Lawn mower blade sharpening

B

BillL

Joined
Jan 12, 2005
Messages
239
I bought a Lansky wedge shaped sharpener supposedly for lawn mower blades. I have an electric lawn mower and today is the first time the blade got sharpened after 12 years of use. How sharp must the blade be, like when do I need to stop sharpening. I stopped after about 10 minutes, but the blade is nowhere near knife sharp.

Thanks
 
a dull lawnmower blade will tear the grass instead of cutting it. the torn tip will turn brown. i would get it as sharp as you possibly can but it doesnt need to be shaving sharp.
 
I've never used anything but steel files to sharpen a lawnmower blade and I've never wasted more effort than needed to get them as sharp as a machete and the grass is always greener on my side of the fence.
 
I owned a commercial landscaping company for 8 years and always sharpened my own blades. If you get them too sharp, they will chip every time you hit a stick or rock. You want them a little more than machete sharp because the blades dull much quicker due to the high speed. I would say about half way between machete and razor sharp to keep it cutting and not tearing the grass blades. Hope this helps!:)
 
There is no fixed amount of time involved in sharpening. It is sharp when your bevels reach the edge at a reasonably accute angle. If I had to guess I would expect it to take 10 minutes for each of those 12 years if you use a manual stone (2 hours or longer). I would use a grinder or belt sander to get the blade back into shape before starting with that hand stone. You could use a large coarse file, but that might take you close to an hour. After 12 years I would be looking for power tools.
 
I did mine recently with a big bastard file. The edge had some dings, but I just filed straight across until everything was smooth and sharp. It still had some dings and chips I couldnt get out, but the overall blade was shaving sharp.

I didnt go any finer than the file. I felt that hey, it's a lawnmower blade. It's not going to the blade show, and if it's sharp enough to shave hair, it's more than sharp enough to cleanly cut grass at a super fast rpm.

I discovered that lawnmower blades seem super soft.... Am I wrong?
 
psycho78 said:
I did mine recently with a big bastard file. The edge had some dings, but I just filed straight across until everything was smooth and sharp. It still had some dings and chips I couldnt get out, but the overall blade was shaving sharp.

I didnt go any finer than the file. I felt that hey, it's a lawnmower blade. It's not going to the blade show, and if it's sharp enough to shave hair, it's more than sharp enough to cleanly cut grass at a super fast rpm.

I discovered that lawnmower blades seem super soft.... Am I wrong?
Click to expand...

I haven't seen any one write about balance. You could damage your motor/engine irrevocably from the vibrations and stresses to the shaft if both sides aren't sharpened for balance aswell.

As to the blades being soft; they have to be so damage to said blade, engine/motor, person mowing or anything/one within say 100 feet or so if the blade were too hard to absorb the shock of hitting unknown objects.

They do harden/temper beautifly for knife making purposes though. :)

Jim L.
 
Thats why I didnt want to hog off any steel, and try to get out the chips. I knew I MAY mess up the balance. I just felt that since the blade is moving at a high rate of speed, it didnt need to be pretty and polished razor sharp. I just filed it enough to get a nice smooth edge so it would actually cut the grass instead of knock it down.
 
I use a fine stone wheel, and for balancing, a nail hammered into the wall acts as a pivot. It will tell you when you're balanced.
 
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