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Posted By: 1234567 Sharpness - 11/09/12
Does anyone know how sharp you can actually get a knife edge? I am asking about steel knives.

Also, does anyone have any idea on which steel will get the sharpest.

The reason I ask is because I have read that steel has grains in it, and the finer the grain, the sharper you can hone it, but that you cannot sharpen a grain. It would seem logical, to me at least, that the finer/smaller the grain, the sharper the blade is capable of getting.

Also, I have read that about 2 or 3 microns width is about as sharp as an edge will get.

Anyone have any input on this?
Posted By: mtnman1 Re: Sharpness - 11/09/12
here we go again...

Just go to this website...

http://www.catra.org/pages/products/kniveslevel1/slt.htm
Posted By: 1234567 Re: Sharpness - 11/09/12
That is not what the question was about.
Posted By: mtnman1 Re: Sharpness - 11/09/12
Then I have no idea what the question is about. You asked how sharp a knife can get. I gave you the machine and the index that is used to measure it as the industry standard for 50 years. You might want to first define "Sharp"... thin doesn't necessarily mean "sharp"

Have a nice day.

Posted By: 2muchgun Re: Sharpness - 11/09/12
If MM1s answer was no good, then I don't get the question either.

IME you can get just about any knife (made of decent steel) wickedly sharp. It is just that some obtain an edge easier, and some hold it longer. Other than that, wicked sharp is wicked sharp. Hard to tell which is sharper of 2 knives that will both shave hair, and at that point it really doesn't much matter, IMO.

I would say carbon steel gets sharper than stainless, in general. But that is just my opinion with no scientific research to back it up.

I would also say cold forged knives can be made very finely grained, and are capable of superior sharpness.....
Posted By: cranky72 Re: Sharpness - 11/09/12
a knife can get as sharp as you can make it. 123456 have you ever seen the videos with guys whittling a single hair? 123456 how many angels can dance on the head of a pin? we did all this a few months back. cranky72
Posted By: gotthecustombug Re: Sharpness - 11/09/12
I am just getting into the knife thing, as far as compostion goes. I sharpen a lot of knives though. I think one of my sharpest is a 1095 CS custom, made by bradshaw. That thing is sharp! It is a convex grind.

I have also sharpened a few stainless that realy took a keen edge. Some of the factory ones that have take a really good edge are japanese made spydercos, and some of the benchmade knives. Knives of Alaska made from D2 are usually a treat to sharpen too...end up scary sharp. There are others too, I just don't remember them all.

I sharpen almost all of them on my Edge Pro, professional, except the convex. There have been a few that I have converted to convex using my buffer...no brands mentionable, just depends on how they are.

Larry
Posted By: 1234567 Re: Sharpness - 11/10/12
Okay, I'll try again. I put the part about microns in because I thought that would more clearly explain what I am asking.

I want to know, if anyone knows, or how to find out, how many microns thick the edge would be where the angles converge to form the cutting edge. It doesn't have to be microns--it can be thousands or any measurement.

There is something about either grains or carbides and they would be lined up along the edge. I have read that these grains, or if they are carbides, will not sharpen. Supposedly, they will pull out of the matrix instead of abrading.

I am thinking that the sharpest edge would be a type of steel that has the finest carbides, or grains, whatever they are.

I have read that some type of volcanic rock, obsidian, I think, is the sharpest of any known object, but I am wanting to know about steel.

Yes, I did ask a similar question a few months ago, although I don't remember asking about Angels or pins, but no one gave a satisfactory answer.

As far as edge holding ability goes, I already know which steel that would be, and that is one of the things a Catra measures. I also know about splitting hairs. It would have to be very sharp.

What would be the thickness of the apex of the triangle where two of the sides converge on a knife blade so that it would split a hair?

Posted By: cranky72 Re: Sharpness - 11/10/12
i'm not sure that we have an engineer that specializes in this type measurement on this forum. the sharpest apex can be measured; remember that we now have machines that can weigh a pencil mark.123456 i believe there is certainly an answer to your question but you will probably need to consult the editors of Scientific American or MIT university, another source is Cal Polytech. now my question is how this info can possibly aid your understanding of knife performance? if it's strictly academic get your self to the engineering xperts. i ca'nt possibly see how this will aid in making knives or even using them. did you count the angels yet?--cranky72
Posted By: cranky72 Re: Sharpness - 11/10/12
Posted By: gotthecustombug Re: Sharpness - 11/10/12
I went looking...one fellow posted that a scalpel would measure about .001 mm across, and a razor blade would measure half that, approximately. I have a microscope I can hook up to the computer, that can measure that, maybe...if I get time, I may just mess with it a little.

