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How to Change & Sharpen Your Craftsman Mower Blades

You may be looking at your yard and noticing that it just doesn’t look as nice as used to look. You begin to wonder how often you really should sharpen your blades. After making a large investment to buy a good Craftsman mower, making sure the blades are not damaged and remain sharp is important to achieve the best cut.

I’ll go through everything you may want to know about your Craftsman mower blades including when to replace and sharpen your mower blades; when you should just buy new blades; how to sharpen the blades yourself and why you may want to have a professional sharpen your blades.

how to change and sharpen your craftsman mower blades

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

This is How Often You Should Change a Craftsman Mower Blade

Craftsman lawn mower blades need to be changed at least once a year and more frequently if your yard includes sand, gravel or rocks. These materials will prematurely wear and damage your blades.

There may be other reasons you may change our mower blades more than once a year including your yard size, how often you mow and whether your blades have been damaged. When changing your blades, you should change them out with a new set of mower blades or blades that have been sharpened if they are still in pretty good condition.

This is When You Sharpen Your Craftsman Mower Blades

While you may not have to change your blades more than once a year, you should sharpen your lawn mower blades after every 25 hours of mowing. This is about twice a year for the average homeowner.

You can often tell you blades are getting dull and not cutting when the tips of the grass turn brown a day or two after you mow it. This is because the dull blades are bruising your grass instead of giving each grass blade a precise cut.

Craftsman Blade Design Can Cause Blades to Wear Sooner

Your mower blade and deck are designed to create a suction in the deck that makes the grass stand tall. In doing so, the mower blades pick up more than just grass. The pick up debris, such as stones and dirt, that cause the Craftsman blade to wear sooner when you operate your mower in dusty conditions with increased levels of dirt and gravel in your lawn.

Items that Can Damage Your Craftsman Mower Blade

Sticks, Rocks and Toys

Toys from pets and kids can damage a blade in addition to rocks and other significant items left in the yard. A bent blade can cause an uneven cut to your yard, damage to a spindle or a vibration in your lawn mower.

Sand & Nature’s Debris

There are some lawns that a very plush with a thick blanket of grass.  If your yard is not one of these, chances are there is dirt and other debris that gets kicked up under your mower deck. This dirt causes premature wearing on your blades.

Lawn Chemicals

Some lawn chemicals that are used today can be very corrosive to your mower and blades. The blades need to be inspected for corrosion and periodically removed so they don’t end up being stuck to your Craftsman mower.

How to Remove You Craftsman Mower Blades

Follow these steps to remove and inspect your mower blades:

  1. Gather tools to remove blades
  • Ratchet Set
  • Work Gloves
  • Safety Glasses
  • Block of Wood
  • Torque Wrench
  • Cordless Impact Gun (Optional)

2. Remove Spark Plug Boot & Ignition Key

It is an important safety precaution to remove the spark plug boot before attempting to remove your mower blades. If your mower has an ignition key, it’s a good idea to remove the key as well. It is important for your safety to complete these steps to ensure your mower doesn’t start when you least expect it.

3. Remove Craftsman Mower Blades

Place a block of wood between the deck and blade so the blade won’t move while you remove the hex flange nut from the center of the blade. If the bolt doesn’t come off easily, you can place a block of wood on the head of the bolt and hit the block with a hammer. Sometimes this works to loosen a stubborn bolt.

4. Reinstall Craftsman Mower Blades

When you are ready to reinstall your mower blades, make sure the sail (which is the higher side of the blade or fin) is pointed upward. Some mower blades are marked “Bottom” to help you determine which side should be on the bottom or facing the ground. Install the blade and secure with the blade bolt. Tighten the blade bolt between 75-90 ft. lbs. using a torque wrench. Do not over tighten as you can damage the spindle.

Inspect Craftsman Mower Blades for Damage

Check your mower blades for the following:

Wearing on the sails: When the sails of the blade are thinner than the center, the blades are worn. This is normal wear and tear. Replace the thinning blades.

Chips and dings: Hitting items in the yard can result in chips and dings in your mower blade. You can typically remove small chips from your blade by sharpening it. If you see large gouges in the blade, you should replace it.

