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#1
Old 05-18-2012, 12:29 PM
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Does a sharp lawn mower blade really matter?

Given that a weed whacker with round-profile string can readily karate-chop its way through grass, I'm wondering about whether keeping a sharp edge on my lawn mower's blade really matters.

People who would like you to pay them for sharpening your blades all insist that it makes a difference, that your grass will be brown-tipped and vulnerable to disease if you cut it with a dull blade. But has anyone here actually observed the difference? Cut the grass one week with a dull blade, take a few pics, sharpen the blade, then cut it again a week later?
#2
Old 05-18-2012, 12:32 PM
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A sharp blade puts less stress on the mower. It also cuts better so grass doesn't just bend under the moving blade. It also helps to prevent clogging.
#3
Old 05-18-2012, 12:37 PM
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Trimmers do 5% of the lawn? Not best cutting method for health of grass, but best for convenience.

Mowers do the other 95%? Yeah, keep that 95% healthy with clean cuts, as you note.

Sharp mowers blades mulch a little better, too. Even better for the soil/lawn.


.
#4
Old 05-18-2012, 12:43 PM
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Anecdotal evidence is all I've got, but I remember one summer of m'youth when my dad was wondering why all our grass blades had split ends. It suddenly dawned on him that he had never sharpened his mower blade. He did so and the problem went away.

Thus endeth the anecdote.
#5
Old 05-18-2012, 12:44 PM
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When I first moved into my house, I had to borrow a mower from some friends. The blade was so dull that the engine would stall on not overly long grass. Sharpened the blade on a belt sander, and it worked great...cut that grass like buttah!
#6
Old 05-18-2012, 01:00 PM
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I'm bad about getting my mower blade sharpened. My friend likes to say, "with that blade, you're not cutting the grass, you're beating it into submission!"

IME, yes, a sharp blade makes for easier mowing.
#7
Old 05-18-2012, 01:12 PM
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Quote:
Originally Posted by Kevbo View Post
When I first moved into my house, I had to borrow a mower from some friends. The blade was so dull that the engine would stall on not overly long grass. Sharpened the blade on a belt sander, and it worked great...cut that grass like buttah!
This is my experience, too.

However, the OP mentions paying people to do the sharpening, and I would never do that. I do it myself a couple of times and then replace it. This is partly because my blade keeps hitting things like rocks that put serious dents in it that you can't just grind out, but also because a new blade for my mower is $20. No point in spending much on sharpening when a brand new blade is so cheap.

(Yes, I would like to avoid the rocks, but making the green belt behind my yard perfectly level and rock/trash free is not a simple weekend project. I'm still pulling tent stakes, blankets, lumber, cement chunks, etc. out of the ground, which is marshy in areas so that new obstacles arise from the depths each year.)

Last edited by dracoi; 05-18-2012 at 01:13 PM.
#8
Old 05-18-2012, 01:16 PM
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weeds tend to be stiffer than grass. you also get good effect by tearing up the weed stem end, you do have edges (on noncircular string) to first cut but then it shreds the remaining end.

a clean cut end on the grass will heal better and loose less water.
#9
Old 05-18-2012, 01:22 PM
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Depends on the grass. My dad had Zoysia grass. Developed by Winthrop Rockefeller in Arkansas, 1960's. Sharpened his blade (himself) on a grinder wheel three times a summer.

Zoysia is a very dense matted grass. You need a razor sharp blade to cut it properly and you need to alternate directions. One time crisscross (the old standby checkerboard). Then the next Cutting diagonal. Then the next circular. Properly maintained it's one of the most beautiful lawns you can have.

Excellent for putting greens too.

You can tell when Zoysia was cut with a dull blade. You'll see this brown powdery stuff in it. One of the few downsides to Zoysia.

Last edited by aceplace57; 05-18-2012 at 01:27 PM.
#10
Old 05-18-2012, 01:43 PM
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Quote:
Originally Posted by dracoi View Post
However, the OP mentions paying people to do the sharpening, and I would never do that.
I only mentioned that because they are the most vocal proponents of blade-sharpening, but they have an obvious self interest in promoting it, so they are unlikely to be the source of the straightest dope.

