# how sharp are your push mower blades?



## jackallis (Apr 15, 2019)

need to buy new set of mower blades for my Honda HRX - i dont know if need/should sharpen the new blade once i get it to cut my grass on my new lawn.


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## Amoo316 (Jul 8, 2021)

I usually bring my mower blades to the point where they are uncomfortable to touch sharp but not easily cut you sharp.


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## CrispyLawn (Jul 27, 2021)

Amoo316 said:


> I usually bring my mower blades to the point where they are uncomfortable to touch sharp but not easily cut you sharp.


Same here pretty much. Some say you should get them "butter knife" sharp, but I get them as sharp as I can with an angle grinder.


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## jkartchner10 (Jun 7, 2021)

CrispyLawn said:


> Amoo316 said:
> 
> 
> > I usually bring my mower blades to the point where they are uncomfortable to touch sharp but not easily cut you sharp.
> ...


I keep mine pretty sharp too, which usually involves a quick touch up sharpen after about every 2 mows since I have 20k to mow and its pretty rough.

I've found the sharper I keep them the better the grass grows due to the cleaner cuts instead of tearing the grass.


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## SWB (Sep 22, 2018)

I used to keep mine razor sharp until I realized they only stayed that way for about 6 minutes. Someone on here mentioned that some will actually sharpen then run a file across the edge so there's a small flat surface. Supposed to last longer.


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## nameless (Aug 10, 2021)

If you dull them with a file or dull them with grass aren't they both dull and once they become dull from cutting won't they then last as long as the blade you dulled with the file?


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## KJL (Jul 1, 2020)

nameless said:


> If you dull them with a file or dull them with grass aren't they both dull and once they become dull from cutting won't they then last as long as the blade you dulled with the file?


The exception to this is that a hyper-sharp blade edge is theoretically easier to ding (i.e. not on grass), and therefore requires more work to bring to a clean edge again.

I notice the same near-instant dulling but I also recognize torn leaf tips when the blade gets "too" dull.

I probably need to be more scientific about what constitutes "too dull". Currently I sharpen to uncomfortable-to-touch levels as often as I can manage, but I suspect I don't need to be so OCD.


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## Retromower (Jan 28, 2021)

I get mine as sharp as I can. They arent quite straight razor sharp but they are certainly more than butter knife sharp.
I personally use a right angle die grinder. I wouldnt use an angle grinder because its too big, too powerful and its easy to overhead the steel and take the temper out of the blade. A die grinder or rotary tool (Dremel) is a much better option because its less powerful and its much more difficult to overheat the steel. I use sanding pads on my die grinder and I can get the blades stupid sharp without worrying about taking the temper out of them. Before that, I used a Dremel with a sharpening stone. Angle grinders are great but theyre really too powerful for sharping mower blades.


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## MasterMech (Sep 24, 2017)

@SWB I'm usually the one advocating a square cutting edge vs razor sharp for rotary mower blades. :nod:

@nameless A thicker cutting edge may not cut as good as a razor edge for the first 10% of the "time on wing" but for 11%-100% it's as at least as good if not better. Thin cutting edges bend easy and go from being an edge to being a high-velocity bowling pin trying to make tall grass short.

I usually grind at the factory angle, then drag the cutting edge across the belt/stone 1x _-lightly-_ to create a 1/32"-1/16" flat face. (That's .8 - 1.5 mm for those that prefer to think in Base 10. :thumbup: ) The heavier the blade, the closer I get to the fat end of that spec. Of course I'm using a calibrated guesstimater. :bd:


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## PerennialRyeglass (Sep 9, 2021)

I've always used a flap disk on a 5" angle grinder. Gives a beautiful finish and doesn't take material off quite as fast as a grinding stone, provided you're not leaning on it too hard. I keep mine razor sharp. If I run over something unexpected in the lawn and get a ding, I use a 12" long flat file parallel to the length of the blade to re square it and get it even, then sharpen and balance.


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## TheCutShop (Jun 24, 2021)

MasterMech said:


> @SWB I'm usually the one advocating a square cutting edge vs razor sharp for rotary mower blades. :nod:
> 
> @nameless A thicker cutting edge may not cut as good as a razor edge for the first 10% of the "time on wing" but for 11%-100% it's as at least as good if not better. Thin cutting edges bend easy and go from being an edge to being a high-velocity bowling pin trying to make tall grass short.
> 
> I usually grind at the factory angle, then drag the cutting edge across the belt/stone 1x _-lightly-_ to create a 1/32"-1/16" flat face. (That's .8 - 1.5 mm for those that prefer to think in Base 10. :thumbup: ) The heavier the blade, the closer I get to the fat end of that spec. Of course I'm using a calibrated guesstimater. :bd:


How did you test this to come up with your data? Or a link to a study?


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## MasterMech (Sep 24, 2017)

TheCutShop said:


> MasterMech said:
> 
> 
> > @SWB I'm usually the one advocating a square cutting edge vs razor sharp for rotary mower blades. :nod:
> ...


The percentages are pulled from thin air for illustration purposes only. 

I've been grinding blades since I was 14, farms, estates, personal lawns, as a dealer tech, and while working for a golf course. Everybody has a unique need, some of y'all are a little harder on blades than others. If I was a serious YouTuber, I'd put it to the test!


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## Amoo316 (Jul 8, 2021)

If you really wanted to get maximum mileage out of your blades you could always grind the blade to say 30 degrees the add a bevel of like 35 degrees. That would be the "science" way to increase blade life.
If you really want to get into the weeds about blade sharpness and bevel edges feel free to google it. At the end of the day though, if all you're cutting is grass or leaves, and you're not whacking pine cones, rocks...etc, uncomfortable to touch is more than sharp enough.


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## SWB (Sep 22, 2018)

Amoo316 said:


> At the end of the day though, if all you're cutting is grass or leaves, and you're not whacking pine cones, rocks...etc, uncomfortable to touch is more than sharp enough.


+1


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