Larry
Posted By: JSTUART Re: Sharpness - 11/10/12
Originally Posted by 1234567


Anyone have any input on this?


Yes, if you go to the campfire or hunting rifle threads and post that the .270 is better than the 30-06 you will get a longer thread, more arguments and better nudie pictures.
Posted By: 1234567 Re: Sharpness - 11/10/12
Cranky:

The reason I want to know is mainly because of curiosity. Usually, even when you will not put the information to use, I feel it is better to know than to not know.

That being said, the knowledge would, or could apply to surgical instruments, especially eye surgery, brain surgery, or open heat surgery, where a fine, clean cut, with no tearing, and very little pressure is required. Not that I am going to be doing any surgery.

It could also have applications in the field and also in slaughter houses where less effort would be necessary for a clean cut, without having to use too much pressure that the blade might slip and cut into a gut, or into your hand.

Another question is if there is a steel that, because of the chemical makeup, would be tough enough to hold the very sharp edge. I suppose there are steels, because of their micro and grannular structure, that can be made sharper than others.

I read where 440C was one steel that would qualify, because of the refinements made to the steel when used as surgical instruments, but I have no information to back it up.

If you could combine extreme sharpness with a steel with good toughness and abrasive resistance, I think you could make a superior blade. There might be steels available that would qualify. I just don't know what they would be.

With a surgical knife, edge holding would not be a large concern, because the blade could be replaced as soon as it got dull.

This is a serious question, at least serious to me. Not that I will ever use the information, but I would like to know, and I see no reason that technical information about how knives are made, and the materials, would be out of place on this forum.

Have you ever heard of a book titled 'Tool Steels', by three authors named Roberts, Hamaker, and Johnson?


To Larry:

Thanks for taking the time to research this. I hope you will find the time to make the measurements. I have tried with a 10X glass, but could not see it well enough to tell anything about it.
Posted By: usull Re: Sharpness - 11/10/12
I used to touch-up Photo-masks ( by hand ) which had circuit lines which were 0.003 to 0.004 Inches wide . As I recall , that is about the width of a female human hair . Don't know much about Custom Knives , but you might be able to make some estimates of what the knife edge should be to split such a Hair . BTW , I have not been at all impressed with the few Customs I have purchased so far . They are beautiful , but NONE have been anywhere near Sharp enough to shave hand hair . With that said , I do not want to attempt Sharpening these as that would affect resale especially since I don't have a lot of experience sharpening . I'm looking for Recommendations on a Factory Knife that would fit my large hand ( maybe a drop point design , maybe not ) and be close to shaving hand hair sharp . Also as to where to buy it . TIA .
Posted By: 1234567 Re: Sharpness - 11/10/12
I don't own any, but I know a person who collects those cheap knives made in China.

The ones I have handled are shaving sharp, seemingly much sharper than many of the American made knives. For a 4 or 5 dollar knife, they appear to be very well made. I don't understand how they can make a knife of that quality so cheap.

As far as how long the blade would stay sharp, I don't know. I don't know anything about the steel or the heat treatment.

As far as the sharpness of custom knives, there has been a lot written on this forum about sharpening and edge geometry and sharpness, and how much they can be used and still stay sharp.

I have made several hundred knives, and my experience, with the steel and heat treatment I use, just does not coincide with much of what I have read here.
Posted By: cranky72 Re: Sharpness - 11/10/12
123456 you can rest assured that tn\he questions you asked have already been answered by manufacturing facilities the world round. you are wasting your time asking these questions on this forum. there have been thousands of books written on tool steels get up to modern times & research these---m390,elmax, 3v , 4v, k294. watch the videos of the chopping contests. your revelations wo'nt surprise any metallurgists of the last 20 or 30 years. i answered your question earlier.cranky72
Posted By: 1234567 Re: Sharpness - 11/11/12
"you are wasting your time asking these questions on this forum."

If nothing else, I would have to agree with you on this. You did not answer the question. I don't think you even understand the question, and if you do, you have a funny way of answering it.

Someone said you were the expert on blade steel. I think that someone went off and neglected to tell you the truth.

Incidentally, I asked the original question because I wanted to know. I did not ask the question to listen to some of your know-nothing crap. I asked here because I thought someone with metallurgical experience might know.

Believe it or not, there are people in this world, and on this forum, who know things that you don't, and if these people do not know, they do not try to cover up their lack of knowledge by ridicule.

