How To Remove The Knife From The Lawn Mower?

Cutting elements in lawn mowers are important components that require special care. Over time, the blades become unusable. In this case, they put sharpening or changing. Before removing the knife from the lawnmower, the landlord must perform actions that will secure it during operation.

The functions of the knife in the lawn mower.

The blade for the mower performs the function of mowing the grass. Knives made from high-quality steel. Sharpening the knife affects the performance of work. A sharp instrument cuts plants smoothly. Blunt. leaves a fringe on them, that is, the cut of each blade of grass turns out to be cut into several parts perpendicular to the surface. It happens if you tear the grass with your hands. As a result, the grass cut neatly and smoothly, the very next day, the cut is delayed. Such a lawn looks attractive and bright. In the second case, the area in front of the house turns a dirty green color. The dissect sections are tightened only in 10-18 days.
Note! Additional function of the knife in the lawn mower. during rotation to create airflow, through which the plants transferred to the collection box. For this, the blades often have several special series.

Reasons for removing the knife.

Common causes for removing or replacing the cutting element include the following:

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

When the knife is blunt, bent or deformed, the lawn looks untidy after shearing. Correct the situation competent sharpening.
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 get blunt faster, then they sharpen them more often.

Knife sharpening

If chisels, cracks are visible on the blades, or it is very shaky and thin, then a replacement is necessary. Sharpening such a tool does not make sense. Also, the blade can break at any time and fly out from under the body of the car, injuring people or animals that are close by. Such a device may also cause engine damage. Change the item is allowed on a similar model. The characteristics of the knife indicate in the instructions.

Knife removal.


An independent process of partial disassembly of the unit for cutting vegetation begins with the preparatory work. You should observe safety precautions and gloves. It is necessary to prepare the key to unscrew the mount, as well as a small plate that will help fix the knife. Electrical appliance disconnected from the network. Gasoline drains from the gasoline, and the spark plug is disconnected to prevent the possibility of immediate contact. Regardless of the type of machine, the owner must unscrew the collection box.
Important! Before turning the mower on its side or upside down, inspect it and avoid leaking gas or oil. It is best to drain the oil in the crankcase too. Otherwise, if a leak occurs, starting the unit will be problematic.
You can also not turn the mower, but put it on a frame or two chairs that mimic the lift. After that, the person is selected to the bottom of the device.
Preparing to remove the knife

The mower can be equipped with:

  1. Single bilobed knife of different shapes;
  2. Two knives;
  3. Blades with four blades;
  4. Composite cutting structure.

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 the item width of cutting mowing. Usually it is 30-50 cm.
In the second case, two knives are used, which mounts at an angle of 180 degrees relative to each other.
On a note! Another option for the cutting system is blades with four blades. They are connected 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 equips modern models that have the additional function of mulching the lawn. On the upper blade get plants from the tank for the grass. The sharp edges carefully chop up the greens, which after the procedure covers the ground of the lawn and turns into mulch.

Step-by-step process.

  1. Before you remove the knife from the lawn mower, it is fixed with a sturdy board or log, rested in the ground. It is necessary that the knife when it is removed does not move. However, some of this security measure neglect and hold the cutting plate with your hand.
  2. An L-shaped socket wrench or a capping tool, ideally suited to the size, is taken. It is not recommended to use pliers. This fitting and assembly object easily spoils the faces of the bolts.
  3. Usually the cutting unit is attached with one large bolt located in the middle. Modern models have several fasteners. As a result, you have to unscrew them all.
  4. Bolts most often have right-handed threads. Therefore, to unscrew the bolt, the key is turned counter-clockwise. To tighten it back, the opposite is done, that is, the bolt is screwed clockwise.
  5. It happens that over time, the threaded pair becomes attached, rust, and it becomes problematic to unscrew the bolt. In this case, special lubricants are used, called liquid keys.
  6. If the removal was successful, and all fastenings are intact, then the bolts, nuts, washers are retracted into the box for safety. It is possible that these compounds will have to be reused.

Additional Information. Before you remove the knife, you must remember its position. Most often, knives are set counter-clockwise, and the element is rotated in this way. However, the advice is not suitable for all models. Therefore, the position of the element should pay attention to. It is in the same position that you have to put a new knife or fasten an old one after sharpening.

Cleaning the knife before sharpening.

Before sharpening the knife, it is thoroughly cleaned. On the steel, stripes accumulate sap of plants and small particles of grass. At the same time, the juice hardens over time and turns into a hard crust. You should not wash the blades. It is best to pick up a sharp metal scraper in the garage or use a brush-brush.
It is not necessary to polish the cutting element of the machine to shine, and the main thing is to remove sticking waste. After that, it is essential to improve the knife, straightening it and removing all the irregularities. Hillocks are caused by solid debris and stones falling on the blades. The correct option, in this case, is to work with a hammer. With this tool and the flat working surface on which the knife is placed, all local curvatures can be corrected.
Experts advise starting to align the blade with the edge, gradually moving to the middle part. As a result, the steel strip should be as flat as possible. Only in this case will it be able to perform its function, creating an airflow that transports grass to the tank for collecting plant residues.


Sharpening cutting elements are organized as needed. Many ask the question: “Does a new knife need sharpening?”. The answer is no. These items are sharpened at the factory. After buying garden equipment, it can be used without additional work on the removal and sharpening of the blades.
Sharpen the cutting element of the lawn mower in two ways:

  • By file.

In the first case, the work is organized if the blades are in relatively good condition and dull only slightly. Usually, such sharpening is used if the owner sharpens the cutting elements of his garden tools several times a season. If this is the case, then it is quite enough to walk along the edges with a file and fix them.
During operation, the knife rounding, roughness are removed. At the same time, it is essential to preserve the angles of factory grinding and lowering. Both sides (blades) grind evenly. The sharpener is kept in the same position. An imbalance should not be allowed in which no well-coordinated operation of the blades is achieved. This problem will lead to operational wear assemblies (bearings).
After the primary sharpening, it is necessary to carry out the editing of edges. It does remove the smallest bummer. It is best to use sandpaper, a grit which is 800 grit. Editing is a slight shift of paper on the plane of the slopes.
Note! Instead of a file, you can use the grinding bar. Before the procedure, it soakes in soap and water for a quarter of an hour. During operation, it is also allowed to dampen the instrument slightly.

  • Machine tool.

The machine will help to cope with the work quickly and without putting 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 high risk of chipping and cracking.
Sharpening on the machine
During operation, it is important to adhere to the correct angle and remove the metal from the blades in the same quantity. The machine does not eliminate the edging of sandpaper.


Before you install the knife on the garden equipment, checks for balancing. It aims to find out whether the blades of the knife have the same weight. A sharp strip puts on the pencil center hole to do this. Shoulders should balance exactly and have the same weight. If one of the sides pulls down, then it is once again a little grind.

Knife installation rules.

After the knife is undercut, it should be put back. Installing cutting elements is not very difficult.

The main thing. follow the rules:

  • Determine what position the knife was in before.
  • Secure it in the same position with a new or old bolt, washer and nut.
  • You can not overtighten the nuts. It will cause the cutter to deform.
  • During work, wear thick gloves. It is important to remember that the updated blades are sharp.
  • After the mower is on the ground in its normal position, it is not recommended to turn it on immediately. It is necessary to wait an hour to glass oil from the crankcase walls.

Even the beginning gardener can deal with the wisdom of removing the cutting element from the lawn mower. However, when self-sharpening should be extremely careful not to get hurt and do not remove too much metal, thinning the knife.