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Thread: thiner edge stability

  1. #1
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    thiner edge stability


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    hello all. im a fan of either thick beastly knives like 5/16ths inch thick, or either extremely thin edge grinds that require more maintainence. all knives experience performance trade offs in terms of strength and edge holding when thin, but has anyone noticed their zero or scandi grind or thin profile that seems to hold up better than other steels for a shaving edge under edc use? thanks

  2. #2
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    IF cutting materials without placing them against a hard backing, I've liked how thinner edge profiles hold up (I'm talking maybe 30° or less, inclusive). An edge with thinner geometry is a much more efficient slicer, requiring much less force exerted directly against the cutting edge. That really helps with edge durability, so long as the thinner edge doesn't get slammed into a hard substrate under the material being cut. A thickish edge (>40° inclusive) is more 'durable' in the sense that it's shape won't be altered as severely when contacting something hard. But I don't see much advantage in maintaining the geometric integrity of a thick edge that doesn't cut as well anyway, even when it's 'sharp'. A thinner edge can continue to function well for most real-world cutting tasks, even after the shaving sharpness goes away, because the underlying geometry behind the edge still works. BUT, a thick edge will be immediately blunt and unusable as a true cutter/slicer, for the most part, just as soon as the crisp apex is gone. After that, it's basically just an axe-edge for hacking at stuff. Most of my real-world EDC uses for a 'knife' don't call for that.


    David

  3. #3
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    i have observed this as well. imattempting to discover steel and heat treat differences and seeing which are better to use

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    Quote Originally Posted by goodshepherdknives View Post
    i have observed this as well. imattempting to discover steel and heat treat differences and seeing which are better to use
    Best way to figure that out, is to just try them out. Obviously takes time, but I guarantee you'll appreciate what you learn from it.

    I have a carbon-bladed Opinel that I've taken about as thin as is reasonable. No idea what the actual edge angle is, but I've zero-ground it down to very, very thin. It is very delicate and vulnerable to edge impacts. But, for fine slicing, it's a dream. Goes through thick leather like a laserbeam. That alone is worth it, and I have no regrets in taking it that far.


    David

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    Quote Originally Posted by Obsessed with Edges View Post
    Best way to figure that out, is to just try them out. Obviously takes time, but I guarantee you'll appreciate what you learn from it.

    I have a carbon-bladed Opinel that I've taken about as thin as is reasonable. No idea what the actual edge angle is, but I've zero-ground it down to very, very thin. It is very delicate and vulnerable to edge impacts. But, for fine slicing, it's a dream. Goes through thick leather like a laserbeam. That alone is worth it, and I have no regrets in taking it that far.


    David
    um this is what im more looking for. ive done a test on peperboard over this year as cereal boxes ect gathered up, and i measured how many feet long each one cut before it wouldnt shave. it would get stropped back to shaving though so it wasnt dull, it was just edge stability. they all started 16k finish edge would whittle hair. some were fromfactory dimensions, some were my own reprofiling.
    i just pulled them off the shelf and went after making sure they were sharp. not any of these knives are similar. it was just something i did for fun and still plan on adding to someday. next test will be a taped off limited quantity of edge cutting manila rope. no they werent all the same edge geometry/blade shape/thickness/hardness, i just did it

    Spyderco 440c 90 feet *toothy 600 grit* the knife tested here was the cat with a 2 1/4 in. edge length
    Spyderco 8cr13mov 96 feet 40 ( the tanacious 3 inch cutting edge, sharpened pretty thin
    Spyderco 3cr13mov 65 feet ( the grasshopper
    Benchmade aus8 72 feet 35 strops (ambush at 4 inch cutting edge length
    Spyderco vg 10 357feet 75 strops ( stretch 3 1/4 cutting edge length
    Spyderco zdp 189 195 feet paperboard, 45 corrugated (manbug 1 3/4 edge length
    Benchmade 154cm 144 *thing profile hollow ground* (griptillian 3 1/2
    Buck 420hc 40 feet *thin profile hollow ground short blade* ( buck maverick 2 1/4 cutting edge
    Boker 440 c 60 feet ( gents scalpel 3 inch cutting edge length
    Benchmade N690 180 feet 15 strops to shave again (monochrome 3 inch cutting edge
    Benchmade d2 155 required cardboard to strop several times (bone collecter grippy, i dont have it
    Benchmade S30V 145 feet *thin profile ( dejavoo 4 inch cutting edge length

    knives i still have to test are sr 101, carbon V, esee 1095, gerber 12c27n, vg 1, and some others.
    Last edited by goodshepherdknives; 05-23-2013 at 11:19 AM. Reason: sigh what a mess ive made... elaborating

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    The Spyderco VG-10 really jumps out, in that list (357 feet of cardboard). If it were me, I'd be looking real close at what's special about that edge, and try to closely emulate it's physical characteristics in some of the others (edge angle, grind V/Convex, blade thickness, etc.).