If you don't know the answer, why don't you admit it and say so, instead of trying to make yourself look smart and important by putting someone else down?
Posted By: cranky72 Re: Sharpness - 11/11/12
well 123456 i can see you still have'nt counted the angels on the pinhead. your basis of knowledge has stagnated since the 60s. you are dumber than a brick but too unitelligent to realize it. my sweet potatoes have more sense than you.--cranky72
Posted By: Journeyman Re: Sharpness - 11/11/12
Originally Posted by 1234567
Does anyone know how sharp you can actually get a knife edge? I am asking about steel knives.

Also, does anyone have any idea on which steel will get the sharpest.

The reason I ask is because I have read that steel has grains in it, and the finer the grain, the sharper you can hone it, but that you cannot sharpen a grain. It would seem logical, to me at least, that the finer/smaller the grain, the sharper the blade is capable of getting.

Also, I have read that about 2 or 3 microns width is about as sharp as an edge will get.

Anyone have any input on this?


I, for one, enjoy your enthusiasm for the topic. But, with all due respect, you do seem to tend toward preconceiving the answer you wish to hear based on some limited amount of informal research. As has been said above, none of this is new.

With your keen interest you'd be well served to do more formal study, because frankly, not that many folks on a general message board are going to be that deep into the subject.

I'd suggest you get a copy of this book for starters: The Science and Engineering of Cutting

Pay particular attention to the sections on cutting edge geometry; and here's a clue: Your focus on edge thickness is off base. The grind and the angle of the edge bevel is more linearly related to your notion of "sharpness" than the edge thickness...
Posted By: cranky72 Re: Sharpness - 11/11/12
thanks journeyman for a courteous & intelligent input. i guess i've gotten too old to have much patience with idiots. cranky72
Posted By: 1234567 Re: Sharpness - 11/11/12
"With your keen interest you'd be well served to do more formal study, because frankly, not that many folks on a general message board are going to be that deep into the subject."

This forum was a place to start. I thought that there might be a few engineers who are familiar with the subject and could answer my question.

Steel catalogs and web sites probably do research on what I am trying to find out, but I have never read anything in one of their catalogs about it, except for the remark I made about 440C and how it has been refined to make very sharp surgical instruments.

Look, I did not ask this question to get into a mud fight with Cranky, but it seems to be unavoidable, given his temperament. As far as being an idiot, any time he wants to compare IQs, I can do that.

Maybe we can let Mensa determine who would be the winner. I will submit my membership number, if he will submit his, if he has one.
Posted By: antlers Re: Sharpness - 11/11/12
Originally Posted by 1234567
Maybe we can let Mensa determine who would be the winner. I will submit my membership number, if he will submit his, if he has one.

Don't bother. The fact that you guys are bickering over the schit that you are, on a forum for knife enthusiasts, would automatically disqualify either of you. No offense.
Posted By: cranky72 Re: Sharpness - 11/11/12
my 145 does'nt qualify for mensa but i can extrapolate 123456 to be about 95. i already told that idiot to call engineering at cal poly tech. he probably thinks i'm talking about dog food.--cranky72
Posted By: 1234567 Re: Sharpness - 11/12/12
Originally Posted by antlers
Originally Posted by 1234567
Maybe we can let Mensa determine who would be the winner. I will submit my membership number, if he will submit his, if he has one.

Don't bother. The fact that you guys are bickering over the schit that you are, on a forum for knife enthusiasts, would automatically disqualify either of you. No offense.


I agree. No offense taken.

If anyone is interested in knowing, I did find what I was originally asking about. It is one molecule, with a possibility of going on down to one atom thickness.
Posted By: pike3e Re: Sharpness - 11/13/12
There is no such thing as molecules in steel. Steel is a crystaline structure of iron atoms with differing amounts of alloying elements.

As journeyman stated, there are many other factors involved with making a sharp knife. I shave with a straight razor, it it is extremely sharp (12000 grit stone and stropped) and it cuts whiskers great. However it is almost completely useless in cutting other things because the edge is so thin it would be damaged. something a few atoms thick would be completely useless as a knife.
Posted By: 1234567 Re: Sharpness - 11/13/12
When they were talking about one atom or one molecule thickness, I think they were talking about obsidian and broken glass. They were fine enough to cut between 2 cells, during surgery.

Yes, the edges would be thin and damage easily. The usefulness would come in for eye and other types of surgery where a cut, and not a tear, was necessary, to lesson bleeding and promote quick healing.

There was also mention of a titanium alloy, that could be given a very fine, but fragile edge, but there was no discussion about it.

I found the subject interesting, although no one else seems to. My primary interest was concerning steel, something a knifemaker would have some control over, if he was looking for a steel that would give the very sharpest blade.

About molecules--molecules are the smallest particles a substance can be broken down to, and still retain the original substance. Molecules only occur with two or more elements combine, as opposed to mixing.

