Finish mower blade

trkbldr · Jan 30, 2004

Junkman, take a look at mowproducts.com. I recently ordered blades for a 72" Woods finish mower as well as blades for an old Sears rider. The pricing is very reasonable. However, I can not give an opinion on quality as I have yet to use them.

nomad · Jan 30, 2004

I just visited the website given above (mowproducts.com) and searched the net for mower blades. So, there are so many mower blades out there. Why? or What gives?

Also, searched the net about mower blades and their technical reasonings on why they are designed so, but unable to find any detailed explanation yet. Just fyi. If anyone comes across such a web page, he/she can post here.

Molerj · Feb 3, 2004

I'm just wondering if you cut any grass or are just inquisitive? I have cut about 8 acres of grass for the last 10 yrs. & I haven't had that much interest in the aerodynamics of the blade. Heck, I've used probably 10 different riding tractors & twice that many push mowers over the yrs. /forums/images/graemlins/tongue.gif

txdon · Feb 3, 2004

Nomad, don't know if this is exactly what you are looking for but I found it interesting that they use a strobe light "to “freeze” blades for visualization under full dynamic conditions."

nomad · Feb 4, 2004

TxDon, I know Rover mowers - their products are mainly Walk-Behind and Ride-On Mowers - Their blades are like this given in this picture - I don't know if they are MFGing a 3-pt finish mower that we are talking about here.

I know also Gilmore Eng. and their "e3k" (from the net only of course.) Their this mower blade study, I suppose, is related to those lawn mower blades, not our 3-pt finish mower blades. I am emailing the web address of this thread to them now. If anyone from there to this thread comes and joins, he may enlighten us whether they also did somethings about our 3-pt finish mower blades.

As for their mower blade works; Rather than their stobe visualisations, I'd be interested in seeing their aerodynamic hot wire anemometry test details. For those who don't know about this technique; its principal is to measure the velocity using its relation to temperature/heat. So, this technique can also measure the turbulence (velocity fluctuations.) So, them Gilmores probably have the data of turbulence that we would also like to see in around our 3-pt finish mower blades. Okay, this data maybe a secret, but "similar studies in 3-pt finish mowers too were made" can be said in a public meeting (like we do here online

I believe Gilmores designed such blades taking also the air flow fluctuations/turbulences around their mower blades into account. (or, they only modelled the blades using cutting and lifting mechanisms and after the design, they measured/visualied air flow around the blade?) These two things are different; 1. designing an object/configuration without considering turbulent effects and then studying the turbulences around it - 2. designing a blade from zero according to a given flow type details including local turbulent regions. (2) is a really hard work. It's like that I will give you a painting (free hand, art painting) of a certain flow type with some special circulations/chaoses/turbulences in it and I'll ask you to design a blade which will create that flow type exactly. Why am I asking such a hard thing to be done by you? BECAUSE it has been claimed that "recyclings/re-cuttings a grass over and over" are being considered when designing these 3-pt finish mower blades AND to be able to that, you must do such a work (painting of air flow type - blade design) as I mentioned (2) that is a real hard work. And, recycling/re-cutting a grass blade over and over in the mower deck requires such a detailed hard work. I don't think Gilmores did such a study. Well, we'll see if anyone from there joins and tells us somethings.

Ps: my main goal in this thread is to talk about the finish mower details and also not to hear anymore about "air flow in general and re-circulations/turbulences in finish mowers are also being designed" - and to enlighten my farmer friends whose minds are confused by "some" manufacturers and by "some" dealers. No a generalized accuse here. Only "some", maybe /forums/images/graemlins/grin.gif

nomad · Feb 4, 2004

Another thing; I see Gilmores also did a noise study work.
Wondering what the noise level in decibels is permitted in the mowers. As far as I know, 120 db is critical for human ears - but, is there such a high noise level in the mowers?

rambler · Feb 4, 2004

Noise is dangerous to human hearing not on decibels alone, but on how long the exposure is.

As well, neighbors don't like loud machines next door to them so it becomes an issue of legislating politeness to the neighbors....

At one time 80 decibels was considered the max for longer-term hearing health. That may have changed.

As to the whirling blades, people like to have multching blades to chop up their lawn clippings, and so manufaturers made then to do so. How did they make them? Who cares. They just did.

--->Paul

RayHope · Feb 4, 2004

Hi All. Nomad emailed me asking to contribute to this thread. So here I go.

Gilmore Engineers is a consulting Engineering company. One of our repeat clients has been a local Lawn Mower Manufacturer in Australia.

About seven years ago, before I was working for Gilmore Engineers, Gilmore Engineers were asked to help with a performance problem that they were experiencing in Europe. The grass in some European countries was quite different to our grass, and they were not satisfied with the cutting performance.

We did quite a lot of work researching and testing (your are right, there is very little if anything published on this).

At that time we did some CFD (Computational Fluid Dynamics) analysis. This was limited by the software and computational power of PC's at the time.

We also did a lot of real testing of different blade shapes to see cut quality and also used clear mower decks to see what was happening.

The blade shape we came up with ended up cutting much better and also was much better at picking up and propelling the cut grass into the catcher. They named it the superior blade and now use it on almost all their models (not just the ones for Europe).

In the last few years we have worked on a noise reduction program. The EU has introduced noise restrictions for most outdoor machinery and these will be tightened further in 2006.

The main source of noise is the blades (we did tests to comfirm this). Software and computing power had improved leaps and bounds in the last few years and we were able to use CFD (Computational Fluid Dynamics) analysis much better.

Each blade model ran for almost a week (we needed a very fine mesh on the surface of the blades). We were able to compare the CFD results with actual noise measurement for the superior blade and a flat blade (which was much quiter, but no good for cutting and catching performance).

From the study we learnt alot about the flow around the blades and how this effects cutting and catching as well as noise. We were able to recommend some modifications to the superior blade which would reduce the noise enough to meet the 2006 requirements, and have little effect on cutting and catching performance.

New blades with these modifications have been tested and the noise reduction agreed very well with those predicted by our analysis.

Obviously all the results of the work are highly confidential and this is about as much as I can tell you.

We have not done any work on or for the Finish blades you are talking about.

Other work we have done includes improving the efficiency of Francis Turbines for Hydroelectric power generation and we are currently working on a project to generate power from ocean currents.

I hope this helps.

Regards
Ray Hope
Gilmore Engineers

nomad · Feb 5, 2004

Thanks for the contribution, Ray. I was expecting to hear some words from you and I got answers to some.

You say you have not done any work on or for the blades or our Finish mower. Our finish mower is less tech mower so I don't think there is such a study like yours about our finish mower.

( We did quite a lot of work researching and testing (your are right, there is very little if anything published on this). )

This (nonexistence/nonavailability of blade studies) was what I've been claiming. Since you did an extensive study you must have all publishments you were able to reach, or least you must have some research abstracts or, at least, you probably know from "verbal" sources who did what. Nonexistence/nonavailability of such works on mower blades which have been in the field for decades show that not much detailed studies on the mower blades. And, as I frequently said in this thread, very detailed studies are required to model the complex flow around the blade. I guess your blade (theoretical or analytical) model consists of the physical mechanisms of (1) cutting and (2) lifting the cut grass by propelling into the catcher. I mean you probably didn't include in the mathematical model of blade those complex turbulent local flows that will be very important for recyclying/re-cutting the cut grass several times (a process that's being claimed by someones here in our finish mower to be designed.) Since in your CFD studies you had to use a very fine mesh to study relatively simpler mechanisms (cutting the cut grass + lifting it to propel into the catcher), you people here, imagine how very very fine mesh should be used to study the flow details around the blade. Relatively "larger-scale" flow study like Gilmore Eng. did won't be enough to model that mechanism of recycling (re-cutting the grass several times.) - "Characteristic scale" that should be considered in such a theoretical, CFD and experiemental study of detailed air flow should be much less than the scale/size of the thickness of one thin grass blade in all flow region (not only boundary layer region) around the mower blade so that you can take small forces/effects in the air onto the cut grass blade which can move arbitrarily in the mower deck.

As a conclusion; As such a detailed air flow is REALLY hard work I'm sure about that there is no such a detailed study of recycling/recutting grass in our finish mowers. A model consisting of mechanisms of cutting and lifting the grass requires relatively larger scales (coarser mesh in CFD) and see (in Gilmore study as Ray said), even for such a larger scale study of theirs, they had to use very fine mesh in their works. Also, I believe they didn't use many many hot wires at the same time in their experimental studies - meaning that they didn't study "minor scales" or smaller scales in the flow. From what Ray says, I understand that their study is maybe most detailed study in the mower field- and imagine the other (finish) mower blade studies which are probably more coarser studies.

Ps: If I saw set of equations of your analitical model, I'd be sure about what mechanisms were taken into account. This should not be a secret to public in my opinion as scholars probably have such analitical models in their stores already. Maybe, I'm wrong. Maybe, you Gilmore and I together would do such a study

about our finish mowers by modifying your analitical model a little to include some smaller scales around the blade and we could produce a finish mower with a universal blade which will also do recycling/recutting works /forums/images/graemlins/grin.gif

Ok. Thanks for your contribution to this community forum.
Regards,
Nomad

Villengineer · Feb 5, 2004

Nomad, You are the spin master. The guy from Gilmore just confirmed or at least gave circumstantial evidence to support everything I pointed out was wrong with your opinion, yet you spin it as if it supported your assumptions. He stated that: 1) Despite your arguments that they weren't or can't manufacturers are in fact taking fluid flow into account when designing blades. 2) I told you why the work wasn't published and he confirmed that it's trade secrets. 3) He gave no evidence that they were not in fact doing analysis of other blade functions, yet stated that there was more but was unable to discuss it further.
How can you still claim to be right or that the same work isn't being done on 3pt finish mower blades? The fact that 1 engineering firm hasn't done the work for every blade or mower manufacturer doesn't prove anything. Companies like Deere have their own engineering staffs full of very intelligent and well equipped engineers assigned to their various products. They are better positioned do this work than a consulting firm which has to take up the assignment cold.

Egon · Feb 5, 2004

Nomad:

and to enlighten my farmer friends whose minds are confused

Me thinks the farmers are quite competent to distinquish between Quibble and Guible. Exspecially when mowing in a cow pasture.

Mayhaps you could update our Downunder friends with your Fortran programs. Should help them immensly on the turbine design.

Egon

nomad · Feb 5, 2004

Villengineer, somethings (technical things) may seem to you or to public to be trade secrets. But they may always not be so for some people like me. I mean... I mean if you know some basical things like designing a blade which will control small air flow "scales" around it is "almost impossible" by the technology today, then you would understand the real secrets in such studies like Gilmore did 8 years ago. What can be their technical secrets, anyway? There are some generalized formulae for the flow mechanisms and solid cutting mechanism between the mower blade and grass blade. These generalized equations are hard to handle unless you use super computers. So, Gilmore's only secret can be in the practical simple form of their empirical function they used as a term in a simplified solid+fluid equations. So, a set of equations with a "secret" term? No, I don't consider these equations as the secret things as such equations can be found everywhere. Solving them equations? Unless they use "special" numerical algorithms with some "special" tricks, I don't consider "solving process too is a secret" - See they are using Fluent and Phoenix(?) packages whose all solving methods are given to the public or to the owner of packages. Experimental study, use of hot wires, etc are secrets? No, they too are well known methods. Data output from computer solutions and data produced by experiments can be secret? Well, yes - but we see these data in their results (in the final blade design.) So, nothing actually is secret there. Anyway, you already have the blade they designed - Just take them, do some experimental and computational analysis and you can find all the data they obtained during the design process. Using a statistical analyse, you can even obtain a discretized form of their "secret" emphirical term that they used in simplified solid+fluid equations (if they ever used a term like an emphirical function in simplified generalized equations.) So, to me, there isn't any real secret in their studies. And, moreover, we are talking about completely different things; recycling/re-cutting the grass several time - As I often said, this requires a very complicated study that can't be done by the science today - and, knowing that this can't be done now is not a secret. So, at the best, re-cut the grass several times can be considered only "lucky" output rather than "designed" output.

John Deere like companies usually use facilities of other research institutes or universities where scholars of universities are working. They usually publish at least theoretical parts of their studies and they can be found in the literature. According to Ray from Gilmore, there is very little in the literature. and I can add that without searching any literature, I am almost sure none of their theoretical studies include the mechanism of "re-cutting the grass several times."
Also, don't belittle such engineering consultant companies like Gilmore with doctor degrees in the engineering. Institutes where Deere like big companies may have more experimental & computational facilities, but knowledge of some basical important things like "what possible - whats not possible" can be had by any person and I see Gilmore staffs too may not be different than professors at Deere institutes. Look here - I personally don't have any scientific facility now, but am able to see what Deere institute can do and what they can not do. No spin mastership here from me - spin masters are those "some"ones who tell the users "re-cutting the grass blades is being designed by major mower MFGs". Just prove us if such a re-cutting mechanism by the blade in the deck is really being designed, then I will apologize from all here. Ps: don't tell your mower is re-cutting the grass several times. They are "lucky" re-cuts due to unpredictable nature of turbulent/chaotic flows. I've seen many many scholars who have been awarded PhD degrees even though they have blown much. Turbulence field is such a field - They blow much and they think no one can disprove their blows. But they forget noise filtering technology.

Okay - this is the conclusion of topic;
Blades aren't being designed according to recycling the grass to re-cut them several times in the deck. Only averaged/mean quantities can be aimed to be obtained and this is possible simply by a simple blocking air discharge path so that the cut grass recycles into the deck and "luckily" re-cut again before it's discharged out. The mower blade design has nothing to do with these. OK?

thcri · Feb 5, 2004

Was gone for a few days but this was an interesting one to read. I guess the only thing I can say is I am so happy with my Gator Blades. They do lift the grass up much better and do mulch it in finer clippings.

murph

Villengineer · Feb 5, 2004

( John Deere like companies usually use facilities of other research institutes or universities where scholars of universities are working )
Do you know any engineers from Deere or say other companies like Cat? I do and I know that very little of their work is transfered to the educational sector. Plus, just like every other major manufacturer, if an educator does summer work for them it's the property of the company and is NOT publishable. Shoot, we make you sign a confidentiality agreement just to take a simple print out of our facility.
By the way, you're right there is nothing secret about formulas, but how they applied them maybe something you aren't aware of. That is afterall how many breakthroughs occur. Additionally, it's entirely possible that they discovered the changes in the test lab. That's where it matters anyway, who cares what the numbers say. More than once I've seen things work that the numbers said wouldn't. Just because it may not have been design using formulas doesn't make it inferior.
( Also, don't belittle such engineering consultant companies like Gilmore with doctor degrees in the engineering )
When did I belittle them? All I said was that often consultants have to pick up a specific application that they know very little about. The usually have a pretty steep learning curve to get to the same understanding of an application compared to someone who has been working with it all the time. That's not a slam, that's just reality.
( As I often said, this requires a very complicated study that can't be done by the science today - and, knowing that this can't be done now is not a secret )
Are you omnipotent? How can you, in Turkey, possiblely know for certain the capabilities of manufacturers on the otherside of the earth? Do you have a direct line to every VP of engineering in the implement manufacturing field to keep you abreast of every new idea or breakthrough? Just because you can't do it doesn't mean someone else can't.
( Just prove us if such a re-cutting mechanism by the blade in the deck is really being designed, then I will apologize from all here. Ps: don't tell your mower is re-cutting the grass several times. They are "lucky" re-cuts due to unpredictable nature of turbulent/chaotic flows )
Why not use the actual practical example of my little 20" mulching push mower? I've had it for several years and it does a tremendous job of doing just what you claim it can't be designed to do. I also know that if you try and replace the mulching blade with just a plain old generic one that it doesn't mulch very well at all. What better evidence is there? If was done 10 years ago on a $200 store brand mower then I'm sure the technology has trickled down to the $2000 mowers by now.
( I've seen many many scholars who have been awarded PhD degrees even though they have blown much. Turbulence field is such a field - They blow much and they think no one can disprove their blows. )
How true. You, if you actually have the degrees you claim, are quite possibly the best example I can think of.

smilingreen · Feb 5, 2004

Nomad, you need to fill out your profile. Seems like your hiding behind the "TR" statement. What do you do for a living? Do you work on and around mowing or farm equipment everyday like some of us do? Where are you located? Tell us something about your self. I kinda hear a lot of "Blow" going on.

nomad · Feb 5, 2004

You speak as if the science & technology at private company labs like Deere's are so better than universities & research centers. No, they are places where findings of universities&institutes are being applied. What does this mean? This mean theoretical and numerical formulations are done at the institutes & universities and they are transferred to those private company research facilities. So, knowing the basic principles, I don't need to go to Deere lab to understand what different things they are doing at their labs. Only a few labs can be ahead of universities & institutes and they are like NASA, lab city in cold Siberia, etc and all those too can be considered in the category of university & institute. Being ahead of universities & institutes in applications doesn't tell me much as they use theoretical formulations developed at science faculties/institutes like mathematics, physics and also engineering. Those private company labs can be ahead only at some special "trial-error" applications.

Other than those trial-error applications,
WHAT do them private labs do when developing a new thing? (Lets take Deere mower lab.)

They use some computational fluid & solid dynamic methods whose main inputs are theoretical formulations derived at mathematic&physic faculties & institutes.

They use some modern experimental techniques whose principals too are again based on some theoretical formulations derived at mathematics & physics faculties and institues.

What else do they do when developing a new item?
Are they setting up new classical mechanic generalized formulations? Only and only if they can do this, I will admit I don't understand their science & tech. at their private labs as they are ahead of me. If they are able to set up new classical physics/mechanic formulations, then they probably have many many mathematicans & physicans or Kolmogorov-like special ultra silent scientists they have there. If not, if they don't have many or special ones there, then their places/labs aren't much different than places like Gilmore. JD's labs can differ from Gilmore only in number of employee (researcher) with more or less same science level (PhD.) If Gilmore has 2 doctors, JD has 20, that's all the difference. (no difference in science level, only more work than Gilmore.)

