How Do I Sharpen the Blades on My Riding Lawn Mower?

It’s important to sharpen or replace the lawn mower blade(s) on your riding mower at least once a year, as this provides a deep, even cut over the entire lawn. With riding mowers equipped with twin blades, maintaining blade quality and blade tolerances are important, as the exact tolerances are calculated to provide a premium cut.

Troy-Bilt mower blades are professionally designed by a team of engineers, who precisely select the lift, length and cutting edge of the blades to provide the best performance of the mower. Additionally, blades are tested within a narrow range of specifications to provide a smooth and even cut.

The instructions that follow detail how to sharpen and change the blades on some models of Troy-Bilt riding mowers. For video instructions on how to change the blade on a walk-behind mower, see How to Change Your Walk-Behind Mower Blade. And, see How to Change a Riding Mower Blade for video instructions on changing the blade on your riding mower.

Depending on your model, the following guide on how to sharpen riding mower blades and Troy-Bilt lawn mower blade removal instructions may vary slightly. Always be sure to consult your operator’s manual for detailed instructions.

Sharpen or Replace Riding Mower Blades

Be aware that riders with twin-bladed mower decks may need to have their blades replaced once they have been sharpened past calculated tolerances. On many models of Troy-Bilt riding mowers, the blades need to cross each other while achieving a tip-to-tip contact of within 1/8" of each other when moving.

When lawn mower blades have been sharpened multiple times, so that this gap is larger than 1/8", homeowners may notice a decrease in cut quality, since the blade’s edges may have recessed, allowing for a greater gap between the blades as well as at the outside edge of the deck. When this happens, the blades should be replaced, rather than sharpened further.

How to Remove, Sharpen and Replace Troy-Bilt Riding Mower Blades

To replace and sharpen the blades on a riding mower, follow these steps:

1. Turn the mower off and make sure the engine is cool. Remove the ignition key and disconnect the spark plug ignition wire. Engage the parking brake and chock the back wheels. Be sure the PTO lever is disengaged.
2. Put the deck height lever in its highest position.
3. To access the blades on a riding mower, it’s best to use a mower jack so you can easily elevate the mower, and safely tend to and remove the mower blades. Another option is to remove the cutting deck:
   1. To remove the cutting deck, place a block of wood under the deck’s edge for support, then lower the deck to the wooden block.
   2. Remove the belt keeper from around the engine pulley by removing the self-tapping screw.
   3. Remove the belt from the engine pulley.
   4. Remove the bow-tie clip from the left rear side of the mower deck and carefully remove the hanger rod.
   5. Repeat steps on right side of mower deck.
   6. Remove the bow-tie clip to release the PTO cable from the bracket and release the tension spring from the idler arm.
   7. Remove the wooden block.
   8. Remove the bow-tie clip to release the PTO cable from the bracket and release the tension spring from the idler arm.
   1. Slide the deck out from under the mower.
   10. Turn the deck over to expose the blades.
4. Once the mower has been positioned, or the cutting deck removed and turned over, you can remove the blades, wearing gloves for protection. To do this, you can use the Arnold Blade Removal Tool to secure the blade or use a wood block to prevent the blade from turning. Loosen the blade hardware using a wrench or breaker bar and socket to remove the bolt that secures the blades to the spindle, so you can remove the blades. While removing them, be sure to take note of their orientation so you can properly reattach them. 
5. If sharpening the blades, simply secure each blade in place and run a metal file along each side of the blade’s edge, ensuring you maintain the balance from side to side. You can also use a grinding wheel to sharpen the blade. As an added precaution, make sure to wear a face mask or respirator to avoid inhaling any metal dust from the filing. Do not attempt to sharpen the blade while it is still on the mower.
6. Follow the original angle and grind of the blade when sharpening. Grind each cutting edge equally to keep the blade balanced. To test for balance, remove the blade and balance on a round shaft screwdriver. Remove metal from the heavy side until it balances evenly.
7. Assemble the sharpened or replacement blades on the engine spindle, then tighten the bolts to the proper torque as indicated in your operator’s manual.
8. Remove the Arnold Blade Removal Tool or wood block, if using.
9. Reassemble by following the previous directions in reverse order.
10. Lower and remove the mower jack. Or, if cutting deck was removed, slide the deck back under the mower and reattach components:
    1. Attach the tension spring to the idler arm and insert PTO cable into the bracket. Insert bow-tie clip.
    2. Slide the deck lift rod into the mounting bracket and insert the bow-tie clip into the stabilizer rod.
    3. Attach the hanger rod, then insert bow-tie clips on the left and right side of the mower.
    4. Route the belt onto the engine pulley.
    5. Attach the belt keeper around the engine pulley by inserting the self-tapping screws.
11. Reconnect the spark plug ignition wire.