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You Guys are wasting your time and grinding wheels

Discussion in 'Lawn Mowing' started by germann, Mar 7, 2003.

  1. germann

    germann LawnSite Senior Member
    Messages: 268

    Sharpening a blade from tip to center is a waste of your time and grinding wheel. Only the outer 1 inch or so, according to magna-matic, actually cuts. I still sharpen about 3 in., even on excaliber blades. Exmarks development of a blade sharpened to the center shows our ignorance. If you have a different understanding, pleas respond. Mabye someone who has done the speed of the blade at different intervals in could explain the physics.
  2. 1grnlwn

    1grnlwn LawnSite Bronze Member
    Messages: 1,261

    If your theory is corect then why does the bevel past the one inch dull just as fast as the outer inch. True that the fastest blade tip speed is at the outside portion of the blade. But how fast does it really have to move to cut a blade of grass. At half throttle won't it still cut grass? So at full throttle the blade will cut grass half way between the tip and spindle as equally effecient as the tips at half throttle. What about mulching properties? Not talking about closed discharge mulching, just the natural reduction of clippings gained by secondary cutting and double cutting in a back and forth style cut pattern. If the bevel was not cutting something it would not dull. If blades only had 1 inch shapened you would experience the following: Ragged cut at the higher speeds. More clumping of damp or heavy grass. Lost ability to mulch leaves and other debris.

    Ok I just went back and read your post again and have no Idea which side of the fence you are on. But I wrote all this stuff and by gosh I am posting it!
  3. Kent Lawns

    Kent Lawns LawnSite Senior Member
    from Midwest
    Messages: 870

    Oh, Okay.

    Everybody that's passed 9th grade geometry knows the closer to the hub the slower the speed and therefore less cutting action.

    PLUS, the time to sharpen blades is in removal, placing in vice or on wheel and re-tightening them. The few extra seconds to sharpen the whole thing is inconsequential.
  4. fatboy5803

    fatboy5803 LawnSite Senior Member
    Messages: 330

    You are correct on saying the cutting is mostly on the outer one inch or so, If you notice on the blades that can be sharpened on down toward the middle of blade, Feel it, the sharpened part. Is it as sharp as before you used it to mow?? It may be sharper than the one inch end.. It's to help mulch the grass or what ever you're cutting.... This is what I've noticed.,., Hope this has helped.

    Lou :cool:
  5. Gravely_Man

    Gravely_Man LawnSite Silver Member
    Messages: 2,075

    Agreed that the outermost 1" of the blade does most of the cutting but I am still going to sharpen the entire 3" bevel on each end of the blade. Is sharpening the entire blade going to do anything other then possible shorten the blade life? The answer would be no.

  6. FrankenScagMachines

    FrankenScagMachines LawnSite Platinum Member
    from IN
    Messages: 4,739

    The excalibur type blade (sharpened to center) is better for mulching and just reshredding clippings when discharging or bagging, but also alot of weeds are more stubborn to cut and require a blade like this. I have lengthened the cutting edges on my blades before to help cut weeds and they do work better then. As said already, yes only the outer tipe mainly cuts but some weeds do not get hit just then. This one weedy yard I have you can have a razor sharp blade and mow at 3" but still the weeds do not always get hit on first round. Sharpening the blades farther in helps on this type of property. Also like I said helps reshred stuff too.
  7. Wasting time and grinding wheels? Of course only the outer ends of the mower blades do most all of the cutting. So are they saying we should just sharpen the outer inch? How do they propose we do that?

    If you have a smooth transition from the existing bevel to the outer inch, then its going to develop an oblique angle. This would drive the blades of grass outward and away from the mower blade as it tries to cut, not good. Over time, the cutting tip would become severely angled away, effectively shortening the mower blade length leaving uncut strips. Additionally, an angled tip has an effectively slower blade tip speed, which would decrease the quality of cut.

    If you keep sharpening the mower blades parallel to the bevel, then you’re going to develop an offset. Not sure what that would do. But my guess is that the quality of the cut will suffer. Because the faster you’re traveling, the more of the bevel you’re using. I’d like to know what they’re getting at, and if they’ve tried what they’re suggesting, or if they’re just spouting theory.
  8. David Gretzmier

    David Gretzmier LawnSite Gold Member
    Messages: 3,645

    If I had my choice, a blade that cuts only on the outer 1-3", or a blade that cuts all the way to the center, I would choose the latter. if the outer 1-3" does not cut it, perhaps the inside would get it. at the very least, it has to help some.

  9. scott's turf

    scott's turf LawnSite Senior Member
    from NH
    Messages: 949

    Even if sharpening the blade to the center proved that it could cut the grass at this lower speed, any grass it did cut would be only the grass that passes near the center of the spindles. All the other grass would not be effected. I would think that the only benefit from such may be its mulching capabilities. Only a head to head experiment would proove this to me.

    LANDGUARD LawnSite Member
    Messages: 73


    Don't believe everything that a manufacturer tells you. If you think that it does not make a difference then do some test this summer and let us know your findings.

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