How To Remove A Knife And Make A New For Your Lawn Mower

How To Remove A Knife And Make A New For Your Lawn Mower

Cutting elements in lawn mowers are important components that need special care. Over time, the blades become unusable. In this case, they should be sharpened or changed. Before removing the knife from the lawn mower, the owner of the site must perform actions that will secure it during operation.

The functions of a knife in a lawn mower

The blade for the lawn mower performs the function of mowing the grass stand. Knives are made of stainless steel. Sharpening a knife affects the execution of work. A sharp tool evenly cuts the plants. Dumb. Leaves a fringe on them, that is, a cut of each blade of grass is obtained cut perpendicular to the surface into several parts. This happens if you tear the grass with your hands. As a result, the grass is cut neatly and evenly, the next day the cut is tightened. Such a lawn looks attractive and bright. In the second case, the area in front of the house is a dirty green color. Dissected sections are tightened only after 10-18 days.

Lawn mower knife

Note! An additional function of the knife in the lawn mower is to create an air stream during rotation, due to which the plants are transferred to the grass catcher. Blades often have several special serifs for this.

Sharpening the knife rotary lawn mowers

Rotary devices include:

Gasoline mowers;Electronic lawn mowers. Wire and battery.

In their equipment, two-bladed knives are mainly used, less often a knife with 4 blades. The sharpening technique is the same for all types, and does not have any differences.

To do the job you need:

Work gloves;Spanner or socket wrench of the corresponding size;A set of rattles, an abrasive whetstone, or an electronic tool-grinding tool.

Before sharpening the mower knife, you need to perform several preparatory operations:

Prepare the lawnmower to remove the knife. In particular, owners of gasoline models of lawn mowers need to take a close look at this step. It may be necessary to drain the fuel, oil;

Reasons for Removing a Knife

Among the common reasons for removing or replacing a cutting element are as follows:

  • Knife has no edge;
  • The element bent and deformed;
  • Chips and cracks are visible on the knife;
  • The blade has been thinned and thinned.

When the knife becomes dull, bent, or deformed, the lawn after the mowing looks untidy. Competent sharpening will fix 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 are blunt faster, then sharpen them more often.

Knife sharpener

If chips, cracks are visible on the blades, or it has sharpened and become thin, then in this case a replacement is necessary. Sharpening such a tool makes no sense. 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 may also cause engine damage. Changing an element is allowed for a similar model. The characteristics of the knife are indicated in the instructions.

Adapter do-it-yourself mower knife

Lawn mower knife adapter MATRIX Turbo 50 do it yourself. After the destruction of the unusual knife adapter MATRIX.

Knife removal


An independent process for the partial dismantling of a vegetation shearing unit begins with preparatory work. 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 board that will help fix the knife. The electrical appliance is unplugged. At gasoline, fuel is drained and the spark plug is turned off to exclude the possibility of sudden contact. Regardless of the type of machine, the owner must unscrew the grass catcher.

Important! Before turning the mower upside down or upside down, inspect it and prevent gas or oil leakage. The oil in the crankcase is best drained as well. Otherwise, if a leak occurs, it will be problematic to start the unit.

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

Preparing to remove the knife

The mower can be equipped with:

  1. A single two-blade knife of various shapes;
  2. With two knives;
  3. Four-blade blades;
  4. Compound cutting design.

In the first case, one knife is used in the form of a small strip. Its length will be similar to that indicated in the characteristics of the device under paragraph width of the cutting mowing. Usually it is 30-50 cm.

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

On a note! Another version of the cutting system is 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 the additional function of mulching the lawn. Plants from the grass tank fall onto the upper blades. The sharp edges carefully crumble the greens, which after the procedure covers the ground of the lawn and turns into mulch.

How to remove a knife from a lawn mower

Step-by-step process

  1. Before you remove the knife from the lawn mower, it is fixed with a strong board or log, rested in the ground. It is necessary that the knife, when removed, not move. However, some people neglect this safety measure and simply hold the cutting insert by hand.
  2. Take a L-shaped socket wrench or a ring tool, perfect in size. It is not recommended to use pliers. This fitting and assembly item easily spoils the edges of the bolts.
  3. Typically, the cutting unit is mounted with one large bolt located in the middle. Modern models have several fasteners. As a result, you will have to unscrew them all.
  4. Bolts most often have right-hand threads. Therefore, to unscrew the bolt, the key is turned counterclockwise. In order to tighten it back, it is done the other way around, that is, they tighten the bolt clockwise.
  5. It happens that over time, a threaded pair sticks, rusts, and it becomes problematic to unscrew the bolt. In this case, special greases called liquid keys are used.
  6. If the removal was successful, and all the fasteners are intact, then the bolts, nuts, washers are removed into the box for safety. Perhaps these compounds will have to be reused.

Additional Information. Before you remove the knife, you must remember its position. Most often, the knives are pointed counterclockwise, and the rotation of the element occurs in this way. However, the tip is not suitable for all models. Therefore, the position of the element should be paid attention to. It is in the same position that you will have to put a new knife or screw the old one after sharpening.

Adapter lawn mower knife Matrix turbo

Unfortunately, Matrix-direct company has finished supporting this product. In the service centers located in the list.

