herbenus
Gold Member
I'm missing the point about why this is important. Interesting maybe. But important?
Finish mower blade
- Thread starter nomad
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smilingreen
Silver Member
Ok..... I know a little bit about mechanical design. As it had been mentioned before, not all design and testing critera is released to the general public. Lets face it, what good would it do to release this info to the general public? I would say 95% of the public could care less about reading up on their mower blades. Of the the 5% of the people who do care, probably only 5% to 10% of them would even understand what the data even meant.
This doesn't inlude the fact that the blade design is "Patented" and the test info and design drawings are proprietary and confidential. I used to work for a large corp engineering firm for ten years. Everything we designed was confidential and proprietary. The drawings or test results never left the firm without strict confidentuality documents being signed by whoever needed that info.
It would be interesting to see your test results done on your supplied rendering. I am sure it probably failed. I bled on it a little.
This doesn't inlude the fact that the blade design is "Patented" and the test info and design drawings are proprietary and confidential. I used to work for a large corp engineering firm for ten years. Everything we designed was confidential and proprietary. The drawings or test results never left the firm without strict confidentuality documents being signed by whoever needed that info.
It would be interesting to see your test results done on your supplied rendering. I am sure it probably failed. I bled on it a little.
Attachments
herbenus
Gold Member
"We all have seen/read on the web sources that finish mower and espcially its blade and deck design is a complex technique - meant/implied that air flow around the blade is very important. "
Can you give an example website where they claim this. I'm not part of the "all" that have read this, but I would like to see it. A quick search and I didn't find one.
Thanks.
Can you give an example website where they claim this. I'm not part of the "all" that have read this, but I would like to see it. A quick search and I didn't find one.
Thanks.
Herbenus wrote:
</font><font color="blue" class="small">( Can you give an example website where they claim this. I'm not part of the "all" that have read this, but I would like to see it. A quick search and I didn't find one. )</font>
My mistake. I meant "web forums" like here rather than websites. Many people have been telling that how the blade and deck designs are so important/sophisticated in finish mowers because of fast air circulation inside. True that air flow inside the deck is important. But I am not feeling these blade designs are taking air flow details in details. Maybe, just a rough analysis.
Egon wrote:
</font><font color="blue" class="small">( Nomad: could you post your flow magnitude program. It might be fun to play with. )</font>
Egon, it isn't a programme (software), it is only a analyse of "order of magnitudes of Terms" in formulae. Just by looking at the boundaries/geometries and flow velocity and keeping these magnitudes/vortices/etc, it is easy to see "air flow" effects weren't taken into account (maybe, very roughly only - but recycling/re-cutting the grass requires detailed analysis.)
Junkman wrote:
</font><font color="blue" class="small">( Nomad....... please show us how you arrive at the facts that you tout..... )</font>
I can show in time - it's not easy to tell all story with a few sentences. I'll give a simple presentation after a real time flow analyse around the blade with some simple analytic simulations. Give me a month or two. I'm busy nowadays and really cold here;-) In the mean time, maybe, a major mower mfg participates to the discussion and can prove me I am wrong, who knows.
Chim wrote:
</font><font color="blue" class="small">( ... My simple experiment tells me the manufacturers could make more effective blades ... )</font>
Yes. but can they do? I will be questioning this after proving that they aren't designing the blades in details as their market people (like CCI) telling us.
Smilingreen, yes, this drawing I attached was only a draft version. So, the geometry isn't exactly same as the current blades for the moment. I'll repost it again when I finish drawing.
So -- why is this topic so important?? Well, it is - because most of manufacturers and especially independent dealers they sell their products of these manufacturers are blowing much especially when are telling the users somethings about technical things. This blade & air flow example is such a good/extreme example that they think they can blow easily. Why? Because air flow there in the finish mower is such a complex, a very chaotic/turbulent that you can blow/tell lie and end users will not easily see if they are telling truth or not. I mean - lets say a dealer comes and tells you that the mower he is selling has a special blade geometry that was designed to control turbulent flow around it, then you will probably believe him because you think your blade is controlling that flow too. I have seen many many people in other industries too who are blowing much when the flows are so chaotic. Maybe, this "technical blows" should be talked in a new topic.
</font><font color="blue" class="small">( Can you give an example website where they claim this. I'm not part of the "all" that have read this, but I would like to see it. A quick search and I didn't find one. )</font>
My mistake. I meant "web forums" like here rather than websites. Many people have been telling that how the blade and deck designs are so important/sophisticated in finish mowers because of fast air circulation inside. True that air flow inside the deck is important. But I am not feeling these blade designs are taking air flow details in details. Maybe, just a rough analysis.
Egon wrote:
</font><font color="blue" class="small">( Nomad: could you post your flow magnitude program. It might be fun to play with. )</font>
Egon, it isn't a programme (software), it is only a analyse of "order of magnitudes of Terms" in formulae. Just by looking at the boundaries/geometries and flow velocity and keeping these magnitudes/vortices/etc, it is easy to see "air flow" effects weren't taken into account (maybe, very roughly only - but recycling/re-cutting the grass requires detailed analysis.)
