Do you bother to sharpen your lawn mower blade? Why?

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Does anyone bother sharpening their lawnmower blade?
According to the searspartsdirect web site, it costs about $15 for a new lawn mower blade for my Craftsman 917.388853 6.5HP 21" push lawn mower (Briggs & Stratton engine 123K02-0444-E1), plus 10% sales tax & 10 dollars shipping. I'm sure it will cost double or triple that to have someone else sharpen it, assuming standard labor rates of $100 to $200 an hour out here.
The owners manual (on page 12) recommends against sharpening the blade. http://www.managemylife.com/mmh/lis_pdf/OWNM/L0505023.pdf
The blade seems to cut well no matter how many rocks I hit (I have other problems like a sheared flywheel key, but the grass was getting cut even with a five-year-old dinged up blade).
My question is: Does anyone bother sharpening a blade?
The reason I ask is it will likely cost more to have someone sharpen the blade than the blade costs and my blade seems to cut as well now as when new five years ago, even after countless rocks and tree stumps have been "mulched" by the blade. Those things are practically indestructible.
Do you bother to sharpen your blade? Why?
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James H. wrote:

Hmmm, I sharpen it myself when blade becaomes dull. You can tell the difference between good blade and dull blade. Dull blade does a poor job of cutting. It just beat up the grass blades. Compare between two grass tops. One cut with a good mower blade and one with dull blade.
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========================================================
Couple of years ago used to cost $3 to $4 around here. Biggest job is often getting the blade off!
Easy enough to do on a bench grinder or in a vise with a big 'bastard'' file.
But make sure the blade is balanced afterwards.
Recently modifying and rebuilding a mower was able to shorten a blade by grinding off the ends and then sharpen it.
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On Mon, 5 Jul 2010 23:53:26 -0700 (PDT), terry wrote:

This video is from a very experienced lawnmower mechanic who advises against removing the blade to sharpen it.
http://www.youtube.com/watch?v=HDQ0elcCOlY&feature=channel

The owners manual recommends removing the blade if it's gonna be sharpened. Why?
Why do all the manuals recommend removing the blade to sharpen it while this admittedly very experienced mechanic says not to bother?
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On Tue, 6 Jul 2010 00:07:50 -0700, "James H."

I can't watch the video now but I presume he counts the number of strokes he uses and has enogh practice to make sure the strokes are with the same amount of pressure and the same distance from the center on each end. That is 2 strokkes at 8 inhces, 2 strokes at 7.5 inches, 2 a5 7, etc. on both ends of the blade. If one did that well enough, evenly enough, the blade would still be balanced when one was done.

AFAIK, so it can be balanced afterwards.

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On Tue, 06 Jul 2010 03:26:34 -0400, mm wrote:

He doesn't use a file. He uses a hand-operated grinding wheel (DeWalt type). It is interesting to note how he does it w/o removing the blade.
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Nope-- I watched it. he gets to sharpening at about the 4 minute mark. He uses an angle grinder.
For a $50 mower I might do the same. Otherwise I either take it off so I can balance it, [I look at that struggle as a practice run for blade replacement] or I do the above with a file.
Or more likely I just wait until I think it needs it and replace the blade-- leaving the old one on the bench to be sharpened at some future date-- hoping the mower has died by then and the new one takes a different blade.

It is also a bit safer. The mechanic never mentioned that you should always remove the sparkplug when messing with the blade. Compression can bump a blade enough to do damage.

Sometimes experience doesn't equal wisdom. . . nor does it necessarily mean you are a good teacher.
Jim
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On Tue, 06 Jul 2010 07:08:30 -0400, Jim Elbrecht wrote:

Hi Jim, Thanks for watching the video. I should have mentioned it was about 4 minutes in that he sharpened the blade. I appreciate your time and effort.
I wouldn't remove the sparkplug; but I would pull the wire off the spark plug (and yes, the mechanic didn't mention that).
He ground the upper part of the blade and then the lower part briefly with the angle grinder but I agree he didn't balance it afterward.
The owners manual I have says to hammer a nail protruding out of a wall stud and hang the blade horizontally on that nail from the center hole to balance.
So, even if I sharpened the blade on the mower, I'd still have to remove it to check the balance. I guess he has so much experience that all his checks showed his blades were still balanced after he sharpened them.
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Can't balance blade while on mower. I sense the old guy is tired, and doesn't want to be bothered.
--
Christopher A. Young
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On Jul 6, 7:51am, "Stormin Mormon"

