# Lawnmower Blade Sharpening



## Mozart (Jul 17, 2018)

I'm not sure if I need to sharpen my blades. Didn't feel any big nicks but I did accidentally hit a root last mow.

It's not sharp like a knife, just has a defined edge. Should it be as sharp as a knife?

Would you sharpen the blade? See pics below (both sides of blade shown):


----------



## Suburban Jungle Life (Mar 1, 2018)

I prefer mine sharp like a knife. Cleaner cut.


----------



## Harts (May 14, 2018)

I run the nail on my thumb downwards against the blade several times in several places. If it's sharp it will create nail shavings.

Old hockey skate trick to check the sharpness!

If you are unsure, get it sharpened. The guy I go to shakes his head every time I walk in because he knows my blade doesn't need to be sharpened! But I do it anyways. He charges me $15 and it takes him 3 minutes.


----------



## social port (Jun 19, 2017)

I also use the nail test. 
It is surprising how often my blades need some work.


----------



## NJ-lawn (Jun 25, 2018)

Do new lawnmower blades need sharpening? I know they don't come that sharp.


----------



## Alex1389 (May 23, 2018)

I sharpen every 6-8 mows (once a month). Local place charges me $7/blade. I keep a spare set around as well.

If you've never sharpened that blade, I'd go for it. I know those Ego mowers really need to have a sharp blade for best performance as well.


----------



## Suburban Jungle Life (Mar 1, 2018)

NJ-lawn said:


> Do new lawnmower blades need sharpening? I know they don't come that sharp.


They might be sharp under all that paint but better to be sure and sharpen it. At a minimum, I would use a file and remove the paint to see what kind of edge it has.


----------



## ForsheeMS (May 21, 2018)

I sharpen mine often. After mowing I stick my hand under the deck (engine off of course) and feel one of the blades. If they don't have a good sharp edge they will be sharpened before the next mow. I do my own and use a flap wheel on a right angle grinder. Takes me far longer to remove and reinstall all 3 blades than it does to sharpen them.

AS far as new blades, I've never seen a set out of the box that was sharp enough. I always sharpen them and then check the balance before installing. Yes, I've seen a few brand new blades out of balance from the factory but doesn't happen very often.


----------



## Rucraz2 (Apr 8, 2018)

^ agree. Out of the box they are never sharp enough. I have used quite a few methods thinking I was getting a good sharp edge. My cut was never up to satisfaction though. Until I used the flap disk and angle grinder. Whole new ball game after that.


----------



## SNOWBOB11 (Aug 31, 2017)

Suburban Jungle Life said:


> I prefer mine sharp like a knife. Cleaner cut.


I definitely agree with this. Some people say it's not a good idea to sharpen a lawnmower blade like a knife but I always find it gives the best cut by far.

Also if anyone is thinking about trying to sharpen there mower blade them self instead of paying for it then go for it. It's easy and you can do it just as good. As long as you keep the blade profile It will work out fine. I use a bench grinder but you can use a angle grinder (I've never done that one) or a simple file to keep it sharp. Beats paying for something you can do in 10 minutes yourself.


----------



## ctrav (Aug 18, 2018)

Northern Tool in my neck of the woods had a sale on an angle grinder so I picked one up just so I can learn to sharpen my own blades. It will be fun :thumbup:


----------



## Rucraz2 (Apr 8, 2018)

Use the flap disk. Its much more forgiving and keeps a more accurate angle.


----------



## ctrav (Aug 18, 2018)

Rucraz2 said:


> Use the flap disk. Its much more forgiving and keeps a more accurate angle.


I just looked up flap disk and Amazon has a set of 20 for $22. Im sure that 20 pack will last a lifetime


----------



## Rucraz2 (Apr 8, 2018)

Yeah. I would hope so. I think I got mine at harbour freight for next to nothing.