Junkman wrote:
</font><font color="blue" class="small">( Nomad....... please show us how you arrive at the facts that you tout..... )</font>
I can show in time - it's not easy to tell all story with a few sentences. I'll give a simple presentation after a real time flow analyse around the blade with some simple analytic simulations. Give me a month or two. I'm busy nowadays and really cold here;-) In the mean time, maybe, a major mower mfg participates to the discussion and can prove me I am wrong, who knows.
Chim wrote:
</font><font color="blue" class="small">( ... My simple experiment tells me the manufacturers could make more effective blades ... )</font>
Yes. but can they do? I will be questioning this after proving that they aren't designing the blades in details as their market people (like CCI) telling us.
Smilingreen, yes, this drawing I attached was only a draft version. So, the geometry isn't exactly same as the current blades for the moment. I'll repost it again when I finish drawing.
So -- why is this topic so important?? Well, it is - because most of manufacturers and especially independent dealers they sell their products of these manufacturers are blowing much especially when are telling the users somethings about technical things. This blade & air flow example is such a good/extreme example that they think they can blow easily. Why? Because air flow there in the finish mower is such a complex, a very chaotic/turbulent that you can blow/tell lie and end users will not easily see if they are telling truth or not. I mean - lets say a dealer comes and tells you that the mower he is selling has a special blade geometry that was designed to control turbulent flow around it, then you will probably believe him because you think your blade is controlling that flow too. I have seen many many people in other industries too who are blowing much when the flows are so chaotic. Maybe, this "technical blows" should be talked in a new topic.
smilingreen
Silver Member
Ok, lets see, where do I start. I am a full time landscaper. We have 4 different mowers, with different blade configurations.
My first mower, a JD 757 ZTR, i usually run high lift blades on this unit. The deck remains the same. The high lift is caused by the tabs at the back of the blade. The more pitch you have in the back, the more vacuum power you have. This is necessary in thick, wet grass. I run these blades 85% of the time. If it is really dry outside and the earth is very dusty, I change to a medium lift blade. This configuration still lifts the grass, but being the grass is not as heavy, because it is dried out, I do not need the lifting force. It also, helps keep the dust down with less vacuum pressure.
On my JD HD45, it came originally with a high lift blade. But, I use this mower for pristine sod grass. So, I purchsed a Mulching kit, which blocks off the shute and each mowing chamber. The blades for this application have virtually no lift. The blades are flat and are shapened from the blade tip all the way to the center, close to the hub. This allows the grass to be cut, and recut many times without blowing it out of the mowing deck.
So, I have gone through this statement for what?? Well, I guess to say, sometimes you want a lot of turbulance inside your deck, to move the grass around after cutting and out of the deck quickly. If you want to mulch the grass, you do not want as much turbulance inside the deck. The turbulance is part of the process of mowing grass. You buy different blades with different turbulances (back of blade pitch) to match the type of grass you are cutting and the weather conditions.
So, by saying all of this, I hope you have discovered there is more than 1 type of mowing blade for a mower. It just depends on what your grass and mowing conditions are. Most of America does not realize you can get different types of blades for different conditions. I realize it, because we do this for a living and we require different types of blades when the grass conditions change. Thats why our lawns always look great when we are done mowing them, regardless of what time of the year it is. Check this out for yourself.
My first mower, a JD 757 ZTR, i usually run high lift blades on this unit. The deck remains the same. The high lift is caused by the tabs at the back of the blade. The more pitch you have in the back, the more vacuum power you have. This is necessary in thick, wet grass. I run these blades 85% of the time. If it is really dry outside and the earth is very dusty, I change to a medium lift blade. This configuration still lifts the grass, but being the grass is not as heavy, because it is dried out, I do not need the lifting force. It also, helps keep the dust down with less vacuum pressure.
On my JD HD45, it came originally with a high lift blade. But, I use this mower for pristine sod grass. So, I purchsed a Mulching kit, which blocks off the shute and each mowing chamber. The blades for this application have virtually no lift. The blades are flat and are shapened from the blade tip all the way to the center, close to the hub. This allows the grass to be cut, and recut many times without blowing it out of the mowing deck.
So, I have gone through this statement for what?? Well, I guess to say, sometimes you want a lot of turbulance inside your deck, to move the grass around after cutting and out of the deck quickly. If you want to mulch the grass, you do not want as much turbulance inside the deck. The turbulance is part of the process of mowing grass. You buy different blades with different turbulances (back of blade pitch) to match the type of grass you are cutting and the weather conditions.
