blade straightness

Discussion in 'Mechanic and Repair' started by BZB_Helpers, Apr 14, 2007.

  1. BZB_Helpers

    BZB_Helpers LawnSite Member
    Posts: 131

    I have a set of high lifts that the tips bend down about 1/4" when using a straightedge from tip to tip.
    What is the max limit?
    Does this effect cutting performance?
  2. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Posts: 1,164

    I would think this would be within limits, This is a good reason for blade balancing on single blade mowers. Think about the weight of those high lift wings on the end of that blade and what that blade is doing spinning on a single center fixed point(crank shaft)off an engine running 3600 rpms. I would think that blade is going to level off from the centrifugal force. But maybe some else has better insight on the subject.

    Hope this helps:)
  3. mini14

    mini14 LawnSite Member
    Posts: 236

    who really cares, no offense...blades are the least of my business worries.
  4. TLS

    TLS LawnSite Fanatic
    Posts: 7,937

    Most blades DO have a slight bow from the factory.

    This is normal.
  5. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Posts: 1,164

    Well then, thank you for that bit of info :rolleyes:

    I would think that running a lawncare business that the blades would be a large part of the business. With quality of cut being of the utmost importance,
    But its your business and you should run it as such.
    Good luck
  6. BZB_Helpers

    BZB_Helpers LawnSite Member
    Posts: 131

    I was just wondering because I have new exmark mulching blades that are perfectly straight but these blades came with my machine that i bought used.
  7. khouse

    khouse LawnSite Bronze Member
    Posts: 1,465

    I have had people bring in a mower telling me that it hasn't cut good all season. I look under the deck only to find a blade badly bent. Bent so bad that the cutting edge wasn't facing forward. Or the blades installed up side down. I don't think a business would get much repeat work with blades so bad. When you run really dull blades you tear the grass where the grass turns really brown on top. You can hear and see the difference with newly sharpened blades.
  8. Mark in MD

    Mark in MD LawnSite Senior Member
    Posts: 322

    This is good info.

    I always wondered why the manufacturers gave us funny looking blades like that. I've been using flat blades for decades. BUT -- what will happen is the deck of your mower will eventually become warped. An almost-invisible bubble will appear in the middle of the deck. I always thought it was a result of bad spindles and age, but maybe running straight blades for so many years also added to the problem.

    When the deck warps, the blades won't spin horizontal to the ground, nor will they spin on the same plane as each other. For example, the left edge rotation of the blade will be measurably higher than the right edge rotation of the blade. Major headache. I've found what you can do is remove the spindles and add spacer washers on the bolts between the spindle housings and the deck. Trial and error to figure out how many spacers you need. But this will correct the problem.

    Or, you can go buy a new mower. :)

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