With steel containing several elements, 5 or 6 at least, isn't it possible that two or more of these elements would or could combine, forming molecules?
Posted By: ryanjay11 Re: Sharpness - 11/13/12
Science isn't your strong suit.
Posted By: RaySendero Re: Sharpness - 11/13/12
1-7,

I collect knives. I also, know something about technical questions and answers. But in this case, I don't know the answer the way you want it.

I can offer the answer my grandfather had:

Hold the knife with blade up under a light so that it will reflect off the knife's edge. Look for this reflection - That's where the blade is dull. Sharpen the edge untill all reflection goes away. Try to slide the edge down across your thumb nail at about a 45 degree angle. When the edge is sharp enough, It will catch on your finger nail and stop sliding. Check all the points along the edge this way that you found dull and thus had sharpened.

Good luck finding the other answer you wanted.
Posted By: 1234567 Re: Sharpness - 11/13/12
I want the answer in inches. The width, in inches where the two sides come together to form the cutting edge.

I have found some of the answer. Some razor blades measure .4 Microns at the apex where the two bevels come together. Now, I am trying to find out the size of 1 Micron in inches.

I understand what you are talking about. I have used the same methods to test for sharpness.

I am asking the technical questions because I am curious to know this measurement. For example how sharp is sharp?

I have read that obsidian is 100 times sharper that it is possible to get the sharpest steel blade. Makes me wonder how thick the obsidian is at it's cutting edge.



Posted By: 1234567 Re: Sharpness - 11/13/12
"There is no such thing as molecules in steel. Steel is a crystaline structure of iron atoms with differing amounts of alloying elements."

Carbon will combine with many elements that go into the making of steel. So will the element iron. Cobalt is used in some high speed steels. Cobalt will combine with iron, nickel, and sulfur, of which all are elements that comprise different types of steel.

Nitrogen will combine with iron. Oxygen will combine with the elements in steel, causing Iron Oxide, aka rust. Rust has molecules.

So yes, steel is a compound and contains molecules.
Posted By: pike3e Re: Sharpness - 11/15/12
WOW, posts like this are why I dont argue on the internet, carry on.




Originally Posted by 1234567
"There is no such thing as molecules in steel. Steel is a crystaline structure of iron atoms with differing amounts of alloying elements."

Carbon will combine with many elements that go into the making of steel. So will the element iron. Cobalt is used in some high speed steels. Cobalt will combine with iron, nickel, and sulfur, of which all are elements that comprise different types of steel.

Nitrogen will combine with iron. Oxygen will combine with the elements in steel, causing Iron Oxide, aka rust. Rust has molecules.

So yes, steel is a compound and contains molecules.
Posted By: Seminole39 Re: Sharpness - 11/15/12
as long as it will cut baling twine, i don't care
Posted By: 1234567 Re: Sharpness - 11/15/12
Originally Posted by pike3e
WOW, posts like this are why I dont argue on the internet, carry on.




Originally Posted by 1234567
"There is no such thing as molecules in steel. Steel is a crystaline structure of iron atoms with differing amounts of alloying elements."

Carbon will combine with many elements that go into the making of steel. So will the element iron. Cobalt is used in some high speed steels. Cobalt will combine with iron, nickel, and sulfur, of which all are elements that comprise different types of steel.

Nitrogen will combine with iron. Oxygen will combine with the elements in steel, causing Iron Oxide, aka rust. Rust has molecules.

So yes, steel is a compound and contains molecules.


Asking simple questions like this one, and the responses I got from some people just about broke me from asking questions on the internet.

I wanted to ask you some questions about Damascus, but I think that would be a waste of time, and would lead to more insults.
Posted By: cranky72 Re: Sharpness - 11/16/12
obsidian is'nt the sharpest edge--the diamond knife is. diamond knives are used to cut extremely thin tissue samples since even smaller lasers burn the real thin sections that are needed for microscopic study. obsidian was given up in favor for eye surgery since lasers could cut better & thinner. as mentioned science is'nt your strong shirt. please 123456 discuss something you understand so other members may be able to contribute. we are'nt impressed with your shallow science knowledge.---cranky72
Posted By: 1234567 Re: Sharpness - 11/16/12
Have you ever considered therapy?

I understand, and also understood completely. I asked a simple question and it took 4 pagers not to answer it. All I wanted was a simple measurement, if anyone knew what it was.

The question was like asking something like how thick is a 2X4 and you fill 4 pages with what you don't know.

My knowledge might be shallow, but you will never see me putting someone down, as you seem to excel at, to cover up for a lack of knowledge and to try to cover up for an excess of stupidity.