So, by saying all of this, I hope you have discovered there is more than 1 type of mowing blade for a mower. It just depends on what your grass and mowing conditions are. Most of America does not realize you can get different types of blades for different conditions. I realize it, because we do this for a living and we require different types of blades when the grass conditions change. Thats why our lawns always look great when we are done mowing them, regardless of what time of the year it is. Check this out for yourself.
Junkman
Super Member
Dave...... any suggestion where to buy blades for a Kubota 60" mower that are of a good quality other than the Kubota dealer????
I thought the same things you mentioned above. There must be many different mower blade configurations out there like you said. This (existence of many mower blade) fits my theory. And I had asked people (in another thread) to take pictures of their blades and post them here if possible so that we could discuss more about the blades in details - ps: and I can make an attempt to find an optimum blade configuration which can do the works in different conditions including different air flow behaviours around the blades in their decks. So, you are aware and experienced finish mower user and I guess we understood each other better.
Egon
Epic Contributor
Yep; I'm aware of quible and guible and would still like to see the data and techinical processess required for flow analasis of a mower blade!!
Egon
Egon
</font><font color="blue" class="small">( Yep; I'm aware of quible and guible and would still like to see the data and techinical processess required for flow analasis of a mower blade!!
Egon )</font>
Data = mower configurations/geometries and their physical quantities like their speeds. - I too would like to see that data set for different mowers.
Technical process for flow analyse =
I have never done any such a mower blade study, but can easily say that mower manufacturers are most probably using mostly computational techniques such as digitizing the flow around the blade into very small finite volume elements and running processors of their computers to solve the simplified fluid flow equations (simplified from Navier-Stokes eqns.) on these very small finite volumes if they are really doing such analysis. 3-dimensional mower blade surface will be the immersed body boundary surface that will be an input or an output of such a computational programme solving digitized equations/formulae over the finite (very small) volumetric elements of the air around the blade. If these manufacturers are trying to analyse the flow in very details by using very small volume elements of air as it requires to analyse all behaviours in the air, then their computers have to run for days, maybe even months. To reduce this computational time, they have to find the symmetric behaviours in the air flow around their blades. Here, computational scientists invite a pure mathematican to study their simplified analytic formulations (derived from Navier-Stoke formulae which are a formulae set of fluid flow following deterministic approach and hence formulaes which represent all flow behaviours in all space and time.)
Anyway - my first work is not to design a blade from zero. First thing to do in such a study is to analyse flows around the different blades. If there is any blade among them that fits doing the desired work, then the study stops and everybody buys this blade. If not, then the next step is to design a new blade with a proper configuration which will create "required" air flow behaviours in the deck.
Ps: by the way, what does "guible" mean?
According to Webster dict., "guib" means "a kind of antelope" - so, guible = guib-able ? and its meaning?
Egon )</font>
Data = mower configurations/geometries and their physical quantities like their speeds. - I too would like to see that data set for different mowers.
Technical process for flow analyse =
I have never done any such a mower blade study, but can easily say that mower manufacturers are most probably using mostly computational techniques such as digitizing the flow around the blade into very small finite volume elements and running processors of their computers to solve the simplified fluid flow equations (simplified from Navier-Stokes eqns.) on these very small finite volumes if they are really doing such analysis. 3-dimensional mower blade surface will be the immersed body boundary surface that will be an input or an output of such a computational programme solving digitized equations/formulae over the finite (very small) volumetric elements of the air around the blade. If these manufacturers are trying to analyse the flow in very details by using very small volume elements of air as it requires to analyse all behaviours in the air, then their computers have to run for days, maybe even months. To reduce this computational time, they have to find the symmetric behaviours in the air flow around their blades. Here, computational scientists invite a pure mathematican to study their simplified analytic formulations (derived from Navier-Stoke formulae which are a formulae set of fluid flow following deterministic approach and hence formulaes which represent all flow behaviours in all space and time.)
Anyway - my first work is not to design a blade from zero. First thing to do in such a study is to analyse flows around the different blades. If there is any blade among them that fits doing the desired work, then the study stops and everybody buys this blade. If not, then the next step is to design a new blade with a proper configuration which will create "required" air flow behaviours in the deck.
Ps: by the way, what does "guible" mean?
According to Webster dict., "guib" means "a kind of antelope" - so, guible = guib-able ? and its meaning?
smilingreen
Silver Member
Junkman,
Hmmm, for a Kubota.... I guess the Kubota dealer. Maybe, you can find aftermarket ones on a website somewhere. I buy my blades from the Deere dealer. He stocks several different types for my model mowers. If he doesn't have a certain type, he gets them to me by 10:00 AM the next morning. And, he gives me 20% off, too! /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif
Hmmm, for a Kubota.... I guess the Kubota dealer. Maybe, you can find aftermarket ones on a website somewhere. I buy my blades from the Deere dealer. He stocks several different types for my model mowers. If he doesn't have a certain type, he gets them to me by 10:00 AM the next morning. And, he gives me 20% off, too! /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif
