How to Put a Knife On a Lawnmower Mtd

How to Put a Knife On a Lawnmower Mtd

  1. Required Inventory
  2. Ways
  3. Angle selection
  4. Phased execution
  5. Do I need to sharpen a knife after purchase?

Mowing with mechanical oblique grass in the area can also be done with a blunt knife. But rough cutting of grass with a mower will ruin the appearance of the lawn: it will delaminate in the longitudinal direction. The resulting fringe will be a “callous” look for a few more weeks. To ensure that the lawn is completely and completely flat, it is recommended that you check the lawnmower knife at least once a month and grind it if necessary.

Required Inventory

To align the mower knife, you need the following tools:

  • Angle Grinder;
  • hammer and anvil;
  • coarse sandpaper and a grindstone (in the form of a bar) with a grit of 200-1500 grit;
  • vise;
  • ruler;
  • scrap or wooden stick and a pair of stools;
  • drill with a head for grinding paper or sharpeners (discs).

This list is final. Some tools and accessories may not be needed.

Ways

First of all, it is recommended to remove the knife from the mower.

  1. Manual method of sharpening the blades of a knife. the use of grindstone and sandpaper without any engines and machine tools. Alignment of a serrated and beaten blade with a hammer or sledgehammer is carried out on an anvil, rail or bar of black hire.
  2. Mechanized method, although it is complemented by “blacksmithing” processing, it requires grinding in an angle grinder, saw machine or drill. The last two options will require a special nozzle, on which the grinding disc is put on.

The mower knife is sharpened evenly and along the entire length of (each) point. To prevent the ball bearings of the motor or gearbox from breaking, centering the knife is best done by the lathe on the machine. But even without a lathe, the result will be quite decent.

Angle selection

The angle of sharpening is no less important component than maintaining the balance of the knife in the center. Ideally, it is 30 degrees. Too small an angle will turn the knife into a semblance of a razor blade that is tens of times enlarged and dull at the very first cutting of weeds or cutting of bushes.

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Phased execution

There is no need to look for a master to properly sharpen a knife on a lawn mower. If you know how to handle a manual and mechanical tool, then even without the skills to sharpen knives and blades, but doing everything strictly according to the instructions, Immediately learn how to grind cutters for mowers yourself.

To remove the knife, follow some steps.

  1. Position the mower so that the bolt holding the knife is easily accessible to you.
  2. To prevent the shaft from spinning, place a wooden block under the knife.
  3. Try unscrewing the nut with a 19 mm wrench. Nut size may vary. On many mower models, the knife is secured with a central bolt and is held in place with a lock washer and nut.
  4. If the nut does not turn, so as not to break the edges of the bolt or wrench, soak the threaded connection with oil or grease. Leave it in this condition for several hours.
  5. If there is not enough force on the key lever, strike with a hammer counterclockwise in the direction of turning the nut. In the vast majority of cases, the nut can be removed without problems.

Video: How to Put a Knife On a Lawnmower Mtd


The last two steps will save you an adapter that secures the shaft of the motor or gear to the knife. Without it, the spindle mower will not work. If the torch was not able to be removed with your own hands, then contact the workshop.

Cleaning and editing

After removing the knife, clean it of dried grass residues and dirt. There is no need to clean it to a metallic luster. But on the blades themselves there should be nothing extraneous.

Straightening is carried out using a hammer and an iron bar or piece of rail serving as an anvil. When new breaks and cracks appear when leveling the knife, it is useless to repair such a tip. If, after leveling, the cracks are small, grind off the cracked strip of steel until the blade is completely flat.

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Launching downhills

Descent of the knife blade. the boundary zone between the base of the working part and the edge of the tip. As for kitchen knives that perform completely different functions, descents to the tip have their own normative spread of indicators.

On the knives for the mower, the predominantly “single-slope” descent is used. Too “steep” descent (30-60 degrees). as well as too “gentle” (less than 30 degrees) will lead to a rapid blunting of the tip, a quick loss of its cutting properties. On the cross section of the knife, the start of the cutting edge should not be crooked. Smooth descent, unlike rounded, is much more resistant to pollution and easier to clean.

Blade sharpening

Mower knives are sharpened with:

  • chisels, files and sandwiches;
  • angle grinder (using grinding disks);
  • an electric drill or any motor with a special nozzle on which a round whetstone is mounted;
  • on the emery machine.

Make sure that there are no dents, notches, or potholes on the knife blades. For high-quality sharpening, you most likely will need a vice. they will firmly fix the knife in a position ideal for quick sharpening. Small notches and potholes are removed with a chisel or file or a coarse-grained sharpener.

The sharpening performance will increase when you use a drill with an adapter, on the chuck of which the grindstone or emery wheel is attached. Now plug in and start the drill or sharpener. Start sharpening the serrated edge of the knife.

When sharpening, you should adhere to certain rules.

  1. Do not apply excessive force to the product; gently move the emery wheel.
  2. Avoid overheating from friction when grinding.
  3. Wet the knife periodically with soapy water.
  4. Keep the grinding angle constant. this will help to avoid the effect of the file on the torch. The roughness of the tip, its “pockmarked” fishing line will lead to the formation of the smallest notches in the first minutes of work.
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You can fix the drill or sharpener, and move the knife along the edge of the emery or grinding wheel.

Editing Edges

Experienced craftsmen also perform grinding of a newly sharpened knife.

  1. Instead of a whetstone or emery wheel, place a felt wheel on the motor shaft.
  2. Turn on the engine and apply a little GOI grinding paste onto the circle, gently pressing a piece of the compound against the rotating circle. Get it even on the circle.
  3. Press the cutting torch to the rotating circle and move the sharpened point in any direction. Do not let the tip turn towards the fibers of the circle (do not sharpen “against the coat”). this can spoil the circle itself and cause injury.
  4. If the surface of the circle began to blacken from the metal powder being removed, apply a little more paste on it, and continue processing.

Balancing check

Knife balancing. checking the identity of the mass of the halves of the cutter. Verification is performed as follows:

  1. the knife is put on a screwdriver, pin or nail with a large hat, which will not allow the cutter to fall;
  2. the cutter rises to a small height;
  3. the product is inspected from all sides for an equilibrium bias.

If the knife rests horizontally. the balance is maintained. Rejected. you need to sharpen a little to remove the advantage. Excess layers are removed gradually. The knife is periodically checked for skew. as soon as it lies horizontally, undermining is stopped.

Do I need to sharpen a knife after purchase?

Sharpening at the factory is carried out using a conveyor diamond disk. Nonetheless return the tip to its original sharpness can be no more than 10 minutes. Unscrupulous manufacturers do not always perform high-quality editing after descent and main sharpening.

In this case, the blade, although pressed against the back of the sandpaper, the slope in the direction of the tip is small. The goal is to remove all risks on the descent left after the main stage of sharpening.

In the next video, you will learn universal recommendations for sharpening knives of lawn mowers.