Only the backwards and the inbred do as you are doing. Stop trying to be something you are not, like knowledgeable about steel and knife making, and telling people where to find the answers to questions you do not understand.

Who is this 'we'? Do you have a mouse in your pocket?
Posted By: doubletap Re: Sharpness - 11/16/12
Originally Posted by 1234567
how thick is a 2X4

1��
Posted By: pike3e Re: Sharpness - 11/16/12
I did not insult you and will not. I would be more than willing to answer questions about damascus, to the best of my knowledge. However I will not go round and round pointlessly.


Originally Posted by 1234567
Originally Posted by pike3e
WOW, posts like this are why I dont argue on the internet, carry on.




Originally Posted by 1234567
"There is no such thing as molecules in steel. Steel is a crystaline structure of iron atoms with differing amounts of alloying elements."

Carbon will combine with many elements that go into the making of steel. So will the element iron. Cobalt is used in some high speed steels. Cobalt will combine with iron, nickel, and sulfur, of which all are elements that comprise different types of steel.

Nitrogen will combine with iron. Oxygen will combine with the elements in steel, causing Iron Oxide, aka rust. Rust has molecules.

So yes, steel is a compound and contains molecules.


Asking simple questions like this one, and the responses I got from some people just about broke me from asking questions on the internet.

I wanted to ask you some questions about Damascus, but I think that would be a waste of time, and would lead to more insults.
Posted By: mtnman1 Re: Sharpness - 11/16/12
Originally Posted by 1234567
you will never see me putting someone down


Originally Posted by 1234567
Only the backwards and the inbred do as you are doing.



Your inference seems to be contradictory!
Posted By: cranky72 Re: Sharpness - 11/17/12
123456 made knives light years away But does'nt understand his 1960 knowledge is caveman expertise at present. a while back he even said nitrogen guenched blades would shatter like glass if dropped. its obvious he does'nt understand newer alloys & heattrears, even buck is using nitrogen in many production models. i think its time he went back to school.--cranky72
Posted By: 1234567 Re: Sharpness - 11/17/12
Crackey:

If you are going to say crap like this, at least tell the truth. I don't know where you got your information, but I never said a nitrogen quenched blade would shatter like glass. I know better than that. You should, too, being the expert you are.

As far as heat treating, and this is factual, and not an argument, although I am sure you will turn it around to mean just the opposite. Actually, I am not sure you will turn it around. You seem to have a knack of getting things backward regardless of how simple they are put.

But as for heat treating. Many years ago, I wanted to heat treat my own knives and I researched heat treating. I discovered that for high chrome, high carbon steels, such as 440C, ATS 34, 154CM, D2, and others, that if they were not protected by a neutral atmosphere, they would decarbonize.

For that reason, and the equipment needed to do it right, I decided to use a commercial heat treater. I felt home heat treating was beyond my abilities, and for these steels listed they could not be correctly heat treated by back yard methods. I still think that.

My choice was Paul Bos. If you consider him to be a caveman, then nothing I can say will ever make any sense to you.

I felt then, and I still do, that an incorrectly heat treated blade is worthless. The best and most expensive steel in the world will not make a suitable knife if the heat treating is done incorrectly.

I hope this clarifies things, but I have my doubts, knowing a little about your reasoning, or lack thereof, and your lack of plain common sense.

Those are the actual facts. If you try to make something else out of it, then you are a liar. But then, you know that, don't you?
Posted By: 1234567 Re: Sharpness - 11/17/12
Originally Posted by doubletap
Originally Posted by 1234567
how thick is a 2X4

1��


Before it is planed?
Posted By: cranky72 Re: Sharpness - 11/17/12
i only hope 1234 has learned something from all the contributors that tried to explain some facts to himself.--cranky72
Posted By: RaySendero Re: Sharpness - 11/26/12
Originally Posted by 1234567
I want the answer in inches. The width, in inches where the two sides come together to form the cutting edge.

I have found some of the answer. Some razor blades measure .4 Microns at the apex where the two bevels come together. Now, I am trying to find out the size of 1 Micron in inches.

I understand what you are talking about. I have used the same methods to test for sharpness.

I am asking the technical questions because I am curious to know this measurement. For example how sharp is sharp?

I have read that obsidian is 100 times sharper that it is possible to get the sharpest steel blade. Makes me wonder how thick the obsidian is at it's cutting edge.





1-7,

I find it hard to believe that you can read/find/understand "the obsidian" which, has been tried as surgical scalpel blades and yet not find the conversion from microns to inches! LOL
Posted By: 1234567 Re: Sharpness - 11/26/12
I found it since I made that post.

1 Microns = 0.00003937007874015748 Inches
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