sharpened blades

Discussion in 'Lawn Mowing' started by scorpioxx, Apr 17, 2008.

  1. scorpioxx

    scorpioxx LawnSite Member
    Messages: 32

    how many times can you sharpen blades b4 they bacome absolete?
  2. XterraJohn

    XterraJohn LawnSite Member
    Messages: 178

    I once took a blade in to be sharpened that had a hole through the section where the blade kicks up in the back to create suction. It was explained to me that after years of mowing, dirt and other material basically sand blasts away the metal, creating a hole.

    If nothing like this has happened to your blades, and they are not bent or otherwise damaged beyond reasonable repair, I imagine that you can keep sharpening them as long as there is enough steel left on them to maintain strength.

    Of course, I am no expert, so, I could be completely wrong with all of this... Sharpen at your own risk.
  3. jaybird24

    jaybird24 LawnSite Senior Member
    from midwest
    Messages: 623

    Not a clue- usually someone hits enough rocks to turn them into brush blades long before they would be used up. Makes me wonder though if by taking that much away from a blade would affect the cut. Less inertia from less mass, or if these machines don't really care whats down there?
  4. fatjack

    fatjack LawnSite Member
    Messages: 17

    Remember, as you sharpen blades THEY GET SHORTER! First signs are an uncut strip showing up where two blades used to overlap. We've had this "blades getting shorter" discussion before, and some folks still don't believe it; but remember the cutting length of a blade is measured on the diagonal from one sharp corner point to the other. As you remove metal by sharpening, this distance gets shorter.

  5. I sharpen them until the sharpened edge starts going up the sail that's bent up on the back side of the blade.
  6. KGR landscapeing

    KGR landscapeing LawnSite Bronze Member
    Messages: 1,544

    what they cost 5 bucks a blade so you sharpen them till you dont think they seem good then use them as paper weights
  7. Two Seasons

    Two Seasons LawnSite Senior Member
    Messages: 791

    They don't get shorter, they become narrower. If a blade has a rounded corner on the cut edge, remove enough material to restore the cutting edge to the original full length of the blade.
  8. fatjack

    fatjack LawnSite Member
    Messages: 17

    As I mentioned before, not everybody understands it at first; in fact the last time I brought this blade "shortening" up, I had to get a flame proof suit. But it's simple high school geometry. The cutting width of a blade is NOT its length, it's the DIAGONAL from sharp point to sharp point.
    Some manufacturers, I think Ferris was one, sold "radius cut blades" that were curved on the ends to match the blade diagonal. When you sharpened them, they stayed the same diagonal length.

    I know it seems like it wouldn't make any difference, but as you continue to sharpen blades, eventually the area where they should overlap will be gone leaving strips and stragglers. Really!

    FJ (looking for that suit again)
  9. Oldtimer

    Oldtimer LawnSite Bronze Member
    Messages: 1,459

    Everyone should listen to FatJack because he is correct.

    Blades aren't measured from end to end. Never ever allow the end of the blade to round off.

    You can lead a blind hog to water, but you can't make him drink
  10. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    Yeah but the real concern is fly-apart resistance, that is, you need enough STEEL in the blade so that IF you were to hit some thing solid like a water meter cover at WOT... When that happens you do NOT want the blade to come apart, so...

    As a rule I also sharpen them up to where the 'flat' part starts to raise up into the sail, but that IS too far gone... You decide but I get at least a year out of A set (of course I have more than that, but if all I had was 3 blades then I would get at least one year out of them). Once they get to that point where they are 'iffy' I keep them around for the occasional 'bush hogging' job lol

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