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new "blade length" therory?

metro-hp_48

LawnSite Senior Member
Location
TN
Thought I had heard it all, and would like to see how many here, would agree with this (MTR's) therory;

"yes sir, it goes like this...a 36" cut nicer than a 32" and a 52" cut even nicer than a 48". The width and length of blade provide a smoother cut, and of course the stripe, can you beat a stripe of a 52" Z or a 52" hydro WB? never."

Any thoughts on this from anyone else?
 
OP
metro-hp_48

metro-hp_48

LawnSite Senior Member
Location
TN
I myself say it would depend more on deck design, blade type, tip speed, speed of mowing, type of grass, ect. I may be all wrong, but that's just my theory. Width and length? hmmmm.
 
OP
metro-hp_48

metro-hp_48

LawnSite Senior Member
Location
TN
That's the way I took his theory, Richard. Makes no sense to me, either. Maybe he can explain in more detail.
That I have to hear.
 
The biggest difference I've seen is the longer the blade, the more difficult they are to keep in alignment.

Dave
 

LawnMower

LawnSite Senior Member
Location
Newport RI
Originally posted by metro-hp_48
Thought I had heard it all, and would like to see how many here, would agree with this (MTR's) therory;

"yes sir, it goes like this...a 36" cut nicer than a 32" and a 52" cut even nicer than a 48". The width and length of blade provide a smoother cut, and of course the stripe, can you beat a stripe of a 52" Z or a 52" hydro WB? never."

Any thoughts on this from anyone else?
I don't think its the length of the blade. Its the length of the deck. You could have a 61 inch deck with 5 small blades in there, and would still give a great cut.

Also the larger mower with large tires makes a difference too. Large tires ignore irregularities in the lawn. Wide decks smooth out irregularities in the lawn. Big mowers leave less wheal marks. All these things tend to make a smoother looking cut, I think.
 

barnard

LawnSite Senior Member
Location
central,OK
There is some truth to the blade length longer is better theory. Example given a 10 inch blade with a blade tip speed of 20,000 rpm 1 inch in from the tip the speed of the blade is 20% sloweror 16,00feet per minute 4 inches in the speed is 80% slower or 4,000 feet per minute.The distance from blade center to tip is 5 inches. Now take a blade20 inches in length. 10 inches fromcenter to tip. The blade speed is 10% less per inch from tip. 1inch from tip blade speed is 19,000 4 inches from tip blade speed 12,000 vs. 4000 for the 10 inch blade. It is a factor in the cutting performance of the blade because not all cutting is done at the tip.If it were blades wouldn't be sharpenend 4or 5 inches. just the last 1/2 inch would. In general longer blades cut better but if you took your 48 inch walk behind and it had two 25inch blades instead three 17 s thedistance between front and back wheels would have to be increased by about 8 inches. Moreso on a 61 inch cut . this would mean more scalping and less manuverability . There are many trade ofs in deck design. If shorter were better given the competition in the industry some manufacturer woul be putting 4,5 or six blades on there decks.
 

DLCS

LawnSite Platinum Member
Location
Illinois
Originally posted by barnard
There is some truth to the blade length longer is better theory. Example given a 10 inch blade with a blade tip speed of 20,000 rpm 1 inch in from the tip the speed of the blade is 20% sloweror 16,00feet per minute 4 inches in the speed is 80% slower or 4,000 feet per minute.The distance from blade center to tip is 5 inches. Now take a blade20 inches in length. 10 inches fromcenter to tip. The blade speed is 10% less per inch from tip. 1inch from tip blade speed is 19,000 4 inches from tip blade speed 12,000 vs. 4000 for the 10 inch blade. It is a factor in the cutting performance of the blade because not all cutting is done at the tip.If it were blades wouldn't be sharpenend 4or 5 inches. just the last 1/2 inch would. In general longer blades cut better but if you took your 48 inch walk behind and it had two 25inch blades instead three 17 s thedistance between front and back wheels would have to be increased by about 8 inches. Moreso on a 61 inch cut . this would mean more scalping and less manuverability . There are many trade ofs in deck design. If shorter were better given the competition in the industry some manufacturer woul be putting 4,5 or six blades on there decks.

Ditto
 


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