Sharpening a mower blade is a routine mower maintenance procedure which will allow your mower to continue cutting at peak efficiently. To assure best results, most residential mowers should have the blades serviced annually.
CAUTION! Blades are sharp. Persons performing this service should always wear heavy leather gloves. Before performing blade maintenance on any unit, always disconnect and ground the spark plug wire.
IMPORTANT! These instructions are prepared for use by trained technicians who are experienced in the service and repair of outdoor power equipment, and are not intended for use by untrained or inexperienced individuals. Such individuals should seek the assistance of an authorized service center. If further assistance is needed, please utilize the Authorized Service Center Directory to search for a local authorized service provider.
- BLADE REMOVAL:
- To sharpen and balance a blade, it must first be removed from the mower. Walk behind mower blades are installed between 38 and 50 foot pounds of torque, and riding mowers are between 70 and 90 foot pounds of torque using a standard bolt thread pattern, which is also referred to as right-handed or clockwise thread. Corrosion and dirt may also result in blade retaining hardware to become very tight. The use of a long-handled wrench will increase leverage and reduce the amount of force needed to remove tight hardware.
- Standard thread parts loosen by rotating them counterclockwise.
- Riding mowers may need the deck to be removed from the unit in order to properly gain service access to the blades and spindles. Automotive service style front-wheel ramps and tire chocks, placed in front and behind each tire, should be properly used to safely gain access and prevent movement of a riding mower, if the deck is to remain on while performing this service.
- DO NOT TURN THE ENTIRE MOWER UPSIDE-DOWN. Inverting the engine improperly will likely result in engine damage from fluids flowing into internal engine compartments where these fluids are not welcome.
- Walk-behind mowers (not riders) may be tilted onto the side opposite of the mower engine's carburetor and air filter. Always keeping the engine carburetor and air cleaner up will help prevent crankcase oil from flowing into these areas. A plastic bag placed over the fuel tank fill port and secured with the fuel cap will help to prevent fuel leakage from the fuel cap area.
- SERVICE TIP! When removing and installing blades from the mower, the blade and shaft may spin as the retaining nut/bolt is rotated. To prevent this, place a block of wood inside the deck to serve as a blade chock to stop the blade from rotating as the retaining nut or bolt is turned.
- BLADE SHARPENING:
- Once the blade is removed, use a proper metal sharpening tool, such a hand file designed for use on hardened metal, on the leading edges of the blade. It is not necessary to sharpen the blade so that it is as sharp as a knife blade, a simple clean edge, with the metal sharpened at about a 45 degree angle is sufficient. The tips of blades do most of the cutting, most blade wear will be visible in this blade tip area which will need the most attention during sharpening. If the blade is significantly worn OR has large dents in the cutting edge from impacting hard objects, the blade should be replaced with a new one.
Visit our Online Parts Store to purchase replacement blades and service parts.
- BLADE BALANCING:
- Before re-installing a sharpened blade, it is necessary to check for balance. A blade out of balance can cause vibrations that may weaken or loosen components on a mower. Mower blade balancing tools are generally inexpensive and available from most hardware stores.
- Note: If a blade balancing tool is unavailable, an alternative method is to use a nail hammered into a vertical plank or wall stud in. The nail and blade will then make a hanging cross-configuration when the blade is placed onto it.
- If the free-hanging blade begins to rotate or one side of the blade is then pulled toward the ground, then the side that rotates toward the ground is heavier. The heavy side would require some additional sharpening in order to remove some material and properly achieve balance. Continue to test for balance until the blade no longer rotates and balance between the two sides is achieved.
- BLADE INSTALLATION:
- After the blade is properly sharpened and balanced, re-install it making sure that the blade is oriented in the proper fashion.
- OEM blades are stamped with the part number and the word "Bottom" on the side that should face the ground. Most likely the blade also has a air fin or bend on each trailing edge. This air fin should point up towards the bottom of the mower deck and not down towards the ground.
- To tighten the bolt or nut use a torque wrench and tighten it to proper torque specification.
-
- Walk behind mower blades should be installed between 38 and 50 foot pounds of torque.
- Riding mower blades should be installed between 70 and 90 foot pounds of torque.