Bend in the blade: Any mower blades that are bent must be replaced. You can identify this by comparing an old blade to a new blade. There is another method to can use when your blade is still installed on your mower.

Park your mower on a level surface and measuring from the ground to one end of the blade. Rotate your blade 180 degrees to measure the other end of the blade. If there is more than an 1/8” difference, your blade is bent and should be replaced.

Do not attempt to try to straighten and reuse your mower blade. This compromises the strength of the metal and could put you in a dangerous situation when it starts rotating at high speeds under your deck.

Cracked blade: Using a blade that is cracked can be extremely dangerous. A cracked lawn mower blade has the potential to break off while mowing which can send flying metal through the air. This could injure a person or cause damage to the siding of a home.

Wearing and damaged blades can cause a bad and uneven cut. Read more about other items that can cause an uneven cut at “Why Your Craftsman Mower Cut is Uneven“.

How to Safely Sharpen Your Craftsman Mower Blades DIY

Sharpening your own blades can save you time and money. There are several different methods you can use to sharpen your blades. You need to remove equal amounts of metal from each cutting edge so it remains balanced. Make sure you wear eye protection and work gloves for safety.

1. Gather the tools you will need

  • 10″ flat metal file, drill powered blade sharpener, or disc grinder
  • A vice to hold the blade in place
  • Blade balancer or nail on the wall
  • Rags
  • Wire Brush 

2. Remove Debris and Dirt from the Blade

Use a rag or wire brush to remove stubborn debris sticking to the blade

3. Use a Vice to Hold the Blade Securely in Place

Sharpen one cutting edge of the blade and then rotate the blade 180 degrees to sharpen the other cutting edge.

4. File or grind blade to sharpen edge.

Sharpen Craftsman blade with a metal file

  • Using a file, push the file at a 25 to 30 degree angle in one direction along the blade.
  • Do not use a sawing motion when filing.
  • Once all of the rough spots and uneven edges are removed, rotate the blade, secure in the vice, and sharpen the other side.

Sharpen Craftsman blade with a drill powered blade sharpener.

  • Power the drill with the blade sharpener attached.
  • Place the flat guide of the sharpener along the flat portion of the blade with the cutting edge slot into the bevel.
  • Move the sharpener up and down the length of the blade edge.
  • Once one side is sharpened without any rough spots or nicks, rotate the blade, secure in the vice, and sharpen using the same procedure.

Sharpen Craftsman blade with an angle grinder or bench grinder

  • Hold angle grinder perpendicular to the edge of the blade. Run the grinder along the length of the blade to level out any rough spots or nicks. Keep the grinder moving so it removes a little metal at a time and produces an even result.
  • Once one side is sharpened without any rough spots or nicks, flop the blade over, secure in the vice, and sharpen using the same procedure.

5. Make sure your Craftsman blade is balanced

Once your blade is sharpened, you will want to make sure it is balanced to reduce vibration and prevent damage to your mower deck. Use a blade balancer that can be purchased at your local hardware store or on Amazon.

If you don’t have a blade balancer available you can place the center hole of the blade over a nail on the wall. If one end of the blade hangs lower than the other end, you will need to sharpen the end that hangs lower until they are equally balanced on the nail. While this isn’t the most accurate way to balance your blade, it’s the best option when you don’t have a balancer.

When You Should Seek a Professional Sharpening Service for Your Craftsman Blades?

Lawn mower repair shops typically offer a mower blade sharpening service. I have my mower blades sharpened by a professional. The reason I choose to not sharpen blades myself is because I can’t put a sharp consistent edge on my mower blade like the tech can.

I’ve had commercial customers bring in dozens of blades to be sharpened. The mower tech can quickly identify bad blades, sharpen the good ones and have them balanced in no time. Because I have my mower blades sharpened at the local dealership, I always keep a spare set on hand so I don’t have to go without my mower. I usually have to leave the blades and pick them up a couple of days later.

You may choose to have a professional sharpen your Craftsman mower blade because of these reasons:

  • It is a safer option than sharpening the blade yourself
  • Sharpening a blade is often less expensive than purchasing a blade
  • A professional can grind down mower blades to get rid of large nicks and gouges in the steel that is hard to remove with your grinding methods
  • The blade is properly balanced. This will reduce vibration, damage to your mower and personal injury.