You highlight "in Turkey" in your these words;
( How can you, in Turkey, possiblely know for certain the capabilities of manufacturers on the otherside of the earth? )

To be able to seem to be right in front of some people with some prejudies about the countries won't help you as I'm an individual and only individuals can be considered "knowledgable". - Anyway, how can I know? I know from their outputs, i.e. products. Their outputs/products which can also be seen in Turkey are telling me that they aren't ahead of theoretical formulations which are being transferred/transformed, say, into their mower labs for some computational and experimental works to design a new mower blade. Those mulching blades are there after the flat blades just because of using those theoretical formulations more after computers have become faster.

To understand who is blowing (me or those "some"), lets back to finish mower blade and shall I tell how it's almost impossible to re-cut the grass blade several times without using any "luck" of unpredictable flow motions around the blade?

Molerj · Feb 5, 2004

Too much Blade Sharpening in this thread for me. Good luck, I'm outta here. /forums/images/graemlins/smirk.gif

Villengineer · Feb 5, 2004

( You speak as if the science & technology at private company labs like Deere's are so better than universities & research centers )
In their given area of expertiece, yes I would say they are, in fact, ahead of universities and other un-related research centers. Eng/Sci research centers work on that which they are receiving $ to work on, and the majority of the money comes from the government. Therefore they mostly research what the government wants them to research. Industry contracts are often a second thought when they, often accidently, come across a practical application. How do I know this? I worked for a carbon fiber research facility for about a year while I was getting my BSME. All of our industry contracts were a result of us stumbling on an application and then taking it to them. Oh yeah, everyone of them made us keep their particular application confidential.
( Only a few labs can be ahead of universities & institutes and they are like NASA, lab city in cold Siberia, etc and all those too can be considered in the category of university & institute )
You are so wrong. There are lots of labs and even companies ahead of NASA and universities in many areas. How could they possibly be ahead of everyone in every area? This isn't even logical.
( Other than those trial-error applications,
WHAT do them private labs do when developing a new thing? )
What's the difference between practical trial and error and computational trial error? All the theoretical formulas were concieved using trial and error. I don't know of a single formula that someone just had an epiphany and wrote down the mathmatical representation correctly the first time.
I thought you worked in industry. I shouldn't have to tell you what thousands of engineers do everyday.
( If not, if they don't have many or special ones there, then their places/labs aren't much different than places like Gilmore. JD's labs can differ from Gilmore only in number of employee (researcher) with more or less same science level (PhD.) If Gilmore has 2 doctors, JD has 20, that's all the difference. (no difference in science level, only more work than Gilmore.) )
Again, you are out of touch with reality. Experience and ingenuity are as valuable, if not more, than abreviations after your name. For instance, where I work the least useful engineer in our department has the most advanced degrees. He couldn't design his way out of a wet paper bag. You can't always measure an individual's contribution by the degrees they hold.
( They use some modern experimental techniques whose principals too are again based on some theoretical formulations derived at mathematics & physics faculties and institues )
Once again, there can be advancement due to new applications of these formulas. Also, whether you believe it or not, I have seen formulas alterted by corporate engineering staffs to better analyze their work.
( To be able to seem to be right in front of some people with some prejudies about the countries won't help you )
I wasn't making any social statement at all, simply a geographical one. You are the one making the prejudicial statements. I was simply pointing out that you are making judgments about people with whom you have no personal contact. See, I know actual engineers, a lot of them friends, who work for various industries, labs, and even universities. I've been in them and I design equipment everyday. I get first hand information, I was questioning how you get your information when you are so far away.
( computers have become faster )
You do realize that most corporations have better computers than universities and I would even guess better than a lot of the government labs. For that matter my home computer is probably more powerful than the best computer available 10 years ago.
You have a very high opinion of yourself to think that you know more about a given subject than those who work in it everyday.

RayHope · Feb 5, 2004

Hi All.

Interesting discussion your having. After reading some of the comments after my last post, I thought I would add a few things.

The latest study we did on noise generation was done with the aid of the CFD package called Fluent (http://www.fluent.com/).

The mesh size around the blade was very fine because we were lookin at noise generation off the blade surface.

Just looking at the final blade shape we recommended does not give the full picture of the research. We learnt a lot from looking at the flow around all the shapes we tested.

All that said, the customer probably only cares about the performance. Not how it was achieved.

Regards
Ray