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Thread: Sharpening Mower Blades?

  1. #1
    Join Date
    Mar 2003
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    Sharpening Mower Blades?

    How do you do it? I need to get better about doing it. It seems like the bench grinder works the worst for me--overheating, uneven, etc. Using a flap disc on an angle grinder seems to work OK. It seems like a belt grinder would work best if I could find a decent 1" wide machine but most are way underpowered.

    How do the pros do it?

    Edit: I'm talking about the very heavy 21" blades my ZTR uses. Very much like the ones my 60" belly mower used to use.


  2. #2
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    The pros often have a jigged machine to do it, with a front bevel and a back bevel set (i guess some do the back bevel by hand). Youtube it, and you can see people trying to sell the machines.

    I do my 21" blades by hand on the bench grinder (in a pedestal with plenty of room around it) and then finish the edge off with a file and file on a back bevel for edge strength.

    It's important to have a balancer, either make one or buy one for about $5 or whatever they cost.

    If I were using an angle grinder, i'd use a flat disc instead of a flap disc.

    ( a kalamazoo 1x42" grinder do them fine, too, as long as it had a fairly coarse belt on it).
    Last edited by David Weaver; 05-10-2012 at 11:03 AM.
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  3. #3
    I actually use my worksharp to sharpen my mower blades. It works great.

  4. #4
    I use a Dremel with a sharpening/grinding stone (both the bevel and flattening the immediate back of the edge) and then go over each side with varying grades of the small sand paper tubes (course to fine of course.) I kind of thought about it like sharpening and then honing plane irons.

  5. #5
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  6. #6
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    I use my belt sander. I have a belt I use exclusively for sharpening my mower blades. I put it in a vice and have at it. Easier to hold the correct angle this way. It is also easy to check balance. Drive a large nail into a wall and put the blade on it. Hold it horizontal to the ground. If it stays put, it is in balance.

  7. #7
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    I use a drum sander chucked up in the drill press. It doesn't burn the blades, and gets them sharp.
    Works great to get the flat on the back of the blade.
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  8. #8
    As easy as it looks to get to the blades on that mower, I'd hit them with a file every few mowings. You'd only need the grinder if you were mowing rocks and foreign objects. The method matters less than the balance. It would be difficult to affect the balance with the file. We use one of these to check balance but a steel rod or screw driver should be accurate enough.
    I make dirt out of woodworking tools.

  9. #9
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    Check with your manufacturer. My Honda push mower service manual recommends that I only sharpen a single bevel (versus both sides) and then they recommend that I break the edge with a file (i.e. no longer super sharp). Supposedly this helps prevent the blade from chipping when you hit a hard root or rock. I check the balance with a thin screwdriver.

  10. #10
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    There does end up being a lot of foreign material in my yard--sticks, stones, etc. And we've got very sandy soil which just sandblasts the blades. So I think even with frequent sharpenings I'm still really looking at more of a grinding option.

    I looked up some commercial grinders. I could fabricate something like those real easy...


  11. #11
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    I hit the blades lightly with a hand grinder without removing the blades the last time
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  12. #12
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    If you have a bench grinder that has free lateral access (like the motor is behind the wheel diameter laterally), you could easily make a fixture to lay the blade in on a bench grinder and pull it through.
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  13. #13
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    I have always used a bench grinder to sharpen my mower blades without issues. I did have to replace the blades once because the sand in my yard wore off the back lifting edge. I cut grass at a large public facility once where they had 15 or 20 mowers. The mechanic there had to sharpen a half dozen or more blades a day. He just used a regular bench grinder.

  14. #14
    Quote Originally Posted by Matt Meiser View Post
    There does end up being a lot of foreign material in my yard--sticks, stones, etc. And we've got very sandy soil which just sandblasts the blades. So I think even with frequent sharpenings I'm still really looking at more of a grinding option.

    I looked up some commercial grinders. I could fabricate something like those real easy...
    You certainly could build one. My grandfather made a custom blade grinder about 50 years ago. It works perfectly to this day. The blade rest is a piece of wood cut to the give the right grind angle laminated with a sheet of brass. If I had to guess, it is probably turning at ~900 rpm with a 1750 rpm motor and about a 2:1 pulley ratios.

  15. #15
    I use a large mill file with the blade clamped in a vise. I only sharpen a single bevel as that is the way the blades came from the factory.
    Lee Schierer - McKean, PA

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