I guess I'll sharpen my blade this weekend...
#11
Old 05-18-2012, 02:01 PM
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Make sure to disconnect that spark plug before sharpening guys.
#12
Old 05-18-2012, 02:11 PM
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Quote:
Originally Posted by Smeghead View Post
Anecdotal evidence is all I've got, but I remember one summer of m'youth when my dad was wondering why all our grass blades had split ends. It suddenly dawned on him that he had never sharpened his mower blade. He did so and the problem went away.

Thus endeth the anecdote.
I just saw a lawn this week that each blade top was brown for the first 1/4" to 1/2" and shaped like Bart Simpson's head. Pretty nasty looking and it's got to be stressful for the grass.
#13
Old 05-18-2012, 02:16 PM
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Quote:
Originally Posted by tallcoldone View Post
Pretty nasty looking and it's got to be stressful for the grass.
The grass won't care. The special feature of grasses is they grow from the bottom instead of the top.
#14
Old 05-18-2012, 02:17 PM
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Never sharpened mine. What type of business offers this kind of service? And don't say "the lawn mower blade sharpening company." We don't have one of those around these parts.
#15
Old 05-18-2012, 02:18 PM
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Quote:
Originally Posted by Procrustus View Post
Never sharpened mine. What type of business offers this kind of service?
Pretty much any hardware store or small engine shop that services lawn/garden equipment.
#16
Old 05-18-2012, 02:31 PM
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Quote:
Originally Posted by Lukeinva View Post
Make sure to disconnect that spark plug before sharpening guys.
you should disconnect that spark plug before doing anything under the mower deck (including cleaning, pulling or lifting the deck up).

though sharpening can be much easier with the blade off the mower.
#17
Old 05-18-2012, 02:42 PM
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Smaller welding shops often have a grinder wheel. There's an old shop near me where I take my pruning shears, axes, hatchets, and lawn mower blades. They've been in business since the 1940's.

I have three blades that I swap out. When two are dull then I go to the welding, fix it place. That way I always have a fresh, sharp blade ready to use.

Quote:
Originally Posted by Machine Elf View Post
Pretty much any hardware store or small engine shop that services lawn/garden equipment.

Last edited by aceplace57; 05-18-2012 at 02:46 PM.
#18
Old 05-18-2012, 05:00 PM
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I take the blade to my local hardware store. They charge eight bucks.
#19
Old 05-18-2012, 05:19 PM
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I just bought a new blade!

Even though my mower has no spark plug


it's electric!
#20
Old 05-18-2012, 06:11 PM
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I know someone who started their own landscaping company and they do a lot of mowing. By the end of the week, it takes longer to mow, some areas get cut unevenly and he may even need to go over some places twice. Sunday is blade sharpening day for all of his mowers. If he forgets, you can rest assured he won't forget to sharpen them Monday night.
#21
Old 05-18-2012, 06:13 PM
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I have found it makes a bigger difference in a underpowered mower, such as some electrics. If you have enough HP it compensates that you can get a decent cut on a duller blade. Once even put on backwards and it still seemed to work OK.
#22
Old 05-18-2012, 07:47 PM
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People pay others to sharpen thier mower blades!?

I have a DeWalt 4.5 inch soft pad grinder that sharpens the livin' shit outta a mower blade!

Yes, it makes a difference.
#23
Old 05-18-2012, 09:03 PM
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Quote:
Originally Posted by Procrustus View Post
Never sharpened mine. What type of business offers this kind of service? And don't say "the lawn mower blade sharpening company." We don't have one of those around these parts.
My local Sears did. Then they started just replacing blades. Then they only sold the blades for you to replace yourself. Not sure if they do any of that at all anymore. I don't even know if they still have a repair storefront.
#24
Old 05-19-2012, 11:23 AM
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The general rule of thumb is to sharpen the blades three times during the growing season.

If you haven't sharped in a long time (or never), you could mow part of your lawn, sharpen the blades, then mow the rest. I suggest that if you can't tell the difference, you aren't paying attention.

With the string type weed whacker, you really don't have much interest in the health or appearance of the weeds -- the goal is to remove them.
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