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Understanding How Different Blades Function

Discussion in 'Lawn Mowing' started by JLH, Aug 30, 2005.

  1. JLH

    JLH LawnSite Member
    Posts: 103

    I am trying to get a better understanding of how different types of blades actually function.

    I have never had this explained to me, and I find it very interesting, which makes me want to try different types of blades.

    I have a Hustler Super Z 60 / 28 EFI with new style deck with fusion medium lift blade.

    The following reply was by gene gl to my previous post on the Hustler forum. Can you please explain further?

    -I have been experminting this season with blades also. As P&J said, any 21" flat blade with a 5/8" hole will work in a 60" Hustler deck. There is a differance between blades from different manufactures. You need to try different brands to see what will work best in your mowing conditions. The Fussion blade from Oregon Corp. has a "bent" sail that is 1.100" tall and distributes the clippings more evenly throughout the discharge opening, but not as far. I prefer a "stamped" sail because it discharages toward the front of the deck opening and has more "air" volume. I tried a Scag blade that had a .900" lift that worked good. I tried a Bobcat blade that had a 1.100" of lift that was OK but didn't have a good volume of air flow because the lift was short in length. Oregon makes a "high" lift for Ferris that is 3" wide and has a stamped sail that is 1.450" high. This blade draws as much power as running doubles. I have a 25 HP Kowie and I think it is maxed out with this blade. It will discharge 3 cuts over. If I had a 27 or 28 HP unit this blade would be my every day blade.

    1. Please explain how different heights of sail on a blade effect discharge.

    2. Does the height of sail create a turbulance under deck lifting grass before it is cut or only after it is cut?

    3. What is the difference between a "bent" sail and a "stamped" sail? I looked at blades today from several different companies and the sail on all blades looked like the bend of the sail was a smooth curve.

    4. Does the "height or the length" of the sail determine how far the clippings are discharged?

    5. What is more important, discharge distance or how fine the clipping are cut?

    6. Why does a taller sail create more drag against the motor.

    7. Why do the scag blades have a notch cut out in front of the sail?

    8. What is the accurate way to measure the length of the sail?

    Any other information you can give me about how different sails function would be greatly appreciated.

    The more you learn, you realize how little you know.

    Thanks for sharing your knowledge.
  2. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    The best piece of advice I can give you to begin with in this thread is to remember to ADD "Generally speaking..." to the beginning of each statement made here.

    This is because all you can really get in general information about blades.

    But general tendancies do not always apply. You see, decks and blades depend on each other and both the deck/blade combo depends on input at the spindle and ever changing outdoor conditions.

    With that said, no one blade is going to perform the exact same reguardless of the deck design it is mounted in, nor is the deck/blade combo going to perform the same reguardless of input at the spindle or outdoor conditions.

    So you can learn general information about blades so you can attempt to use your better judgement in blade selection. But it's still a trial and error situation at best. So it is good if you can network with others who run the same mower you do...
  3. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Now, I haven't read your other postings. So are you having a particular cutting issue you are trying to resolve or fine tune? I see you are in North Carolina and I am familiar with your deck design. So I am going to take a stab in the dark guess that you are having problems with clumping, build up, and clippings bridging across the rear of the discharge opening, ect...

    Am I right or totally off base?
  4. MarcSmith

    MarcSmith LawnSite Fanatic
    Posts: 7,157

    do down the road with your window down stick your hand out of the window PALM down....No drag moves throuh the air pretty smoothly. now turn your hand 90* with the palm facing front or back. This is called DRAG. It takes more engery to keep your hand in place.

    Now your blades will generate a certain amount of lift, kinda of like a fan or a propeller. this lift will help Suck the grass UP straight to get a better cut at the same time if you have a side discharge deck you have created an area of high pressure under the deck and as we all know pressure want to equalize and with the opening in the deck the resulting air is forced out.. with the clipping and the morning newspaper you just ran over...:)

    Bigger sails, more drag maybe better discharge/cut. the finer the cut, the less likely you are to have mow over something twice or do some extra blowing to disperse teh clippings. With a blade the blows 3 cuts over would be a bothersome in that your runningt he risk of getting more clipping into places you really don't want them.

    Id rather have a fine cut, but not mulch, and still have a bit of discharge...
  5. JLH

    JLH LawnSite Member
    Posts: 103

    I am not having any problems at all. The stock fusion blades that Hustler is using with the new deck design are working fine.

    I was just interesting in learning how other style blades function.
  6. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    Good then... I'm currently keeping my eyes peeled for more Fusion blade offerings from Oregon. The 21" hustler blades would work on my mower, but my center hole is 3/4" instead of 5/8".... Until then, I will continue to be truely amazed with the durability of the Marbain cutter blades I'm currently using.

    Anyways, I wanted to ask, since you have the new discharge opening on your Hustler, have they now added any sort of kicker or director at the rear of the discharge mouth like most mowers have?

    I ask because I have been playing with that style.... _/ l ....discharge opening since trying it on the Chariot LX Gen. II style deck. Discharge was great with no kicker, which I feel would be extra good for an OCDC setup. No kicker there to obstruct flow.

    But, while side discharging, I get a bridging of clippings on the rear lip that comes off as a clump eventually. So I'm trying to decide if it's possible to make it work with no kicker... as in I need to experiment with more blade styles, or open or close the rear section of the opening design...
  7. Envy Lawn Service

    Envy Lawn Service LawnSite Fanatic
    Posts: 11,062

    As for blade styles in general, there are several that fall into these catagories...

    Low, medium or high lift design.

    These come in the following lift foil styles...
    Notched foil- blade is notched at the inside of the lift and the whole foil is a consisant angle.

    Soild foil- the lift foil is stamped and has a rounded contour on the inside of the foil.

    Teeth foil- such as gators, raptors, ect... and these teeth are directional. Some have inside flow like gators and raptors, while others have opposite angled teeth for outside flow and are often referred to as reverse gators, ect. Teeth style also varies from pointy like gators to squared off like raptors.

    Contoured mulchers- these have a contour ~ to the blade. Some step down like your Hustler blades do, while others are arched in the middle, depending on rather the application is a straight blade setup like most, or a formed setup like Hustler, Bob-Cat, Grasshopper, Lesco/Cub... In this contour they have the lift foil on the end, but also have a down discharge section in the formed area closer to the center.

    How each type of blade performs really depends on the deck it is mounted in, the input speed, discharge opening or mulching kit and outdoor conditions. This is very strongly evidenced by how some guys love Gator blade performance while others loathe it. I have found I like them on some mowers and hate them on others...
  8. gene gls

    gene gls LawnSite Gold Member
    Posts: 3,213

    What are you running for a mower? I think the front shape of the deck has a lot to do with the discharge. The less "vee" shape the better and more space between the blade tip and the front of the deck for flow travel. My 62" Walker deck has a lot of space and with low lift blades(OEM) it has very good discharge. My 60" Hustler deck has only about 1.5"....I added a " kicker" plate ,as you call it. Exmark uses it on thier deck for side discharge. Some days it works better than others.

    Email me your mailing address and I will fix you up with a set of Fussion blades to fit your spindles.

  9. JLH

    JLH LawnSite Member
    Posts: 103

    I don't understand what you mean when you say " kicker or director at the rear of the discharge mouth like most mowers have."

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