    The downside in attempting to compare all these is, there's so many other variables at play, besides the steel and sharpening & finishing method. Even at the same edge angle, the overall blade thickness really makes a difference, due to the 'wedging' of the blade into the material. Even the 'test' material itself (the cardboard) is hugely variable in how it cuts. Lots of 'impurities' are built into it (even dirt), especially if it's made from recycled materials.

    The upside to all that is, it's great fun to keep experimenting with it. No shortage of variables to individually tweak, and therefore an endless number of 'projects' to learn from.


    David
    Last edited by Obsessed with Edges; 05-22-2013 at 05:58 PM.

  7. #7
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    definately true, and these were things i thought of also but i didnt really have much else to do. my next idea was to try the top five or three or howver many and use something like paracord and tape off all but say an inch so that way the same square foottage is being used so to speak and see if i can get some more accurate results. perhaps then it will give me a good idea of where to start with for my own projects, and see where to start. then i could test three of the same thickness and grind, have someone pro heat treat them since i dont have the means, test again on sever al materials, and pick my favorite

  8. #8
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    thinner edge stability




    Here's my take on this issue.


    I love thin edges and thin blades where appropriate.

    Some steels lend themselves to this more then others.


    Take a super tough steel like Crucible's CPM-3V.

    It can take a thin edge behind the edge, or a thin overall cross-section, even at a hardness that offers great edge retention.

    Other steels would require a thicker cross-section to achieve similar levels of toughness.


    What I don't like, and something I often see from some of my favorite knifemaker's, is the trend to make knives in tougher steels using the same cross-section as their lesser counterparts, thus loosing the advantage gained by the superior steel.





    Big Mike

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    in my opinion you are looking for "simple" tool steels with a proper ht aiming the top of their hardness ange. you are in the custom territory.

    i have a couple of performance oriented custom fixed blades. some are 145sc steel, 1,45%C and about nothing else. outstanding steel. one is c130, the same a bit less clean and 1,3C, some are 115w8/1.2442 tungsten steel, some 110WCrV5/1.2519/silversteel.... all work wonder for keeping the fresh of the hone edge longer ąt the shallowest angles .... something no production stainless can offer.


    japanese kitchen knives also comes to mind, aogami super and shirogami 1 (basically japanese c130)... but not so much folders or utility fixed blades in those steels.

    another great exemple of heat treat doing most of the job. my caly 3.5 is a great knife, with aogami super, great steel. HT'd by spyderco with customers in mind it doesnt hold a candle to simpler steels pushed higher in hardness.

    for extreme low angles forget high carbide stainless.

  10. #10
    Quote Originally Posted by goodshepherdknives View Post
    hello all. im a fan of either thick beastly knives like 5/16ths inch thick
    Question: why?

  11. #11
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    From the test numbers I can say your testing is flawed.
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    Quote Originally Posted by knifenut1013 View Post
    From the test numbers I can say your testing is flawed.
    Can you please elaborate?

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    Try to get some very hard AEB-L/13C26, 1095, M2, M4, O1, and/or 52100. This will all be custom type knives. Hardness should be at least 62 HRc.

  14. #14
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    You might find the following interesting related to steels and very low angles. It is done by metallurgist Roman Landes.

    Knife Edge Diagram

    Here is what he had to say:

    Quote Originally Posted by Roman Landes View Post
    Dear Colleagues,

    liked

    http://www.schmiedecafe.com/forum/at...ttachmentid=83

    The following is also a good idea about Edge Stability:

    http://www.smt.sandvik.com/en/produc...eel-knowledge/

    You will see there are pictures that show a fine micro structure steel like 12C27 compared to 440C.

    you find a PDF download in english as one of my latest works, in steel & knife research ongoing in Germany.
    To introduce myself I am knife maker and damascus smith since 1987 in Germany. My profession is graduated engineer in Automotive engineering and Material Science. Meber of the German Knifmakers Guild sinc 1993.

    I am also author for the German Book, Messerklingen & Stahl (M&S) Technologische Betrachtung von Messerschneiden (Knife blades and Steel, A technological survey on knife edges © 2002 Wieland Verlag, Bruckmühl, Germany) witch has successfully established a high quality discussion base on scientific research towards knifes and steel. The base of the Book was developed in the early 90’s when I was in my studies.

    With this download, you get a little goodie, extracted from the upcoming new book Messerklingen und Stahl, Praxishandbuch der Stähle (Knife blades and Steel; The Practical Handbook of Steels © 2005 Wieland Verlag, Bruckmühl Germany)

    What is the download about?
    The download shows the so-called “model of the cutting edge” taken from (M&S©2002).
    The actual book will show around 50 commonly known tool steels/ -alloys used for knife applications (e.G. ATS 34, 52100, RWL 34, L6, Vascowar, M4,…) an the way to treat them according to this application.

