How to Sharpen Reel Lawn Mower Blades at Home
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How to sharpen reel lawn mower blades at home: you backlap them: apply a fine compound to the reel and turn it backward so the blades grind against the bed knife. Start with the mower disabled and the blades secured, and check that the reel just touches the bed knife. Reel mower guides say the method is the easiest approach for most owners, and that bench and hand grinders are the wrong tools. The steps here follow that method, and they point out where a reel mower differs from a rotary mower.
Quick answer
- Backlap with a reel sharpening kit or a fine valve-grinding compound, turning the reel backward.
- Disable the mower and block or pin the blades before you start.
- Set the bed knife so it is parallel to the reel and just touches it.
- Skip bench grinders and hand grinders, which are the wrong approach.
Know what a reel mower needs
A reel mower cuts by scissor action. The spinning reel passes a fixed bed knife, and the two edges shear the grass. Both edges must be sharp, and they must sit close together. When the blades dull, the grass tips tear instead of cutting, and the mower feels heavier to push. Reel blades rarely need sharpening, so check the cut before you start work.
Some reel mowers are sold as manual cylinder mowers, and the same method applies. The Gardena Classic 16-inch reel mower, for example, uses a hardened, non-stick coated cutting cylinder that turns past a fixed counter-blade. The listing for the Zoryx 14-inch five-blade reel mower describes alloy steel blades that stay sharp longer. Both listings describe the blade design but do not give sharpening steps, so the steps below come from the reel mower guide.
Signs the blades need sharpening
- The grass tips look brown or ragged after a cut.
- The mower is harder to push and gives more vibration.
- The cut is uneven across the lawn even after you check the height.
- You find nicks on the blades from rocks, curbs or pebbles.
Pebbles, curbs and rocks are common causes of dulling. If you mow a lawn with many stones, check the blades more often.
What you need
- A reel blade sharpening kit with a handle that fits the drive gear, or a fine valve-grinding compound.
- A brush to spread the compound.
- A file for large nicks.
- Eye protection and gloves.
- Optional: a drill with a rotary sharpener attachment.
- A light coat of low-acidity vegetable oil for afterward.
Step by step
Step 1: Disable the mower
Turn off the mower and keep your fingers clear of the reel. If the blade is not detachable, pin it so it cannot rotate. If the mower has no arresting gears, place wooden chock blocks between the blades. A sharpener with finger guards keeps your knuckles away from the cylinder.
Step 2: Set the bed knife
Tighten the bed knife until the reel blades just touch it. Make sure the bed knife runs parallel to the reel. If it does not, some blades will sharpen more than others, and the cutting height will vary across the lawn.
Step 3: File nicks smooth
Use a file to smooth any large nick before you apply compound. The compound cannot remove a deep nick on its own. Work lightly and stop once the nick is flat.
Step 4: Apply compound
Brush a thin layer of compound across all the blades. Cover the full length of each blade, but do not overload it.
Step 5: Backlap
Turn the reel backward by hand or with a drill and the right attachment. The blades grind against the bed knife and form a smooth edge. Reverse rotation reduces blade wear. Keep going until the edge looks even across the reel, then wipe the compound off and check the blades.
Step 6: Clean, oil and test
Clean the blades and bed knife, then apply a light coat of low-acidity vegetable oil to prevent rust. Adjust the height, mow a short patch of dry grass, and look at the tips. A clean cut shows a smooth edge.
When backlapping is not enough
If the blades are badly dull or heavily nicked, backlapping may not restore a sharp edge. In that case, the blades may need replacing. Sharpening also cannot fix a mower whose bed knife is loose or out of parallel. Fix the adjustment first.
Mistakes to avoid
- Using a bench grinder or hand grinder, which are the wrong tools for a reel blade.
- Working on the reel while it can turn. Lock or pin it first.
- Skipping the bed knife check, which leaves an uneven cut.
- Leaving the blades bare after sharpening. Oil them lightly.
FAQ
Do I have to take the reel out to sharpen it?
Not always. One reel mower guide says you sharpen the blades while they are still attached. Other sources recommend detaching them where the design allows. Check your manual.
What is the difference between a reel mower and a rotary mower for sharpening?
A reel mower cuts by scissor action, so the edge of each blade and the bed knife matter. A rotary mower uses a spinning blade that strikes the grass. Reel sharpening uses the backlapping method described here.
Is pushing the mower forward enough to keep blades sharp?
Some sources say forward motion helps the blades stay sharp. That effect is weak and unreliable, so deliberate backlapping is the better method.
How often should I sharpen the blades?
One guide suggests at least once a season for a mower used often. Sharpen sooner if the cut looks torn.
Can I use a power drill?
Yes. A drill with a rotary sharpener makes the job faster. Use it at a slow speed and keep the compound on the blades.
What oil should I use?
Use a light coat of low-acidity vegetable oil, then wipe off the excess.
Bottom line
Sharpen reel lawn mower blades by backlapping with a fine compound after you disable the mower, lock the reel, and set the bed knife parallel and just touching. Skip grinders. If the cut does not improve, the blades may be too damaged to fix at home.
Related guides
For a wider look at blade care, read How to Sharpen a Mower Blade Safely. For reel and robot mower choices, see Best Replacement Mower Blades, and the Reel and Robot Mowers Listed Beside Them.
