Replace your mower blades when you notice your grass blades becoming rough-edged and brown-tipped after mowing. Dull lawn mower blades mean it's time to replace or sharpen them immediately. Our team at Mowrator has outlined a guide on the best time to replace the blade and signs you should look for when identifying when your blades need to sharpen.
Key Takeaways
- You should replace your lawn mower blades every 1 to 2 years.
- Sharpening your blades every 20 to 25 hours of use will increase their lifespan significantly.
- Physical signs like dents, bending, chips, and performance signs should alert you that your mower blades may need replacing.
How Often Should You Replace Lawn Mower Blades?
You should replace your lawn mower blades every 1 to 2 years, although you can afford to stave off purchasing a new blade by sharpening your blades properly. It's worth inspecting the condition of your lawnmower blades every 20 hours of use to see if the blades need to be sharpened. With regular maintenance, you may only need to replace your lawn mower blades after 100 to 200 hours of use, roughly 3 years.
A few lawn mower owners on Reddit recommend you sharpen mower blades 3 to 4 times per season. This will differ if you plan to use your lawn mower for commercial lawn care. Professional usage requires that you replace lawnmower blades at least twice per year.
What Signs Show Your Blades Need Replacement?
The signs that your lawn mower needs to be replaced or sharpened will depend on physical indicators or performance issues while you mow. Knowing when to replace your lawn mower blade instead of sharpening it takes practice, but here are some signs you should look out for:
| Physical Indicators | Performance Issues |
|---|---|
| Visible nicks, dents, or cracks in the blade | Uneven cutting patterns |
| Thinning blade material | Increased vibration during operation |
| Bent blade shape | Extended mowing time requirements |
| Unbalanced rotation | Ragged grass tips after cutting |
| Brown patches appearing after mowing |
What Safety Precautions Should You Take When Replacing Lawn Mower Blades?
Safety precautions when replacing lawn mower blades include ensuring that your lawn mower is turned off and that you are wearing the proper safety equipment to handle sharp blades. This will stop you from getting hurt when touching the blades' edges — which can still harm you even when they are blunt.
| Precaution | Description |
|---|---|
| Pre-Replacement Safety | Put on heavy-duty gloves and safety goggles, securely position the mower on level ground; remove the spark plug, and batteries, and empty the fuel tank |
| Removing the Blades | Tip the lawn mower on its side and place a block between the blade and the mower — secure it with a C-clamp if necessary |
| Installing New Blades | Always double-check the manufacturer's instruction manual to determine the correct orientation and proper fastening methods; don’t over-tighten the bolts |
| Final Checks | Perform a final check of the lawn mower, reconnect the power source, and manually test the blade before starting the engine |
Here's our detailed step-by-step guide for replacing blunt mower blades:
- Pre-Replacement Safety: Put on heavy-duty gloves and safety goggles before beginning, and place your mower on level ground. Position your lawn mower so that no sudden movement will cause the mower to dislodge. Once secured, you can remove the spark plug and batteries and empty the fuel tank — it may be easier to remove these before positioning the mower.
- Remove Old Blades: With the lawn mower on its side, place a block between the blade and the mower deck. You can use a C-clamp to hold the block in place if necessary. Remove the blade slowly and deliberately with a wrench and place it away from you.
- Install New Blades: Always double-check the manufacturer's instruction manual before installing new blades. This will help determine the orientation and how to fasten the new blade properly. Take care not to overtighten the bolt and ensure the fasteners are secure.
- Final Checks: Conduct a final check of the lawn mower after removing the block and C-clamp. Once you're satisfied, reconnect the power source, and when the reassembly is complete, test the blade manually before starting your engine. Listening to unusual noises or vibrations as the lawnmower starts is a good idea, which may validate further inspection.
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When to Replace Mower Blades FAQs
What are the symptoms of a dull lawn mower blade?
You can tell if your lawn mower blade is dull if you see torn, ragged grass and uneven cutting patterns on lanes you've mowed. Unusual fuel usage, lower blade speed, and a louder engine may indicate that your lawn mower works tougher to tear the grass with the dulled set of blades, and the blades need sharpening. If you see physical signs like bending, nicks, or missing pieces, then it’s time to replace your lawn mower blade.
Is it better to sharpen a lawn mower blade or buy a new one?
It's better to sharpen new lawn mower blades if you feel they are beginning to dull, preferably every 20 to 25 hours of use. You should only replace old blades or new blades with physical dents, bends, or chips that could prove dangerous and detrimental to your lawn care.
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