Blade Geometry.

[Ankerson]

Like I said in my other post, it's very basic stuff here, it's not complicated at all.

WRONG! I need graphs and pie charts and statistics and analogies and comparisons! I need blind tests conducted by cutting thousands of feet of randomly selected cardboard, I need blindfolds and unmarked blades ground exactly the same by a machine! I can't wrap my mind around all this simplicity and common sense!

Well yeah. :D

One could explain it that way writing a book and spending all that time writing, oh I mean copying and pasting walls of text and those charts from some other place, you know the same stuff over and over and over. Therefore confusing everyone to the point they couldn't possibly understand or even finish reading it or want to for that matter. LOL

Or

Show a few photos like I did and let common sense take over. ROFL :D

[edge-e]

Yes, blade geometry is common sense to those that understand the geometry to begin with. If one doesn't know what .010" is over .040" there will be a problem. There is stock thickness, behind the edge measurement as well as blade height to be considered. Two blades, both are .100" thickness and .008" behind the edge. One blade is 1" tall the other is 2" . The 2" blade will cut better and maintain a thinner section longer. The other 1" tall blade will have more durability as it thickens quicker with the shorter height.
Jim, that phil wilson knife looks like a good cutter. That slicer along with a pack axe for heavier work who needs that other one!

[jackknifeh]

IMO here is the thing with cutting performance. The thinner the blade is and the lower the angle of the edge bevels the better the knife will cut. This is true no matter what. The issue that occurs of course is that knives also need to be strong enough to handle any twisting or side pressure that gets put on knife blades. So the EDC pocket knife blade needs to be thicker than a straight razor (for example). The three blade grinds I've experienced are full flat grind (FFG), saber grind and hollow grind. I don't particularly care for the saber grind Delica (for example) because the blade gets thicker too fast. This degrades cutting performance for me a lot of the time. Cutting cardboard for example. But for any kind of paper, string, or many common tasks the saber grind is fine. Anytime you are cutting something that isn't very thick. Then you have the FFG. This is my favorite for EDC I think. A FFG blade with low edge angle provides about as good cutting performance as you will get. OTOH, the hollow grind on my GB glides through cardboard. When cutting cardboard that is thin the GB is as good as a FFG blade in my experience. But if the cardboard is thick the resistance created when the upper part of the blade tries to seperate the cardboard the cutting gets more resistance. You can argue that when the spine of a FFG and a hollow grind is the same thickness the performance will be the same or very close. But if you are cutting cardboard as it lays on a piece of wood the GB will glide through it because the hollow grind is thinner behind the edge than a lot of FFG blades. One thing I try to do when cutting thicker cardboard is to keep the blade at a 45 degree angle with the cardboard. I mean the angle is determined by the lines along the cardboard and along the length of the blade. By holding the angle like this the cardboard is easily seperated compared to when the blade is at a 90 degree angle with the cardboard. So if you are using a knife with a real thick blade you can improve the performance by how you hold it (sometimes).

Personally, I don't care for saber grind. FFG and hollow to me don't have enough difference in cutting performance to make a huge difference. Both are great. When talking about EDC knives we may be cutting any number of different things. Therefore FFG vs hollow are the same for my choice. But in situations where the cutting is very specific one grind may be an obvious better choice.

Jack

[Ankerson]

Yes, blade geometry is common sense to those that understand the geometry to begin with. If one doesn't know what .010" is over .040" there will be a problem. There is stock thickness, behind the edge measurement as well as blade height to be considered. Two blades, both are .100" thickness and .008" behind the edge. One blade is 1" tall the other is 2" . The 2" blade will cut better and maintain a thinner section longer. The other 1" tall blade will have more durability as it thickens quicker with the shorter height.
Jim, that phil wilson knife looks like a good cutter. That slicer along with a pack axe for heavier work who needs that other one!

Yeah most of it people should understand, decimals are middle school level math (6-8th grade) and Geometry is High School math, usually 9th Grade. Figure most people made it through High School so it shouldn't be all that difficult to explain a pretty basic concept and keep it simple.

