And the last thing. Do I see errors, judging by the photographs, of the execution of this tool. Yes, I see, and a rude one. Look closely at the plate, which is the carrier for the four knives. Look closely at the FAR RIGHT HOLE in the photo.

Alas, the author of this device does not even suspect how the hole for the shaft should be made.

I inform you that the distance from the point of the hole closest to the edge of the plate to the very edge should be NOT LESS than the diameter of the hole itself. Students of mechanics will learn this truth no later than the second year of the institute. What do we see here? A thin isthmus resembling a narrow PEREKOP, making a peninsula out of the Crimea. This is a priori the place that is weak in this design. it experiences the same loads as other knives, but the “digging” there is very thin. Where it is thin, there and I would like to hope, and quite sincerely, that over these three years this isthmus has not undergone loads comparable to the yield strength of this metal, but rather the alloy from which the perforated plate is stamped.

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.

grass, trimmer, disc


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.

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.

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

Rules for replacing knives on the grass trimmer

If the trimmer disc is used regularly, it will need to be removed from time to time and sharpened or replaced with a new one. This part can be made of metal or plastic, have a different number of blades, but the replacement process remains the same. over, this procedure is similar for equipment from different manufacturers, be it Carver or Huter, but slight differences are possible. It is quite simple to change the knife on the trimmer if you follow the safety precautions and know the correct procedure, the description of which can be found in the user manual. The entire replacement process step by step, as well as the method of self-sharpening knives, will be described in this material.


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.

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.

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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.

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.

Diamond blade universal grass trimmer blade

If you have an old diamond blade, don’t just throw it away. It can be used to make a universal blade for a petrol grass trimmer.

Such a self-made disc has a lot of advantages. Firstly, it cuts dry small grass well enough that the line does not take. Secondly, it does an excellent job with very tough grass.

And one of the most significant advantages of such a disc is that it cuts well bushes and trees, the trunks and branches of which do not exceed 12 cm in diameter.A disc of 180 mm at a time cuts up to 60 mm.

The whole secret of the high performance of a homemade blade lies in the shape and number of cutting teeth. Largely due to the special shape of the tooth, the disc does not burrow into the wood, and also does not lose momentum even with a weak trimmer.

The main stages of work

Please note that if you are using a diamond disc for an angle grinder, the first step is to drill a hole in it. The fact is that discs for an angle grinder have a hole diameter of 20-22 mm, and most trimmers have 25.4 mm.

After adjusting the bore hole to size, place the stencil paper over the disc. The stencil itself can be downloaded from the link.

To eliminate the damping slots and holes in the disc, which serve for cooling and dust removal, it will be necessary to reduce the original disc diameter to 180 mm. Next, cut out the paper stencil clearly along the contour.

There is no need to cut a hole in the center. We clean the surface of the disc from rust and dirt, apply stationery glue on it, align the stencil exactly along the mounting hole and press it.

Disc manufacturing process

At the next stage, we cut off the diamond disc with an angle grinder according to the glued stencil. Then, with a cleaning disc, we remove the remnants of the metal, reaching the edge of the stencil.

On the way, the master cuts damping slots in the disc. We process the edges with a petal circle and then remove the stencil.

After that, it will be necessary to separate the teeth. This can be done with ordinary pliers. However, to make the angle the same, the author uses a special layout. Odd teeth need to be bent to the left, even teeth. to the right.

Further, the cutting teeth must be sharpened. The optimum sharpening angle is 15-18 degrees from the center. If the metal is soft, the tips of the teeth must be hardened. To do this, simply heat them red-hot with a gas burner and dip them in engine oil.

Details on how to make a universal disc for a grass trimmer from a diamond disc with your own hands can be seen in the video on our website.