Unless your yard is pristine golf course like grass i would not worry about sharpness of blades. You run over sticks, stones, sand, dirt, mulch and other things that will dull your blade quickly. Keep it straight edge, but not razor sharp.
New lawn mower blades don't seem very sharp
- Thread starter Donald
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Don't comment here to much, but hadda jump in on this, as I owned a lawn mower sales and repair shop for 50 years, and sharpened thousands of blades. I totally agree that blades don't need to be razor sharp to cut fine, and will dull faster if they are, BUT the customers really like them to look like that. Weird thing is even though I sharpened them very sharp, Many of my repeat customers, ( which was most of them), told me that my sharpening jobs stayed sharp longest
Yep, I've sharpened thousands of mower blades. My go-to is still the flap sanding disk on an angle grinder.
I’ve read/heard that blades should be blunt not sharp.
Here are my thoughts;
1)
Is there engineering data to support this opinion?
2)
If we sharpen a blade to a sharp edge like a knife it will blunt (round over) rather quickly and resemble the blunt edge which the (experts) prefer.
During this blunting process the sharp blade is cutting grass like a new razor cuts your whiskers! So wouldn’t a blade with a knife edge cut more grass before it requires attention?
It starts sharp then (blunts) similar to a new factory blade, wear stabilizes until it rounds over.
3)
How are you going to duplicate the factory edge on a used blade?
Blades don’t wear evenly they taper out to end so the only thing you can do is grind it to a sharp edge and call it a day.
4)
I use my blades until the lift and ends erode while always checking for fatigue cracks.
I sharpen them when they no longer cut cleanly and bog the engine down.
I also balance blades every time I sharpen them.
5)
I agree with a previous poster that said perhaps a sharp blade is a liability!
90cummins
Here are my thoughts;
1)
Is there engineering data to support this opinion?
2)
If we sharpen a blade to a sharp edge like a knife it will blunt (round over) rather quickly and resemble the blunt edge which the (experts) prefer.
During this blunting process the sharp blade is cutting grass like a new razor cuts your whiskers! So wouldn’t a blade with a knife edge cut more grass before it requires attention?
It starts sharp then (blunts) similar to a new factory blade, wear stabilizes until it rounds over.
3)
How are you going to duplicate the factory edge on a used blade?
Blades don’t wear evenly they taper out to end so the only thing you can do is grind it to a sharp edge and call it a day.
4)
I use my blades until the lift and ends erode while always checking for fatigue cracks.
I sharpen them when they no longer cut cleanly and bog the engine down.
I also balance blades every time I sharpen them.
5)
I agree with a previous poster that said perhaps a sharp blade is a liability!
90cummins
i got some Predator brand blades through John Deere (has a JD part number) that are gator like. Didn't bother sharpening them as they had a fairly heavy coat of paint on them. Figured it would wear off. It didn't. But had to stop and balance them after about 15 minutes. The mower was shaking itself to pieces. Still not as good as the OE blades I took off.
I just put a pair of the Gators on my 42" Craftsman rider...didn't sharpen them..yard looks like Augusta National.
Something often overlooked is the sharpening angle.
I've seen the edge sharpening debate on professional lawn care forums.
Right or wrong, after I machine sharpen a blade, I use a hand file to put a micro bevel on the edge. Still very sharp, but slightly less prone to folding over/dulling immediately. Otherwise, I have other obsessions that deserve more time than this one.
Butter knife sharp rather than razor sharp.
Now which knife is the butter knife?
Now which knife is the butter knife?
I took those Predator blades off again as there was still a balance problem. Part is the thick paint and stickers . Most of the paint had worn away except in the center of the blade. I wire wheeled it all off. They were still sharp enough I had to use a glove for protection to take them off.
The Oregon Magnum Gatorline .105” isn’t sharp and can cut down small trees and big weeds.
I wonder what the rpm is on a Husqvarna FR 336 weed whacker?
Yep! The original, untouched blades on my Ariens Apex are still cutting well and nice & even with 170 hours on them. A tip speed of 18,000 fpm (205mph!) means the tempering of the steel & durability of the edge is much more important than a “finger-sharp” cutting edge.
Ariens actually shows in the manual that if you sharpen them, the proper grinding is only on the top side of the blade and will actually make the width of the tip thinner over multiple grindings.
The one you substitute as a slotted screwdriver in a pinch, or as a prybar for paint can lids
Started sharpening blades as a hobby, now it's my impromtu side hustle that has spread way past my immediate neighborhood. Even have business cards with it's name; Mow'r Sharp 
. Currently use an All American Sharpener jig with my cordless Makita angle grinder and 60 grit flap wheels for about 90% of the blades I profile. I have found angle is very important and should be maintained as close to factory as possible for best cutting. Ruined a bunch of Honda Micro Cut mulching sets because I sharpened at a 30° angle instead of the factory 40° one. Once I figured that out, they cut better and last way longer. I now maintain a list of cutting angles for most of the blades I encounter. Started doing a final angle dressing like @doitmyself describes and works very well for initial cutting and "folding" to it's working edge. Lasts a long time this way.
Oh, and if the IRS is reading here, I do NOT deal in cash or any other form of monetary payments. Old fashioned bartering keeps me deep in beer, cigars and bourbon.
. Currently use an All American Sharpener jig with my cordless Makita angle grinder and 60 grit flap wheels for about 90% of the blades I profile. I have found angle is very important and should be maintained as close to factory as possible for best cutting. Ruined a bunch of Honda Micro Cut mulching sets because I sharpened at a 30° angle instead of the factory 40° one. Once I figured that out, they cut better and last way longer. I now maintain a list of cutting angles for most of the blades I encounter. Started doing a final angle dressing like @doitmyself describes and works very well for initial cutting and "folding" to it's working edge. Lasts a long time this way.Oh, and if the IRS is reading here, I do NOT deal in cash or any other form of monetary payments. Old fashioned bartering keeps me deep in beer, cigars and bourbon.
Yes. The pitch of the angle is key. A keen edge will roll up and is worthless.
I sharpened a blade for a useless 40v kobalt mower for a customer, ground it about 30 degrees and made the edge knife like. She says the mower works better now than when it was new.
I charged a 12 pack.
I charged a 12 pack.
Years ago, I talked with a Rep from John Deere.
The way he explained it, if you sharpen your blades razor sharp, the cutting edge will be very thin and fragile and will dull and chip easily.
If you sharpen at a less aggressive angle, the cutting edge is thicker and will hold it's edge a long time.
The way he explained it, if you sharpen your blades razor sharp, the cutting edge will be very thin and fragile and will dull and chip easily.
If you sharpen at a less aggressive angle, the cutting edge is thicker and will hold it's edge a long time.
While my lawn is certainly no golf course, it is quite nice and I use sharp, sharp blades to keep the tops of the cut grass from noticeably browning. I can really tell the difference when it starts to dull and it drives me nuts. Everyone’s mileage will vary.
