Craftsman Lawnmower Knife Replacement
Lawn mowers are very popular today. They are used to keep the household plot, garden, decorative “field” in proper condition, and their owners often ask quite logical questions regarding how to increase the efficiency of the device and at the same time extend the operating life
The answer to this question is quite simple. To do this, it is necessary to timely check the reliability and degree of sharpening of the knife for the lawn mower, and also, if necessary, change it in time.
Craftsman lawn mowers require special, original knives that can be either straight or curly. Also, in addition to knives, it is necessary to purchase suitable washers and rings, which contribute to the correct operation of the device correctly and allow you to quickly and reliably install the knife in place.
Craftsman Lawn Mower Device
As for the device of the Kraftman lawn mower, it is quite typical for this kind of equipment. The manufacturer made sure that its equipment was ideal for simple and safe use for its intended purpose.
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The device of the lawn mower consists of the following elements:
- Wheel drive handle with control bracket;
- Starter handle for starting;
- Motor with silencer;
- Fuel tank and air filter;
- Grass catcher;
- The system of regulation of the height of cutting the lawn.
Also it is imperative to check the mower for loose fasteners, because its device, if used improperly, can affect the quality of work, as well as interfere with the performance of the main function. And if you have not decided which lawn mower to choose, then we advise you not to hesitate and click here.
The principles of selection and characteristics of the knife
As a rule, the manufacturer always takes care that the basic configuration of its products contains all the necessary equipment to guarantee high-quality operation of the device. Craftsman must have two knives as standard equipment:
- A sharp knife designed to trim the grass. It has wide blades and is unilaterally sharpened. This is necessary for a quality and quick cut of grass at a given height.
- A special knife for mulching. He finely cuts the grass and passes it further to the grass catcher. You will find out how the mulching of a lawn by a lawn mower takes place here.
That’s what 100% never and under no circumstances can be saved, so it’s the choice of knives for a lawn mower. This is due, first of all, to the fact that the highest rotation speed, as well as significant loads caused by the resistance of grass stems, strongly affect the blade blades.
In the case when the stalks of the grass do not cut, but simply break, this can adversely affect the appearance of the lawn and even lead to its illness, or, so-called baldness
Knocks on the knife often violate the entire balancing system of this device, and this, in turn, leads to strong vibration and damage to the bearings. Also the continuation of the chain reaction is often the failure of the bushings of the motor of the lawn mower and its wheels.
The principles of choosing knives:
- Only trusted brands that cooperate with manufacturers of this equipment and guarantee a high class of quality knives should be preferred;
- When choosing, it is necessary to give a report on how, how and where the device will be operated, what loads will be exposed. And only on the basis of these data, it is possible to give preference to certain variations of knives;
- It is imperative to select knives for mowing and for mulching, it is necessary to take into account the specific features of each of them, their shape and type of sharpening.
Features of replacing the knife in the.
Manufacturers and prices
For the instrument to function properly, it must be equipped with the appropriate knives manufactured under the CraftsMan brand. Knives of lawn mowers of different grades necessarily differ in a specific form, which is combined with the shape of the deck and helps to create optimal aerodynamic properties for mowing and assembling grass.
It is important to remember that the sharper the selected knives, the better they will cut grass, and that is a fact. And by clicking here you can learn about lawn mowers for tall grass.
Consider the most popular knife models:
- Craftsman 942-0741. This type of knife is ideal for use in Craftsman self-propelled gas mowers. It performs the function of a cutting element, and thanks to its excellent work, the lawn is given a more beautiful and well-groomed appearance. The knife is made of steel. Its length is 21 ″. The price is about 1200 rubles.
- Craftsman 421825. This knife is used for mowing grass. It is made of especially high impact steel. Its main task is the evenness and accuracy of mowing. It is characterized by a large resource of work and is able to last a very long time. The price is about 1300 rubles.
- Craftsman 5321592-67. This Craftsman brand knife is a great option for the professional use of the mower. The most durable and sharp, withstands shock. The length of the knife is 22 ″. The price is about 1900 rubles.
