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An idea on double blades

Discussion in 'Lawn Mowing' started by toddnks, May 20, 2007.

  1. toddnks

    toddnks LawnSite Member
    Messages: 34

    Acreage owner here, so you pro's might not be interested, but then again you might, as I mow alot of grass.

    I run double blades off and on on my M72, and my 3260 (Antique IH deck on a small farm tractor.) but not on our JD 430.

    Today while I was changing blades on the M72, I accidently picked up a blade for the 3260, the blades look about the same except for they are shorter, and I got to wondering if you could run a shorter blade or the same length blade over the spacer, to improve vacume, and give a high second chop effect.

    I didn't mount them that way, but was wondering if someone else might have thought of that, or tried it. I think it would help, but don't know.

    Also has anyone ever used a shorter blade as thier doubled blade?

    We mow about 25 acres of ground that used to be pasture weekly, so I just about every week have to change the blades, and I alternate between doubles and singles due to the time it takes to sharpen them and the time I have.

    Thanks in advance for any assistance you give.
  2. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    Yes, you can run a shorter blade up top.

    And you can place it anywhere up there, provided the cutting tip is above the full length blade.

    It's been done and the results have been good.

    Now a question for you...
    You run doubles on a Cub M-72?

    The way you type it, it seems like you put one on the spindle, then the spacer, and then the other blade?

    Also, for me, doubles have never really crossed my mind on the 60" I have.
    But now that I think of it, my thru-bolts aren't long enough to make me feel OK about it if I were to try it.

    Have you changed your through bolts or your stock spacers?
    If so, where did you get them from?

    3/4" stuff is not easy to find.

    Keep up with me on this, because I have something you are going to want to try.
  3. toddnks

    toddnks LawnSite Member
    Messages: 34


    Thats the idea, but I have not tried it yet.

    I have more bolt left (threads etc) with doubles on the M72 than I do on the 430 JD with singles on, so I have always thought it should be pretty good. Your bolts should not be, but could be shorter. The bolts on the 3260 are close to the same if not the same.

    No, I have thought of changing the spacers because I would like to be able to cut about 1" higher at times. Adding 1" to all my increments would be very nice.

    I have yet to look for anything that wasnt available at my local farm store. The only thing that I have had an issue in finding is blades for the 72. The JD 60 blades are cheap (very thin, and narrow), and can be purchased at TSC, the 3260 blades can be bought at the local farm store, but you have to take a blade with you, or you won't match them up very well. Bolts and spacers are available there as well, the last time I lost one on the 3260, I took one of the others off, and just matched it up.

    My in-laws own a excavating company, which helps in finding odd bits for equipment, and the fact that we have a pretty good machine shop, helps in fabricating many different parts.

    Will do.

  4. Mark in MD

    Mark in MD LawnSite Senior Member
    Messages: 322

    I don't understand. What is the advantage of running a shorter 2nd blade? Why not run a normal sized second blade?
  5. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    The main one would be less drag.

    The next would be having the lift wing closer in towards the spindle.
    (in theory, more chopping action)
  6. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087


    Your bolts must be longer than mine I'd say.
    I'm going to cross the part numbers between the 60" and 72" to see what I get.
    If those are longer, I'll just get a set of those.
  7. Wells

    Wells LawnSite Member
    from SLC UT
    Messages: 0

    I run two Fusion blades that are both the same lenght with a double blade kit. I've had great results with this configuration and don't really see how a smaller top blade is going to increase the overall cut.

    Here are some pics of my configuration. You will notice the doubles kit that looks like a chanel for each blade to slip into.

  8. Wells

    Wells LawnSite Member
    from SLC UT
    Messages: 0

    Here's another pic that shows the blades off of the chanel so you can see the double kit better.

  9. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Messages: 11,087

    That's the Gravely kit adapter thingy right?

    I wish I could get those with a 3/4" center hole.
    That's the ideal way to do doubles.
    That way they can never slip out of position.

    I'm going to have to break down and either find somewhere or get setup to drill out from 5/8" to 3/4". Somebody here once showed me that drilling bit to use to get it right. Just needs doing on a precision press I would think.
  10. BSDeality

    BSDeality LawnSite Silver Member
    Messages: 2,849

    I have run 21" blades with 17" blades on the upper deck before on my Gravely, It works as good as double 20's but its less strain on the clutch at start up. I've never used the gravely adapter, didn't even know they had it, I just bolt them into position with the air gun and they stay put unless you hit something really good. Then they can move.

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