I sharpen mine occasionally with a hand grinder. I never bother with the balancing.
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On Tue, 6 Jul 2010 05:09:30 -0700 (PDT), jamesgangnc wrote:

I've never sharpened a blade before.
May I ask:
If I sharpened the blade, and if it was slightly unbalanced, would I know it was unbalanced when I started up the lawn mower?
If yes, then there's less reason to balance ahead of time; if not, then why bother balancing?
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On Tue, 06 Jul 2010 06:09:00 -0700, James H. wrote:

Not likely you would notice unless it was grossly imbalanced. Most of the time you are just going to cause the bottom crank bearing to wear a bit quicker if the imbalance is slight. I pull the deck off my Deere LT155 twice a year and lube the shaft bearings, power wash the underneath, and grind the blades on a jig I made my self. I have a little cone shaped thing to check the balance which is usually close enough for me. This is a 10 year old tractor with only the deck belt needing replaced so far.
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I've watched people balance them but I just don't see any reason to. I think they would have to be grossly out of balance to matter. I don't try to grind out any really huge nicks. If 90% of the blade has a sharp edge I quit. After about a 1/4 of the blade is gone I buy another one. My old lawnboy got retired to our lake house about 8 years ago where it's now 18 years old. Never balanced a blade on it in that whole time. I'va had to put a few parts on it but never any motor internals. May matter more if you are a pro running your equipment 6 - 8 hours a day.
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A little vibbbrrratttiiioonnn nevvvveer hurt annnyonnneee????
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James H. wrote the following:

He doesn't advise against removing the blade. He says 'HE" doesn't remove it.

Again, he is showing an alternative to sharpening without removing the blade. He doesn't say NOT to remove it. Do you have one of those grinders?
--

Bill
In Hamptonburgh, NY
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On Tue, 06 Jul 2010 16:37:04 -0400, willshak wrote:

Good point.

Yes. I have a Dewalt grinder just like that, only my stone is new (his was old and maybe old is better).
I also have dremel tools and files but for now, I think we have our answer on the sharpening:
a) Some people never sharpen; others do about yearly. b) It won't make much different; but it might make some difference. c) Almost everyone removes the blade to sharpen & balance; some don't. d) Easiest balancing method I've seen is that which the Craftsman manuals says to do which is to hang the blad on a nail horizontally. e) A new blade (for my mower) is $14.50 + 10% tax + shipping to CA; while the nearest Briggs & Stratton shop won't charge less than $45 to sharpen (I didn't ask about tax) and I have to bring the lawnmower and/or blade to them.
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James H. wrote the following:

I remove the one nut holding the blade, which takes about 5 minutes, and sharpen it with a bench grinder. I have more control on how much to remove and I am able to balance it. My 18 x 46 tractor's mower deck has three blades. I remove the whole deck before winter because I have a snow blower attachment that goes on the tractor. I have all winter to remove and sharpen the three blades. You might be able to get a replacement blade at HD or Lowes. Check their one-line mower supplies.
--

Bill
In Hamptonburgh, NY
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On Tue, 06 Jul 2010 14:01:49 -0700, James H. wrote:

I try to do it yearly, but if I forget I don't lose any sleep over it...

I just replaced the blades on the lawn tractor - huge difference in cut quality between new and old; I think the old ones often beat the grass more than cut it, and it'd lay flat for a day or two and then spring back up and look nasty.

Yeah, I've never done that on the lawn tractor - takes me about ten mins to pull the whole deck, and I can get in there with a grinder to sharpen the blades in-place (I've been known to sit the whole tractor up on its butt instead, but my back hates me for it). I realise we're talking about smaller mowers here though, but if there's space to get a grinder in I can't see a reason to take the blade off.

I paid $6 per blade at a local farm supply place; cheapest I'd seen online were $15 (without shipping cost) for the same thing. Having said that I really should have bought mulching blades, and I think those were $9 each.
cheers
Jules
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On Wed, 7 Jul 2010 14:15:46 +0000 (UTC), Jules Richardson wrote:

The prices you quote seem like Kansas prices ... not California prices (which are triple anything quoted so far) ...
But, may I ask ... What is the difference between a MULCHING blade and a regular blade?
Are they interchangeable?
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Mulching blades usually have a higher lift / blade tilt to them
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