Yes it's a great cutter for sure, saw or an axe would be all that would be needed. :)

[Ankerson]

IMO here is the thing with cutting performance. The thinner the blade is and the lower the angle of the edge bevels the better the knife will cut. This is true no matter what. The issue that occurs of course is that knives also need to be strong enough to handle any twisting or side pressure that gets put on knife blades. So the EDC pocket knife blade needs to be thicker than a straight razor (for example). The three blade grinds I've experienced are full flat grind (FFG), saber grind and hollow grind. I don't particularly care for the saber grind Delica (for example) because the blade gets thicker too fast. This degrades cutting performance for me a lot of the time. Cutting cardboard for example. But for any kind of paper, string, or many common tasks the saber grind is fine. Anytime you are cutting something that isn't very thick. Then you have the FFG. This is my favorite for EDC I think. A FFG blade with low edge angle provides about as good cutting performance as you will get. OTOH, the hollow grind on my GB glides through cardboard. When cutting cardboard that is thin the GB is as good as a FFG blade in my experience. But if the cardboard is thick the resistance created when the upper part of the blade tries to seperate the cardboard the cutting gets more resistance. You can argue that when the spine of a FFG and a hollow grind is the same thickness the performance will be the same or very close. But if you are cutting cardboard as it lays on a piece of wood the GB will glide through it because the hollow grind is thinner behind the edge than a lot of FFG blades. One thing I try to do when cutting thicker cardboard is to keep the blade at a 45 degree angle with the cardboard. I mean the angle is determined by the lines along the cardboard and along the length of the blade. By holding the angle like this the cardboard is easily seperated compared to when the blade is at a 90 degree angle with the cardboard. So if you are using a knife with a real thick blade you can improve the performance by how you hold it (sometimes).

Personally, I don't care for saber grind. FFG and hollow to me don't have enough difference in cutting performance to make a huge difference. Both are great. When talking about EDC knives we may be cutting any number of different things. Therefore FFG vs hollow are the same for my choice. But in situations where the cutting is very specific one grind may be an obvious better choice.

Jack

That was the balance I was talking about. :)

[Cliff Stamp]

IMO here is the thing with cutting performance. The thinner the blade is and the lower the angle of the edge bevels the better the knife will cut. This is true no matter what.

No it isn't, I noted why in the above.

... because the hollow grind is thinner behind the edge than a lot of FFG blades

This has nothing to do with the fact it is a hollow grind, only how it was hollow grind. TOP's for example are hollow ground but optimized for heavy durability and have very thick cross sections.

[JD Spydo]

For me it comes down to a few things:

If someone is interested enough to explore the other end of the spectrum then you take the time to teach, but often you'll end up in the same debate as trying to make someone understand why their $10 flea market knife is inferior to your Spyderco.

When money comes into the conversation things usually go sideways in a real hurry so things are typically less about the knife and more about the money.

There is a lot of garbage out there, much more garbage than quality and it does sell, if it's cheap it will sell is the bottom line there.

So in the end even trying to argue with a lot of them is pointless most of the time if they aren't even in the Buck 110 price range or Spyderco Byrd range before one even starts talking to them.

The really amusing thing is when one starts to think about how much money it costs to manufacture some of these things, figure the retail is $10 to $20, that's retail.. Start figuring in manufacturing costs, overhead, materials, packing and shipping, the markups and we start getting down into the sub $3 range to actually make this garbage in the 1st place. Sometimes it can cost more money to ship the knife from the store to the buyer than it cost to manufacture the thing.

If someone actually thinks they are getting something worth buying then let them fool themselves into thinking that.

Ankerson you hit the nail so directly on the center of the head :cool: Like yourself I encounter the folks that tell me that they can get a knife just like mine or even better than mine at "SuperFlea" ( fleamarket within a mile of my house :mad: ). The two times I actually tried to start an intelligent conversation about the simple fact of "YOU GET WHAT YOU PAY FOR" and to see them actually become livid when you explain that this 3rd World **** Hole Made piece of junk that Rip-Mart won't even lower themselves to sell ( and that's pretty bad folks because Rip-Mart has little conscience and could care even less about "QUALITY" on any item they sell :mad:

I know this thread is about Blade Geometry so I'll try not to derail it>> but this aspect of the conversation needs to be covered because you could have a super ergonomic design like the C-60 Ayoob for instance but if the steel is made in North Korea ( or worse ) then your best designed blade is still nothing more than a SuperFlea rip off at best. You must start with quality materials before any factor like blade geometry or ergonomics or handle design or any other aspect of the construction of a knife is even worth considering at all. Again Ankerson I find myself on the same page>> great post my friend :)

[Cliff Stamp]

You must start with quality materials before any factor like blade geometry or ergonomics or handle design or any other aspect of the construction of a knife is even worth considering at all.

The cutting ability of a knife is determined by the geometry, it isn't influenced by the material. Ergonomics is very weakly dependent on the handle material, aside from extremes such as comfort in cold when the grip is metallic.

The vast majority of work in the work with knives is done with very inexpensive ones, and ironically they tend to cut much better than the expensive knives because of the way they are ground/sharpened.

Now it is true that you can make the argument that better materials can allow better products, but few knives really push this limit. How common for example is it to find a folding knife that cuts better than an Opinel?

[Ankerson]

For me it comes down to a few things:

If someone is interested enough to explore the other end of the spectrum then you take the time to teach, but often you'll end up in the same debate as trying to make someone understand why their $10 flea market knife is inferior to your Spyderco.

When money comes into the conversation things usually go sideways in a real hurry so things are typically less about the knife and more about the money.

There is a lot of garbage out there, much more garbage than quality and it does sell, if it's cheap it will sell is the bottom line there.

So in the end even trying to argue with a lot of them is pointless most of the time if they aren't even in the Buck 110 price range or Spyderco Byrd range before one even starts talking to them.

The really amusing thing is when one starts to think about how much money it costs to manufacture some of these things, figure the retail is $10 to $20, that's retail.. Start figuring in manufacturing costs, overhead, materials, packing and shipping, the markups and we start getting down into the sub $3 range to actually make this garbage in the 1st place. Sometimes it can cost more money to ship the knife from the store to the buyer than it cost to manufacture the thing.

If someone actually thinks they are getting something worth buying then let them fool themselves into thinking that.

Ankerson you hit the nail so directly on the center of the head :cool: Like yourself I encounter the folks that tell me that they can get a knife just like mine or even better than mine at "SuperFlea" ( fleamarket within a mile of my house :mad: ). The two times I actually tried to start an intelligent conversation about the simple fact of "YOU GET WHAT YOU PAY FOR" and to see them actually become livid when you explain that this 3rd World **** Hole Made piece of junk that Rip-Mart won't even lower themselves to sell ( and that's pretty bad folks because Rip-Mart has little conscience and could care even less about "QUALITY" on any item they sell :mad:

I know this thread is about Blade Geometry so I'll try not to derail it>> but this aspect of the conversation needs to be covered because you could have a super ergonomic design like the C-60 Ayoob for instance but if the steel is made in North Korea ( or worse ) then your best designed blade is still nothing more than a SuperFlea rip off at best. You must start with quality materials before any factor like blade geometry or ergonomics or handle design or any other aspect of the construction of a knife is even worth considering at all. Again Ankerson I find myself on the same page>> great post my friend :)

Yeah I see a lot of Flea Market knives around when I actually see someone carrying a knife that is, once in a great while I might see a Benchmade if I am lucky.

But hey what can you do, as long as they don't start talking some crazy stuff I usually don't say all that much.

Had some guy ask me if I got one of the my knives at Wal-Mart once, it was pretty funny really because it was an Umnumzaan.

Another guy who was a big gun collector, has a ton of guns was looking at my Strider SmF CC and really liked it, asked how much it was and I thought he was going to pass out when I told him, he turned white as a sheet.

Had my Stretch called a murder knife.

Another guy ask if I got my Military XHP at Wal-Mart.

So that's for the most part what I typically run into to around my area, stuff like that.

[jackknifeh]

IMO here is the thing with cutting performance. The thinner the blade is and the lower the angle of the edge bevels the better the knife will cut. This is true no matter what.

No it isn't, I noted why in the above.

I stand corrected. I found your post where you comments made my statement incorrect. My statement was limited to pocket knives being used for what I use pocket knives for. Once you started talking about an ax I had a good idea where you were going and I instantly knew why my opinion was limited to a small sample of cutting needs and tools. So I guess I'll have to stop using the statement I used.

... because the hollow grind is thinner behind the edge than a lot of FFG blades

This has nothing to do with the fact it is a hollow grind, only how it was hollow grind. TOP's for example are hollow ground but optimized for heavy durability and have very thick cross sections.

Again I stand corrected because the statement was regarding, usually, only pocket knives, mostly Spyderco's and also the knives I've owned.

Jack

[Ankerson]

Somehow I knew that someone would bring up the irrelevant AXE thing back up. AXES are totally and completely different than the typical knife blade, the geometry on an axe is extremely complex compared to the typical knife blade. And the typical felling axe weighs in the 3 to 5 pound range, that's pounds, not ounces.

And another topic being commercial knives, another irrelevant topic because MOST workers use what is supplied to them by the companies they work for. Yes that's right, SUPPLIED TO THEM...

Now this is my wheelhouse because I spent the better part of 25 freaking years in the Commercial/Retail Food Industry in management so I have a good idea of what goes on and what most people have to use, that's right I said HAVE TO USE.

There are very strict guidelines that have to be met, that's Servsafe here in the USA when talking about the materials a knife has to me made from to meet the SERVSAFE requirements. And people like me checked at a min of 3 times a day that those standards are met. That's not including the Heath Inspections and ServSafe Inspections that happen to make sure all of those guidelines are met. This is serious stuff here, not trivial at all, people can and have died because the guidelines weren't met and not held to the standards.

Now yes there are some people who have bought their own knives, but they have to meet the same requirements, that's Servsafe guidelines so they for the most part buy their knives from the same suppliers that the Companies do.

The knives are typically inexpensive ($9 to $25 Depending) and the companies by them in bulk and they are typically ordered by a member of Management as needed at the local locations.

When maintenance is needed they are sent off to be sharpened to a commercial sharpening service, some places have power knife sharpeners on site. Once they wear out and they don't typically last very long with the consistent use and sharpening they see they are thrown out and replaced. Basically throw away knives when we get right down to it.

Yes, they are available to anyone who wants to buy them at the Commercial supply houses and they are cheap for those who might want to use them in their own kitchen or for other uses.

So the next time someone tells you that low cost knives are used more than any other in the Commercial/Retail Industry etc you can say so, who cares.

Just a little reality for the forum as this started to go off into the fantasy areas again. :rolleyes:

[tvenuto]

Just a little reality for the forum as this started to go off into the fantasy areas again. :rolleyes:

Thanks for bringing us back, Jim, I was finding myself hypnotized by crazy incomprehensible graphs and data again.

[Ankerson]

Just a little reality for the forum as this started to go off into the fantasy areas again. :rolleyes:

Thanks for bringing us back, Jim, I was finding myself hypnotized by crazy incomprehensible graphs and data again.

It just gets out of hand once in awhile, something that I will never understand why it happens. LOL :D

I don't subject myself to the walls of text, graphs, shilling and continuous spamming for their forum and such anymore and my stress level has gone down a lot...And I am a happier person because of it. Ignore is a great forum feature IMO, it's like therapy, only wish the posts were completely blacked out so I wouldn't even see them at all. :cool:

I fail to see the relevance in throw away knives and Axes compared to our loved Spyderco, Benchmade and Chris Reeve knives we typically carry.

Last time I checked a Military or a Sebenza aren't throw away knives or axes.

But then some people tend to believe that everyone here is too stupid to tell the difference.

[Cliff Stamp]

Once you started talking about an ax I had a good idea where you were going and I instantly knew why my opinion was limited to a small sample of cutting needs and tools.

It isn't limited to axes, I used an axe because most people can clearly understand the principles involved and see the physics visually as it is on a large scale. It is easy to cut wood with an axe and see the wood has been "broken" as it were and if the axe was simply made thinner it would not cut well at all, in fact it at some point would fail to be effective. Again these are very dramatic and obvious as you can see the effects by eye.

However the same principles are involved in many other types of cutting as simple as slicing a potato or filling a fish. The optimal blade geometry has to have the necessary strength to maintain stiffness, or flexibility, and/or be thick enough to cause the material to pass the resilience and stop it from binding on the blade. In some cases, it needs thickness to create curvature to break contact and deal with surface friction as well.

Hence why for example on Japanese blades the primary grind has a very particular faceted grind and if you were to just flatten it and make it thinner it would reduce the cutting ability in many cases.