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To summarize, it’s worth noting that the Craftsman lawnmower knives offer superior quality and reliability. The manufacturer of this brand made sure that the products were equipped with the best knives.
When making a choice in favor of this or that knife, you need to remember the specifics of this device, its intended purpose and the main loads that the lawn mower will be subjected to.
- Purpose and requirements
- Varieties and sizes
- Shapes of blades and adapter
- What should be the angle of sharpening?
- How to fix and replace?
- Popular manufacturers
- Selection tips
- Common breakdowns
- Mower does not mow grass
- A rotor with a knife does not spin in the mower
A knife is no less popular than a fishing line or cord, a working tool for a lawn mower. If in the trimmer you can do with fishing line or cord, then the knife is basically a cutter for lawn mowers, whose power is noticeably greater than that of trimmers.
Purpose and requirements
The purpose of the cutter for the mower is to cut the grass evenly and accurately in large quantities. In one session, when mowing one hundred square meters, you can collect tens of kilograms of grass. If the lawn mower has the function of shredding (mulching), such a knife should also grind the grass. The lawnmower cutter is designed so that its blades create upward traction for the freshly cut grass. She carries this grass to the grass catcher.
The best alloy for a mowing knife is stainless steel. Over, it should have a hardness of not less than 55 units on the Rockwell scale. A lower hardness value will quickly blunt the cutter. Especially when cutting weeds and cutting bushes. Since the grass being cut contains not only moisture, but also other active components, ordinary steel would quickly become brown after a first mowing session. Stainless steel, creating chromium oxide on its surface that resists corrosion (chromium is included in the list of alloying additives), does not allow the knife to rust.
Varieties and sizes
Finally, crucial in terms of safety is the material of the torch. Most knives are made of stainless steel, but plastic knives are also found. The fact is that when the cutter bumps into a large stone, the debris of the steel can injure you with a rebound. The impact of a plastic debris is far more harmless. Unless it gets into the eye. Plastic knife. The choice of owners of mowers with a curved flexible shaft. The universal knife for lawn mowers not only cuts grass and shrubs, but also crushes them. Due to the larger number of blades (up to 8). Finely chopped grass will fit as top dressing (mulch) for the lawn.
Shapes of blades and adapter
If it is a simple blade cutter, then there can be several blades. But not more than 8. The shape of the blades of such knives can be as follows:
- Simple (in the form of rectangular ends);
- Rounded (extreme edges have smooth curvature);
- Pointed (in the form of a dihedral wide bayonet).
Bladeless knives. A milling cutter resembling a circular saw on a tree. Such knives are also called circular knives. The number of teeth is up to tens. They remotely resemble a bicycle sprocket, the teeth of which sharpened sharply and changed the direction of the cut. There is a special type of cutter, in which the cutting part is not star-shaped, but stepped. It resembles rounded and curved steps, also spaced evenly. Their steep parts are sharpened sharply. The height of the teeth or “steps” reaches several tens of millimeters.
The adapter is a two-blade adapter for a knife worn on the motor shaft. On the knife side, it has holding rods threaded into the holes of the torch itself. The whole structure is tightened with a central bolt. Simply put, an adapter is a knife holder. On the reverse side, it has serrated grooves matching the teeth of the shaft. It is selected according to the inner diameter of the central hole of the knife (for example, 22 mm).
What should be the angle of sharpening?
Sharpening cutters for a lawn mower is always performed at an angle of 30 degrees. A smaller angle will make the blade too thin, like a razor foil. It will serrate quickly, bend, they can only mow low grass. Weeds and bushes are guaranteed to “hack” the tip. Too a large angle will cause the knife to beat and break the bushes more, to tear the stems of the grass. Than to cut both. In addition, the tip should be sharpened on one side. And only slightly, barely noticeably sharpened on the opposite.
How to fix and replace?
