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Sharpening with angle grinder

Discussion in 'Lawn Mowing' started by Expert Lawns, Aug 6, 2003.

  1. Expert Lawns

    Expert Lawns LawnSite Silver Member
    Posts: 2,660

    I just bought an angle grinder to sharpen my blades with. There has been a lot of talk about sharpening and i'm hoping that this method is better than my bench grinder. Is there a certain way to use the angle grinder? I know some of you use a vise. does this help to keep a good edge and angle on the blade? does it still heat up the metal like a bench grinder?

    Basically i'm looking for a better method to sharpen my blades with rather then spending money at the local mower shop, using my bench grinder or emptying my bank account on a Magna Matic. Thanks.

  2. MOW ED

    MOW ED LawnSite Fanatic
    Posts: 5,028

    I use an angle grinder. I put the blade in the vise and sharpen. Whatever you do, don't let the metal turn blue. That is easy to do if you stay in one spot too long. I always go back and forth.
    I use a blade balancer as I finish up. Try and make sure your blades are clean.
    I know its no comparison to the Pro sharpeners (which I would love to have) but its a better option than the bench grinder of hand file.
  3. xi_bowhunter

    xi_bowhunter LawnSite Member
    Posts: 56

    I use an 4 1/2 inch angle grinder with 50 and 80 grit sandpaper and have had good luck. doesn't seem to "grind" the blade away so fast.
  4. DLCS

    DLCS LawnSite Platinum Member
    Posts: 4,378

    I use a 4.5" angle grinder with a flap style sanding disk. I used to use a bench grinder but this way is easier to get a very sharp edge. Also, I have found that its harder to over heat the blade with a sanding disk rather than a stone wheel.
  5. Expert Lawns

    Expert Lawns LawnSite Silver Member
    Posts: 2,660

    Thanks guys. one more thing, does the angle grinder method help to keep the factory angle on the blade? i noticed that after using the bench grinder, my blades have really lost their natural look (angle). they are almost rounded right now which i know isn't good. i get just enough edge on them with the bench grinder to last about a day
  6. DLCS

    DLCS LawnSite Platinum Member
    Posts: 4,378

    I've found that I can hold the angle better while using a angle grinder. I too had a problem maintaining the factory angle with a bench grinder. Best thing I did was when I stopped using that bench grinder. So much fast with a 4.5" angle grinder a flap style sanding disc.
  7. MOW ED has the technique.
    I might add a little to that.
    The more sparks you see fly the cooler the metal stays. Because the heat is leaving with the sparks.
    I also soak the blades in a bucket of water before sharpening. It seems to keep them cooler. Maybe just because they're wet.
    If you don't want to keep demounting the blade from the vice to soak it in water, use a sopping wet rag to cool it.

    Keeping the proper grind angle makes a big difference in how long blades last between sharpenings.
    I'd been keeping mine way too sharp of an angle. Even the aftermarket blades came with too narrow of an angle.
    Toro recommends 40 degrees for my machines.
    I bought a adjustable square from Harbor Freight like this one:
    Though I bought mine on sale for a buck. It's just a cheap little plastic thing.

  8. sdwally

    sdwally LawnSite Senior Member
    Posts: 385

    A lot of our operators use a angle grinder to dress(sharpen) blades on the machines. If they can't get good access, then they remove them and use a vise.
    Various problems using this method, blades not balanced(increased load to spindle bearings), wrong or inconsistant cutting angle, and/or sything(cutting edge curved not straight). If our shop sharpens the blades, we use a bench grinder and a Magna-matic balancer.
    However you sharpen blades, practice and lots of repettion improves your skill and reduces time to do the task.

    As my Grand-Papie use to say, "There's more than one way to skin a cat!"
  9. geogunn

    geogunn LawnSite Gold Member
    from TN
    Posts: 3,010

    I used an angle grinder with good success untill the cheapassed thing burned up.

    I found that clamping the blade to the trailer top rail with a c-clamp made a perfect place to sharpen the blades.

    you want to move the grinder back and forth quickly to avoid getting the blade too hot.

    and, as always, balance!

    DAVE--not to argue but this doesn't seem right...

  10. Gravely_Man

    Gravely_Man LawnSite Silver Member
    Posts: 2,076

    You gentlemen are much better at this then I am, as I cannot get a very good angle with an angle grinder. The only thing that gets sharpened with the angle grinder are blades for the 6' bush hog.


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