--

Now generalizations are a great place to start. The work Mike Swaim did in the 90's where he challenged the notion that steels cut and he argued that the edge angle and grit finish were most critical are very valuable. Joe and Steve expanded on that in the early 2000's by noting how critical edge thickness were as well on both cutting ability and even durability. Further how in many cases when people were talking about one knife being more durable/cutting better they were not seeing anything to do with the maker or the steel but just the edge.

However none of these people argued that is all there is and there is nothing more to learn, nor are those simple generalization themselves even a stopping point. For example how do you answer this question :

-At what angle / grit finish do you sharpen 420HC to have the same edge retention as S90V with a 15 DPS/medium rod finish slicing 1/2" hemp?

That generalization you cited doesn't allow that question to be answered, it doesn't even make it clear that question has an answer. But if you do actually look beyond the simple generalizations and look at how the angle specifically influences performance, which yes does require some data and some graphs and numbers (actual science) then you can answer that question, and some people find such things of use and interesting.

There are all kinds of such questions - for example do grantons actually improve cutting performance? If so on what kinds of foods? Is there any difference between the grantons found on Henckels vs the true/real Granton knives? If you are doing work in a kitchen on what kinds of foods do you have to cut and how, to make a knife with a thicker profile with a chip breaker type profile to work better than a full flat ground blade which can bind/stick? Is there a way to make the flat grind blade not stick by adding grantons or a hollow relief grind and thus over all have higher performance than the blade with a chip breaker grind? How much belly on an edge is optimal for a chef's knife in non-rock type chopping before it starts to be a problem? How much belly is needed to give long term edge retention on push cutting hard to cut foods like a tomato?

Again there are some people interested in these questions and there are some blades which have very complex grinds in order to actually produce such performance.

There is a lot to look at in performance of knives, some people are interested in the details some are not. But lets not pretend they don't exist simple because interests differ. I have very little interest in cars aside from being able to move me from one point to another, however this doesn't mean that I actually believe that is all they are.

[Cliff Stamp]

The things that need to be clarified here are getting to be a bit silly. In regards to axes, a common felling axe, full size, was thinner in the bit grind than a Military in fact it was (and still is) similar to the Air. Axes, like knives, in the last generation have completely lost touch with functional reality in terms of geometry. If you don't have the experience of using an axe and you want a reality check, then read the bible on axes by Cook.

A felling axe, and against this is a full size axe, has an apex angle of ~15 dps, which is reduced very fast below that. For hard / dense wood like black spruce, the bit would be ~1/4" thick at 2" back from the bevel. If this doesn't hit you right away then draw it out on a piece of paper and look at how shallow of a wedge it makes. On soft wood like clear pine the bit would be much thicker to prevent wedging.

A boys axe, the 3/4 size, would be much slimmer and a small hatchet even slimmer again because the impact forces used scale down. But they all work on the same principle as having the necessary cross section to over come the resilience of the material otherwise they don't work. The same principle also is taken into account on non-chopping axes which are used for carving/roughing which also adjust the bit curvature to a flatter edge (less belly) as they don't need the shearing action of the curvature nor the protection of the toe/heel.


This again isn't just an axe issue, it happens on any material cut with any knife because the physical equations are always the same, the only thing that changes are the material constants of the media being cut. Thus depending on the properties of the material the geometry has to be optimized accordingly. Here are three kitchen knives :



-expensive Chutoh
-inexpensive PC chef
-dirt cheap Endura (ironic, that is the brand name - Spyderco should sue !!!)
-henckels basic line

If you use these on a carrot you get one type of performance in terms of work/efficiency rating. If you use them on a potato you get a different one. That very cheap Endura which has a very thick low/sabre grind actually cuts a potato with far less force than the Henckels which has a high flat grind, thinner edge and lower edge angle.

Again these things are of interest to some people and knifemakers who use complex grinds, transition bevels, chip breakers, etc. to reduce all forces on a knife. Now some of them don't understand the physics, often times I get sent a knife or asked a question as they are curious why it works and want to understand the how/why.

If you don't, no issues. I don't really care that much for example on bread making as I make it more so I can eat fresh bread and do so in really basic ways and I know very little about bread making. I have friends who take it so seriously they can't even watch me make bread, it is like I am committing some great sin of dough manipulation.

Different people, different interests.