Turn the mower over to access the cutting tool;Fix the knife with a wooden block;Using the right tool, usually with a socket wrench or a spanner, unscrew the attachment points of the knife;Take off the knife itself.

After cleaning the knife from adhering weed, dirt, you can proceed directly to sharpening.

To sharpen the knife of the lawn mower, you will need a stable base. A table or a workbench, on the surface of which you can comfortably position and fix the knife for final sharpening. A balanced option. If you have the opportunity to fix the knife in a vice.

When performing work, note that the working part of the knife is hardened, you should try so that the impact on the blade is minimal and maintain the angle of sharpening lawn mower knife.

If the working parts of the knife have no damage. Burrs, chipping, then you can limit yourself to editing the blade. Why you can use an abrasive bar or a file with a diamond coating. To remove a large amount of metal is not required, and you can do with a “thin” tool.

If the knife blades are damaged, before sharpening, they must be removed with a rough file, on an emery wheel or with an electric tool with an abrasive nozzle.

If you are doing the work with a file or an abrasive bar, then sharpening is done from the center of the knife to the edge. The movement of the instrument is “away from you”. After completing the work, it is necessary to check whether the balancing of the knife of the lawn mower has changed.

The sharpened knife can be installed on the lawn mower and begin mowing the lawn.

Cleaning the knife before sharpening

Before sharpening the knife, it is thoroughly cleaned. On steel strips plant juice and small particles of grass accumulate. At the same time, the juice hardens over time and turns into a hard crust. It’s not worth washing the blades; it’s best to pick up a sharp metal scraper in the garage or use a tint brush.

It is not necessary to polish the cutting element of the machine to a shine, the main thing is to remove adhering waste. After that, it is necessary to improve the knife by straightening it and removing all irregularities. Bumps arise due to solid debris and stones falling onto the blades. The correct option in this case is to work with a hammer. Using this tool and a flat working surface on which the knife is placed, all local curvatures can be fixed.

Cleaning the knife before sharpening

Experts advise starting to align the blade from the edge, gradually moving to the middle part. As a result, the steel strip should become as flat as possible. Only in this case, it will be able to fulfill its function, creating an air stream that transfers grass to the tank to collect plant debris.

Sharpening the knife of a spindle mower

Drum (spindle) lawn mowers are equipped with a knife block. A formed drum, in which several curved blades and a fixed straight knife are installed. It may seem that it is very difficult to sharpen such a knife, but it is not. You don’t even have to remove the spindle.

To sharpen the spindle knife you will need abrasive. Sandpaper, preferably waterproof.

From a sheet of paper, it is necessary to cut a strip in width greater than the width of the fixed knife by 1-2 mm and stick it on the fixed knife of the lawn mower using double-sided tape, with the abrasive side up.

Then bring the knife drive into action. Hand-held lawn mower. Ride on a flat hard surface several times, if you have an electric drum mower then connect it to the network, turn it on and let it run for a short time, just 1 minute is enough.

Before using the mower, be sure to remove the sandpaper from the fixed knife.

As you can see, sharpening a knife of any lawn mower is not so difficult and every owner of this type of garden equipment can do this job.


Sharpening of cutting elements is organized as necessary. Many people ask: “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 blades.

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


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

During operation, the curvature of the knife and roughness are removed. It is important to maintain the factory sharpening angles and descent. Both sides (blades) grind evenly. The sharpener is held in the same position. An imbalance must not be allowed in which the coordinated operation of the blades is not achieved. Such a problem will lead to operational wear of the assembly units (bearings).

After the main sharpening, it is necessary to correct the edges. This is done in order to remove the smallest breaks. It is best to use sandpaper with a grain of 800 grit. Editing consists in a slight shift of the paper along the plane of the descents.

Note! Instead of a file, you can use the grinding bar. Before the procedure, it is soaked in soap and water for a quarter of an hour. During operation, it is also allowed to slightly moisten the instrument.

Machine tool

The machine will help to cope with work quickly and without putting much effort. The main thing in this matter is not to achieve too sharp edges. If you sharpen them as thin as a razor, then the risk of chipping and breaking is great.

Sharpening on the machine

During operation, it is important to adhere to the correct angle and remove metal from the blades in the same amount. The machine does not eliminate edits by sandpaper.


Before you install the knife on garden equipment, a check for balancing is performed. It aims to find out if the blades of the knife have the same weight. To do this, a sharp strip is put on the pencil with a central hole. The shoulders should be evenly balanced and have the same weight. If one of the sides pulls down, then it is again a little grind.

Knife Installation Rules

After the knife is sharpened, it should be put back. Installation of cutting elements is not very difficult. The main thing. Follow the rules:

  • Determine what position the knife used to be in.
  • In the same position, fasten it with the new or old bolt, washer and nut.
  • Do not overtighten the nuts. This will lead to deformation of the cutting device.
  • During work, you should wear thick gloves on your hands. It is important to remember that updated blades are sharp.
  • Once the mower is on the ground in its normal position, turning it on immediately is not recommended. It is necessary to wait an hour for oil from the walls of the crankcase.

Even the novice gardener can figure out the tricks to remove the cutting element from the mower. However, when sharpening yourself, you should be extremely careful so as not to get injured or remove too much metal by thinning the knife.