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In a previous post someone mentioned that basically the more blades you run the lesser the quality the cut. Would someone shed some light on that. I have a Craftsman 46" 3 blade and think the cut is good.

Thanks.
 

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Deere 330 Killer
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i would tend to think otherwise. my 3 blade sears deck from 1974 cuts smoother and more level than my 1999 honda.
 

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I Love All Color Tractors
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I would think that the more blades present means more sharp cutting area and thus a better cut.
 

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Just my guess here, but I would think blade speed has more to do with the quailty of the cut than how many blades. A lot of the older three blade decks didn't have the blade speed of the newer GT's. I maybe should be saying blade tip speed here, not rpm's. The decks that do the best job seem to be a full floating deck. I converted two of mine and Dad's to full floating and they did a lot better of cut. Dad's was a two blade 38", mine are three blade 48" & 54", all of them gave a good cut.
 

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Deere 330 Killer
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also depends on how sharp the blades are, how fast/high you mow, etc
 

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I Love All Color Tractors
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Another good point about tip speed. Shorter blades will have a higher tip speed and will spin around to make contact with uncut grass sooner than a longer, slower tip speed blade.
 

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Where I notice a difference between my 38" 2 blade deck and 48" 3 blade deck is in turns. The 48" will not cut flat in a turn and I've tried all the setup by the book and tricks I know. The 38" will. Deck design, blade type (mulch or high lift or standard) and grass type all play in the cut quality game. But then, when you have pitiful sun baked brown crappy grass like mine, it doesn't really matter.:banghead3
 

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Just Have a Little Faith!
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Shorter blades will have a higher tip speed and will spin around to make contact with uncut grass sooner than a longer, slower tip speed blade.
Why do shorter blades have a higher tip speed??? Tip speed is only a function of sprocket ratios and if a short blade and a long blade had the same ratio, the long one would be faster.
 

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AKA Moses Lawnagan
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Tip speed is directly dependent on blade length and rpm. If you spin blades of two different lengths (diameters) at the same rpm, the longer (greater diameter) blade will have the higher tip speed, because it is describing a greater arc. The mfgs want to keep tip speed high for cutting ability/efficiency, but low so they are quieter. As the blade tips approach sonic speed, they start popping and get much noisier, plus the wear on the blade tips increases dramatically. It's a trade-off between efficiency and noise and longevity.

The other consideration regarding making a deck a one, or two, or three blade deck is the depth of the deck from front to back. Imagine how deep a 54" deck would be if it only had two blades (or just one !). If they were exactly parallel, it would have to be a minimum of 28" just for the blade travel. That would mean the deck itself would be 30-32" or more from front to back. In order to fit between the front and rear wheels of the tractor, with room for lifting and dropping, allowing the front wheels to turn, etc, the tractor wheelbase gets pretty long, which limits its turning radius, and the compromises keep on building.

I see some math whizzes thinking "hey, 28 inches x 2 = 56, NOT 54". The blades would have to overlap in order to not have any uncut area between them, also meaning they would have to be synchronized so they wouldn't hit each other. The alternative to that would be to stagger the two blades so there is an overlapped cut, but that would increase the size of the deck even more, the wheelbase would have to be even longer.....

So... the decks use shorter blades and more of them as they get wider and wider. The blade rpm (and therefore tip speed) is kept at the design limit by using different diameter sheaves for decks of different widths.

The quality of cut is determined by the stiffness of the deck, which maintains the alignment of the blades side to side and front to back, and having blades that are true and not warped or bent. There must be enough offset in the deck to allow each pair of blades to overlap their cuts, so as not to leave any uncut material between them.
 

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I Love All Color Tractors
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Sorry guys, I had a moment. :fing20:

Kevin is right about the tip speed. The longer blade would have the higher speed. I was thinking of the circumference of the circle that the blade makes while spinning.

The longer blade would have to travel faster for the tip to come back around to the same spot on the arc than the shorter blade would have to.
 

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I Love All Color Tractors
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I believe I was the instigator of the previous post when I said, " in general 1 blade cuts better than 2, which cuts better than 3."

I believe that to be true. I think I must have read it on the net somewhere, either here or GW or TBN, but it makes sense with my limited samples. My Toro recyler, 1 blade cuts better than my X304, 2 blades which cut better than my old 3 bladed craftsman.

I know that good quality decks of 3 blades, JD or Simplicity, will often cut better than lessor quality 2 blade decks, MTD or Murray, but I was speaking of decks of equal quality, specifically Husq./Dixon/Craftsman which all are made in the same plant.

In that case, you just have a better shot of getting the deck level with a 1 blade deck vs a 2 or 3. Which is why the old Snapper RER is still selling well, you just can't beat the cut of one of those 30" or 33" single blades.

steve
 

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I believe in all of the above except the math errors.:D I also think the aerodynamic design of the underside of the deck, whether 1,2 or 3 blade, makes a huge difference. I can see the difference when cutting in reverse (horrors!:D) as opposed to going forward with my JD 48C deck. Going in reverse cuts grass better and mulches leaves better no matter which blades I have on at the time, Gators or OEM. My deck IS leveled properly within 1/8" as per the book.

Further proof to me is running a PowerFlow collection system. It is more efficient cutting and picking up in reverse. The blades cut the grass and it's carried around by the air to the already cut grass where it is not impeded in it's trip to the blower/chute. Going forward, the grass ahead of the blades seems to hamper the clippings going across the cutting action.

I further realize nobody else has the problems I've had with the design of this deck. Everybody elses cuts so good...:D
 

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Just Have a Little Faith!
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I have tried changing the deck sprockets until tip speed approaches the speed of light. Albert Einstien first did his research on a Lawn Boy. I find that the grass cuttings are transformed into a beam of plasma and disappear into the Twilight Zone. However, black hole formation is a dangerous possibility. Don't try this at home!:Stop:
 

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I'd say deck width has more to do with it than the number of blades. I've never seen a rider do as good of a job as a push mower(possibly make an exception for gang mowers), unless your lawn is absolutely flat. Mine is not. The narrower deck can more closely follow the contours of your lawn.

That being said, I mow close to 3 acres and I'm not gonna do that with a push mower.
 

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Albert Einstien first did his research on a Lawn Boy. I find that the grass cuttings are transformed into a beam of plasma and disappear into the Twilight Zone. However, black hole formation is a dangerous possibility.
Um, in this case... shouldn't that be a "green hole"...? Or doesn't it antimatter?:D


My FIL had one of those old Sears 30" single blade riders with the engine right under the seat. That thing mowed the lawn like a carpet as long as I kept the blade sharp. My 30" Gravely w/X-ed blades would do the same thing at less RPM (I believe). The best cut I've ever gotten was with my Snapper walk behinds and I compare all of my tractor results to that. None compare.
 

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When I rebiult the 48" deck on my 1650MF the owner of a lawn mower shop (older fellow-my age) told me how to set the deck wheels and center rollers and to make it full floating. I did that to my MF10, Dad's MF 8, and my MF1650&1855 decks and they all gave a lot better of cut.
 

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Packer Backer
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The mfgs want to keep tip speed high for cutting ability/efficiency, but low so they are quieter. As the blade tips approach sonic speed, they start popping and get much noisier, plus the wear on the blade tips increases dramatically. It's a trade-off between efficiency and noise and longevity.
Approach "sonic speed"??? You honestly saying you have a blade tip speed approaching 750mph. LOL
 
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