    Furthermore, one will see the abilities of the steel used supporting qualities essential for knife application (e.g. edge holding, wear resistance, sharpen ability, cutting ability, cutting edge stability, corrosion resistance,…), SWOT- Analysis…

    The model of the edge provided here, shows 5 selected reference alloys commonly known in the worldwide knife society.
    · 1.4125 (440C) Reference for traditional stainless steels
    · CPM S90V Reference for modern stainless PM-steels
    · Talonite Reference for Chrome Cobalt Alloys
    · 1.2510 (O1) Reference for hypereutectic tool steels
    · 1.2379 (D2) Reference for 12%-Chrome Cutting Steels

    What Do you see?
    What you see is the 1000x magnification (means all at the same scale) of the inner structure (microstructure) of this alloys, shown as micrographic pictures, in heat treated condition (Austenizing, Quench, Cryo, Temper in multiple cycles; except Talonite) Etching: Beraha 1.

    The white spots, are the so-calles Carbides responsible for the wear resistance in a alloy of this kind (The Teeth), surrounded by the Matrix (Meat) (Martensit, except Talonite)

    The sheet is designed to get folded on the edges marked. What you get when you do so, is the model of the edge 1000x magnification in 3D. By using the scale of the angel (Adjust in back light with single print) you can adjust every edge geometry between 15° and 90° edge angle.

    This means, having the model in 3D in front of you and assuming there is a local limited load applied from a side force towards the edge (occurs constantly in the normal use of a knife), this force will deflect the edge and in dependence of the load, and the steel can take, the edge will draw back in line or chip locally (wear and loose edge).

    The carbides will play a major role in the behavior of the steel in the edge
    Since they are very hard and brittle, in a fine cutting edge, carbides are the first point to start with chipping, especially when the are to many in relation to the surrounding (meat) or the carbides are so large, e.g. when they will fit nicely into the full range of sharp and dull limits1)

    Note, the large carbides of the alloys shown, will by no means get any significant change in size, during the complete heat treatment cycle (except 01, if hardened at to high temperatures, the carbides will dissolve completely and a mess of retained austenite and coarse brittle Martensit-grain will be there).

    What you can do with it now?

    Taking into account, that a sharp edge1) is around 1µm on the tip and a dull one1) is around 10µm in width, if a critical load to the edge is applied (wear of the edge), the different alloys behave different at different angles adjusted.

    Print the download (use A4 for the print-format), fold at the 3 lines marked and start adjusting the angle.

    I am sure this will help, to explain something…

    ...and hopefully start discussion …

    Best regards Roman

    Original thread:

    http://www.bladeforums.com/forums/sh...79#post3043379

    Here are also some definitions and you can see the difference between a knife steel such as 12C27 and 440C in microstructure at the edge.

    http://www.smt.sandvik.com/en/produc...eel-knowledge/
    Last edited by marthinus; 05-23-2013 at 06:19 AM.

  15. #15
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    Quote Originally Posted by singularity35 View Post
    Can you please elaborate?
    My first clue was that VG-10 was beating everything, my second was that none of the knives had enough similarities to conclude a proper result.
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    Quote Originally Posted by singularity35 View Post
    Can you please elaborate?
    yes he was butt hurt his favorite wasnt on top

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    Quote Originally Posted by knifenut1013 View Post
    My first clue was that VG-10 was beating everything, my second was that none of the knives had enough similarities to conclude a proper result.
    my testing was what it was. a two inch zdp 189 blade was better than a 2 inch 420hc blade. the spyderco 440c blade had a different kind of edge finish, some were thin, some were not. i have not tried all of the steels with all of the possible configurations to do a knife, im not God. i was just pulling them off the shelf and trying them over time and recorded them, i didnt ask questions. i dont have all of the different steels available in my personal collection inall of the same blade length in all of the same grind type, just chill it was just for the fun of it.

  18. #18
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    Quote Originally Posted by Magnaminous_G View Post
    Question: why?
    your scion toaster is ugly, why drive it? different people like different things. i enjoy my cold steel recon scout at 5/16ths inch thick. i dont use it to remove splinters i use it to cut trees down. my spyderco bug does not do well at falling trees but it does very well at opening boxes and cleaning dirt from under my nails. although i generally could use the scout for that if i had it, because there is no kill like overkill, so i would open a granola bar wrapper with a katana just because i can.

  19. #19
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    I have a favorite?

    There are things called test procedures, there is a reason they are followed. If ignored then you just have a bunch of random numbers.
    The first sharpening
    The Burr
    How to make a strop


    For sharpening inquiries email me at: traditionalsharpening@gmail.com
    Free return shipping on orders over $50

  20. #20
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    Quote Originally Posted by knifenut1013 View Post
    I have a favorite?

    There are things called test procedures, there is a reason they are followed. If ignored then you just have a bunch of random numbers.
    yes they are a bunch of random numbers. i never claimed that i was trying to prove in the above test which was better by brand or steel, i was simply stating what which was as a went over a few months to keep a record myself. i used it as an example to my original question which has been completely ignored. i did not jump up and down explaiming "whoo hoo this ones this best and is better than all the rest" claiming it was number one, i did not submit this test to a certain brand and tell them they arent good knife makers. it was an inicial what i had on hand at that time test i did from my collection

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