----------



## JohnP (Oct 24, 2017)

I've got an angle grinder, I threw a flap disc on and sharpened my blades myself for the first time last weekend. Prior to that I was taking them to a shop near work that did it for $5/blade. Similar rotation as those above, I'd switch out once a month usually. I have three blades, the one that came with and two mulching blades. I mostly use the mulchers, but the other I used when scalping. Let it get beat up instead of my mulching ones.

Whether you do yourself or take to a shop doesn't matter, just make sure they're sharp.

Also, new blade does not mean sharp blade.


----------



## TrialAndError (Oct 7, 2017)

I bought the All American Sharpener jig, and Love it. Makes sharpening blades extremely easy.. https://www.allamericansharpener.com/


----------



## FuzzeWuzze (Aug 25, 2017)

As i understood it, making razer sharp blades was a no no because your more likely to round over the edge on the bottom side which means your blades will dull faster.


----------



## Bman1 (Dec 8, 2018)

Lawnmower blades aren't knife sharp, basically a clean edge at the proper angle. The sharper you make it, the thinner you make it, so it will dull easier. Just keep the angle. 
I use an angle grinder with a flap disc. Love the all American jig, but haven't sprung on one yet!


----------



## Global Threat (May 16, 2019)

I second on the flap disc and angle grinder. You can buy different grits for it as well. I finish off with a 320grit and I could shave with the mower blades.


----------



## jingobah (May 6, 2019)

I bought a replacement blade from the local HD & it was as sharp as a bowling ball. I used a file which I thought gave me more control. Second time sharpening it I used a grinder wheel & didn't really care for that method too much. I'll try the flap disc next on my angle grinder.


----------



## ctrav (Aug 18, 2018)

I use a flap disc and angle grinder as well. Not going for a super sharp edge just clean it up and try to keep the angle. seems to work well. I have two sets of blades and change every month but may start changing every two weeks due to increased cutting (if its not raining). I read or heard that blades that are razor sharp dull much quicker. In which case that may mean changing every week...


----------



## Boberto (Apr 28, 2019)

I'm interested in trying the flap disc method, the most cost effective route is going through amazon, but you end up with 10+ discs. :? Looks like HarborFreight/Menards would be the next best at $4/per.

Any particular grid recommendations?


----------



## Dkrem (Mar 16, 2019)

I use my 4x36 bench belt sander with 80 grit Zirconia belt. Takes off metal like a hot damn and leaves a nice edge, no roundover.


----------



## MMoore (Aug 8, 2018)

Dkrem said:


> I use my 4x36 bench belt sander with 80 grit Zirconia belt. Takes off metal like a hot damn and leaves a nice edge, no roundover.


how are you doing the profile of the blade?

my 6x89 with 36 grit ceramic belt is too big to get into the blade itself. I just use my grinder with an 80grit flap and then knock off the hard grinding marks with a surface conditioning wheel.


----------



## Dkrem (Mar 16, 2019)

MMoore said:


> how are you doing the profile of the blade?


Not sure if you are asking for geometry or process.

geometry:
I maintain the factory chisel grind.

process:
I have flat/conventional gator blades. With the sander off I do a dry run and lay the edge on the belt and rock and move it to find the best approach (usually about 45 deg to the platen, as close to full width as possible) and get my brain and muscles around where the bevel angle is. Then I turn on the belt and just lay into it. I always grind off the edge and once I find the bevel I work until I see the carbide spark telling me I've made it to the sputter on the back of the gator edge. I have sharpened a couple friends' "wavy" blades and I have to use the roller end for most of that.


----------



## MMoore (Aug 8, 2018)

Dkrem said:


> MMoore said:
> 
> 
> > how are you doing the profile of the blade?
> ...


yeah ok. my round end is a 4" radius so it just doesn't work to fit into a "wavy" blade.


----------



## Dkrem (Mar 16, 2019)

I think my rollers are 3" dia so they usually just barely fit, or I can work off the side of one of them and make it work.


----------

