how sharp should i get my lawnmower blade??

[WhyMe]

i usually sharpen it with a grinder on both sides till they are like a razor. I have read that its better to sharpen it to a slightly blunt edge as it will last longer and not chip.

so which way is the correct answer

 

[CarbonSteel]

I have done it both ways on a 25HP with a 72" deck and both worked well, but the really sharp one cut the grass whereas the "rolled" edge tended to tear the grass towards the end of the cutting. I noticed the duller blade had the potential for the tips of the grass to brown slightly after a cutting, but the sharp one did not do this.

I think either way works honestly, but it is user preference as to which way to go

 

[Errtt]

I first clean up any muck on the blades.
I usually use a hand file at a fairly aggressive angle. Takes me some time since I have the Honda HRX, 4-cut/quad-cut... whatever they call it. I get it sharp to the touch.
I also have a balancing cone to check each, and then again stacked.
I also clean up the bolt and ensure it has a very light coat of anti-seize. Comes off easy come next time.
I just re-sharpened the blades a couple days ago. It was still in nice shape from last spring. So it was basically touch-up work.
Then run it and pay attention to vibration to ensure I got it balanced close enough for government work.
Cut some lawn and the tips should have a good clean cut.

 

[eljefino]

Two sharp edges with a blunt 1/8"-1/16" standing vertical.

You basically want to mimic a machete.

So you'll have a sharp 90 degree corner and a sharp almost-90 degree corner.

Balance the finished blade on a pencil to make sure you took enough off both sides.

 

[OtisBlkR1]

its funny, i just pulled off my blades and sharpened, im not even close to scientific about this procedure, i take them off, walk em over to my bentch grinder, have at it.. i do a half @SS balance and then throw em back on. I cut 2.5-3 acreas once a week with a 48' deck. Ive learned that in the spring, mid summer.. and depending on the rain maybe again inthe fall they will need resharpened. Ive gotten fairly quick at this too, with the impact and a creeper i can do the whole thing and re-install in about 20 minutes (all three blades)

 

[Pop_Rivit]

I clean them up on the bench grinder, then work the edge a bit with a hand file. They're sharp to the touch, and with some pressure the edge would cut you.

I keep two sets of blades, and swap them every week before I mow. The set that's not on gets sharpened during the week so it's ready for the following weekend. It takes about 10 minutes to swap them out on my 757, and about 5 minutes to sharpen the set that's not on the mower.

 

[fdcg27]

Based upon my experience, it's just a matter of how often you want to sharpen the blades.
It's easy to put a knife edge on the blades with a bench grinder or a Dremmel.
That edge won't last very long, though.
A slightly blunter edge will give more mows.
Just a matter of how often you want to put an edge on the blades.

 

[cat843]

One cannot really do a great job with a bench grindstone. You need a grindstone where you can grind the blade on the flat side of the stone.

While I do not hit too many rocks, I do hit sticks and an occasional marrow (dog) bone.

 

[dkryan]

Cut the grass, don't tear it!

And two thumbs up to Errtt's post above.

 

[rshaw125]

I hit mine with the grinder after changing the oil. Works good.

 

[gman2304]

I use a floppy grinding disc on an angle grinder. Takes only a few swipes.

 

[Nick R]

I use a bench grinder, and get it nice and sharp. Usually lasts pretty well for the full season. Of course I haven't done the lawn tractor yet, still need to do that after I figure out how to raise it to get at the blades.

 

[Hokiefyd]

How long a blade lasts will depend on MANY variables, including grass type, soil type, blade tip speed, blade metallurgy, etc. They usually recommend you leave a very slight blunt edge on it, but I never do. I sharpen my blades yearly, and get them pretty dadgum sharp. We have coarse grass here and very sandy soil, which is heck on a lawn mower blade. I sharpen them yearly and mow.

 

[DBMaster]

I make mine about as sharp as Karl Childers made his in "Sling Blade." My mower is an electric mulcher and I keep my grass cut at the highest setting. The blade stays sharp for the whole mowing season.

 

[dwcopple]

I hit 'em with the 4" angle grinder with a grinding wheel 1-2 times a year.

 

[bvance554]

Tangent.... When and why do you need to buy a new blade? I've been sharpening the same blade atleast once a year for 13 years now. I figure as long as its balanced its good. Is there a point that you should replace it?

 

[Hokiefyd]

Originally Posted By: bvance554
Tangent.... When and why do you need to buy a new blade? I've been sharpening the same blade atleast once a year for 13 years now. I figure as long as its balanced its good. Is there a point that you should replace it?


Over time, the blade will begin to erode away in certain areas. It's not uncommon around here to see blades with holes eroded through the upward "ramp" on the trailing edge of each blade tip. Sandy soil will do that. You live in Virginia; if you have typical firm clay, you can probably make a blade last 10-15 years as you have. Down here, you'd be lucky to get 5 years out of a blade. It depends on a lot of things.

 

[Ausfahrt]

Originally Posted By: Nick R
I use a bench grinder, and get it nice and sharp. Usually lasts pretty well for the full season. Of course I haven't done the lawn tractor yet, still need to do that after I figure out how to raise it to get at the blades.


Just manhandle it up and prop it up on a piece of PVC like I do!

 

[bvance554]

I'll be [censored] if I'm getting under that...

 

[Slacker]

A set of car ramps will get the back end up high enough to get an impact under to take the blades off. Install by hand though! I use a belt sander to get my blades close then finish them off using a file.