The knife should be changed once a quarter or in the season of grass growth, although sometimes it should be changed earlier. The installation of the knife is as follows:
- If the mower is in operation. Pause it; with an electric braid, just turn off the power (cord from the outlet, disconnect the battery); lawn mowers are switched off with the key, unspent fuel is drained back into the canister;
- Turn the mower on its side and remove the grass catcher;
- Clean the earth and grass adhering to the working parts from the knife and the protective visor;
- Remove the visor (protective cover) of the knife; it delays the grass scattered in all directions (when mowing);
- Unscrew the fastening bolt using a wrench or head, the knife should not turn, it is attached to the adapter; Before removing the knife, it is recommended to wear work gloves so as not to cut yourself;
- Insert a new (preferably exactly the same) knife and tighten the bolt more tightly, when it loosens, the machine vibrates, or the blade itself may fly off.
If there are vibrations, but there is no replaceable knife, it is necessary to balance the old one. Remove the knife and check its balance by hanging it on a screwdriver or nail with a large hat. To do this, the working part of the screwdriver is threaded through the central hole of the torch itself. If there is an imbalance, one specific point will bend, in this case, grind a little metal. With repeated sharpening, the mass of the tip outweighing the others will decrease, and the center of mass will shift to its place. When you are finished balancing, re-attach the adapter and tighten the cutter that is modified in this way. If the adapter has a key that holds it on the shaft of the engine (gearbox), do not forget to press it into place.
Like lawn mowers and accessories for them, for example, knives, produced by popular manufacturers, the best of which are the following:
First of all, the knife must be strong and durable. The best material for knives is stainless steel of the required thickness, and not, for example, black steel with stainless steel spraying or galvanized iron. Sometimes manufacturers indicate a stainless steel brand, for example, AISI 304. A knife is not a part to save on.
For portable lawnmowers, a two-knife blade is considered the minimum solution. In other words, you should pick up a knife with two cutting edges. He will cut grass. But not chop it. To mulch the grass. Buy a cutter with eight points. The optimum sharpening angle is approximately 30 degrees. You will quickly learn to recognize such knives.
The thread of the rotor pins, on which the cutter is mounted with its mounting holes, does not matter. Usually it is left, if the knife rotates to the right. And vice versa. This helps to avoid loosening the nuts and flying off the knife at full speed.
Most often, the malfunctions are as follows: the mower does not mow the grass or does not turn on at all.
Mower does not mow grass
There are two possible options.
- The knife is dull or broken. Sharpen it with a file, an angle grinder, on a grinder (you need a flat-cylindrical whetstone) or on a machine (or drill) with emery wheels. Check torch balancing.
- The cutter itself is not set correctly. Set the clearance in the cylindrical mower between the rotating cylinder and the blades of the knife equal to the thickness of the sheet of paper.
A rotor with a knife does not spin in the mower
There are several options.
- The knife itself is jammed. Pull grass and ground out from under it and scroll the torch itself. It should rotate freely, without scratching or touching the protective cover.
- The drive belt is broken. Check belt integrity. A worn-out, “crumbled” belt must be replaced.
- Break on nutrition. Repair the tattered wire in the cord. Replace cord if insulation is broken.
- The switch does not work. Check the operation of the switch, try turning the mower off and on. If the switch is unusable (melted, burned contacts). Replace it.
- The power supply voltage has disappeared. Check the possible operation of the circuit breaker on the switchboard.
- The plug is not plugged in. Plug in the plug (if it is pulled out).
- The fuse in the device has blown. Check it with a tester (multimeter). Replace the defective fuse if necessary.
- The heat protection of the mower turned off the motor. Wait for the motor to cool after a mowing session.
After checking all the parts and components, finding a malfunction, start the mower. Most likely, your problem will be solved. For fuel lawnmowers, either the carburetor (or drive) or the fuel has run out. Often unstable operation of the motor requires searching and eliminating the breakdown of a number of parts before it is possible to find and replace the faulty one.
How to replace the knife on a lawn mower, see the.