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Lawnmower Blade Sharpening Methods and Tips

lawnmower blade sharpening


josh deaven
May 01, 2012 09:23 AM
Nice write up!
    • Wayne195 said thank you
Thanks Josh; it's not as detailed as many of the other tech articles but I hope it can be helpful to someone.
josh deaven
May 02, 2012 11:30 AM
In this hobby there is always something to learn.We will never know it all.Always try to keep an open mind.
I'll be sharpening three of my blades today, so I will keep your info in mind. Thanks for the timely article.
I sharpened 4 blades a month ago and it was my first time doing this. Wish I had had the info on the 40-45 degree. I just did my best to follow the old edge and the end result is not satisfactory.

I will be getting to them blades again now and thanks to you ill know the proper sharpening angle.
    • 637Yeoman said thank you
I learned the hard way. It is a great investment to purchase a impact driver either electric or air. my wrench slipped off the last blade I was installing and I knuckled into the freshly sharpened blade. took a long time to heal and still hurts when it gets cold. BE CAREFUL!
    • oldedeeres and WH55 have said thanks
Great tips on sharpening blades. How do you get at them in the first place? My" olde deere" puts blocks behind the back wheels of the J.D. stx38, runs the floor jack under the front end and lifts 'er up. AND YOU'RE RIGHT. BE CAREFUL!
    • WH55 said thank you

That was a great idea.  I used that last year when I

sharpened my blades.  

As c50ge suggests an impact wrench is a good investment, especially if it's been awhile since the blade was removed. I'd reccomend either air or electric and the wood block and C clamp idea is a must when you're using a powered impact wrench. Otherwise the blade will spin and could cause a nasty injury.


Earlier this year a friend tried to remove a blade without an impact wrench and couldn't get the bolt to come loose. Instead the shaft turned inside the belt pulley. The combination of twist and hammering of the impact wrench eliminates this problem usually. Another thing to watch for is when you re-install the blade is to make sure you don't over tighten it. I used to work at a lawn and garden equipment repair shop and we found out the hard way about doing that on a push mower. A person using an impact wrench over tightened the blade bolt and when he test started the mower, the shaft broke and threw the blade out from under it. Fortunately no one was injured although the blade put a bad dent in the toolbox at the next work station. After that incident we started using a torque wrench  to tighten the bolt when we re-installed blades.


Harbor Freight has some reasonably priced click style torque wrenches which can come in very handy when performing engine maintenance.



I have sharpened my own as well as the States mower blade for many years.  I have never tried to hold the blade cross wise of the grinding wheel.  Every little movement up and down changes the angle and increases the chance of burning the cutting edge.  This softens the edge and it will nick easier.  I hold the blade vertical with the grinding wheel,k and even if moved side to side the angle does not change.  With a little practice it is easy to feel when you have the flat of the cutting edge of the blade against the flat of the grinding wheel.  Just my way of doing it that has worked for me for many years and the way I do it for customers.

For getting at the blades, I set a 10' pole in the ground at about a 25° angle.  Bolt through the top with a cable pulley attached and a hand winch about shoulder high.  Hook the tractor or deck with the hook on the end of the cable and lift it up.  Use the same set up for washing out the under side of the deck.  Battery impact is a must but clean the bolt heads off first.