Spyderco CPM-SPY27

Discussion in 'Spyderco' started by DA170, Jun 10, 2020.

What model with CPM-SPY27?

  1. Para 3 Lightweight

    21 vote(s)
    36.8%
  2. Manix 2 Lightweight

    13 vote(s)
    22.8%
  3. Native 5 Lightweight

    17 vote(s)
    29.8%
  4. MULE TEAM 28

    14 vote(s)
    24.6%
Multiple votes are allowed.
  1. Mark Spark

    Mark Spark

    101
    Jun 1, 2020
    Your test insights about thickness and knife angle are very interesting to me. I have a couple comments.
    I’ve also noticed the importance of the angle or squareness of the blade to the material. To test sharpness I try to push cut computer paper. Only the very sharpest knife will push cut paper at 90 degrees. As soon as you tilt the blade a little, a duller blade (still sharp) will push cut. This agrees with your observation.
    Secondly, I’m fascinated by the behind-the-edge thickness (TBE) issue. For cutting wood or thick cardboard I’ve found TBE outweighs sharpness. Yet it’s never specified and rarely given in reviews. I’ve found the difference between 0.025” and 0.020” is enormous. A knife under 0.020” is a precious thing. For example, my Caribbean, my GBF 2, my Tenacious.
    Spyderco’s from Taichung are typically better in TBE than from Golden. But it’s inconsistent by model and doesn’t correlate with price. I don’t understand this. My Tenacious is 0.017-0.020 but pm2’s are around 0.022-0.024. I paid $240 dollars for a Chinook 4 that’s 0.030”. That’s disgraceful.

    Two things I’d like to see manufacturers work on: 1) Better TBE, 2) stop ruining temper during sharpening. How hard can it be to cool the blade during sharpening? Anybody can do it at home with a Tormac.
     
  2. Rusty_shackelford

    Rusty_shackelford Gold Member Gold Member

    May 3, 2013
    Could someone please educate me in behind the edge thickness?
    I thought I had a general idea of what it was, but if there’s some correlation between price and bte thickness, I’m completely lost.
     
  3. Mark Spark

    Mark Spark

    101
    Jun 1, 2020
    It’s the blade thickness where the shiny edge bevel meets the blade grind. If the edge bevels are different each side, it’s the thicker of the two.
    I’m lost too. I don’t understand why TBE is as high as it is on most knives. It can’t be for edge toughness. My Buck 119 hunting knife is 0.025”, same as the Spyderco Military. But the Buck is 0.200” thick and can clearly handle chopping and hacking. You could probably hammer it through a nail. Large as it is, a Military is for lighter tasks.
    On the other hand, I own a Cold Steel Holdout, a completely impractical 6” blade murderous weapon. If it were 0.040” behind the edge no one would care since no on will use it for day to day cutting. But it’s 0.013-0.015”, the thinnest in my collection. Maybe they made it like that so Lynn could demonstrate cutting through a side of beef in one swing. I have no idea.
     
  4. Rusty_shackelford

    Rusty_shackelford Gold Member Gold Member

    May 3, 2013
    Wouldn’t this have more to do with the blade stock thickness and the type of grind?
    I just don’t get what price has to do with it?
    Just to use your earlier examples of the tenacious and chinook.
    Are they both the same thickness and have the same grind?
    Should a more expensive knife spend more time on a grinding belt?

    I should have started my own thread on this I suppose.

    Sorry for the thread jack OP.
     
    DA170 likes this.
  5. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    The geometry subject is an interesting one and I wish it was discussed out in the open more. I feel that I have a layman's understanding.

    What I think I understand is:

    In terms of thickness behind the edge, going thinner means better cutting efficiency. With it being thinner, the media you're cutting doesn't have to spread as wide in order to pass the shoulder of your edge bevel and then slide up the blade.

    By going thinner behind the edge, your knife will require less pressure to cut, therefore causing less compressive forces at the apex which in turn aids in edge longevity.

    In terms of stock thickness, thinner simply makes it easier to cut through things. The additional pressure required with thicker stock, I believe, is absorbed by the sides of the blade overall, and not the apex. However if your fighting the knife through something, you'll end up putting all kinds of lateral pressures on the apex which does not help edge longevity.

    The downside of thinner stock is that you give up a lot of strength and rigidity. With going thinner behind the edge, especially with some steels, crack propagation and chip size becomes more of an important subject for some usage types.

    The full flat grind that Spyderco uses, on the Para3 for example, allows them to use relatively thick stock and be relatively thick behind the edge, while still maintaining good cutting efficiency.
     
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  6. CarsonWayne

    CarsonWayne Basic Member Basic Member

    226
    Mar 2, 2020

    I really enjoyed reading this, and there is a SPY27 in the mail headed my way as I type. While I love the Para 3, I am no fan of the FRN scales. I gave away my all black BD1N version because it was just too slippery when dry. It is to the point of being dangerous if your skin leans to the drier side, like mine.

    Back on topic... if this steel excites me, I will do a blade swap into a skinny-modded micarta-scaled version that's currently home to an S30V cutter.

    Thanks for all of the time and energy that went into this experiment, and then for being able to share your results in a manner that is easily understandable. Well done.
     
    Last edited: Jun 25, 2020
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  7. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    With my previous test results being so high for SPY-27, I wanted to retest it, and finally had some time today.

    I put the same edge on it, cut the same cardboard, and conducted the test exactly the same.

    I tested the edge every 30 cuts.

    In the previous test, I felt some extra drag through the cardboard and checked the edge half way through my 14th set of 30 cuts through 9" cardboard sections. That works out to be 303 feet. The failure point would have happened within the last 15 cuts, because that's the gap between testing points.

    With this test, I got 315 feet while holding at 90 degrees to the cardboard. The end snuck up on me, I didnt realize how deep into the test I was, and simply checked the edge after set number 14.

    So basically, with both tests the result is approximately the same, which is that SPY-27 fails the paper test at about 300 feet when tested in a way that causes S30V to fail at about 150 feet and M390/20CV to fail consistently, depending on which knife, at about 170 to 250 feet.

    So I will go ahead and make the claim that when it comes to maintaining a fine edge while cutting cardboard, SPY-27 has superior edge retention to S30V, M390, and 20CV

    This would be expected seeing as how SPY-27 is run harder than most examples of those steels.

    Due to having less carbides, and not being substantially harder, through the evolution of an edge from sharp to dull, or through more abrasive material, I'd expect SPY-27 to wear in a similar way to S30V. It really depends on what's being cut.
     
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  8. CarsonWayne

    CarsonWayne Basic Member Basic Member

    226
    Mar 2, 2020

    These are interesting results. Again, thanks for the effort involved with presenting this exercise.

    Your last comment made me stop and think - how would SPY27 perform in comparison to other popular stainless steels in cutting tests against various common media? Ultimately, what is the best way for the layperson to identify their use(s) for a knife, and through a catalog of recorded test results, determine the appropriate steel?

    Say a customer is looking to buy a Para 3 and they want to know which steel would perform best at slicing hundreds of plastic zip ties, carving wood, cutting heavy cardboard, dressing game or chopping vegetables. All of these tasks could be handled by any sharp edge with a handle, but certain steels would be better suited for each of them if that was its primary use.

    Does a database like this exist? Am I crazy?
     
  9. Sal Glesser

    Sal Glesser Moderator Moderator

    Dec 27, 1998
    Hi SubMicron,

    Thanx much for the effort and for sharing.

    sal
     
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  10. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    There isnt a database because the results will vary depending on how the end user will use, sharpen, and maintain the knife.

    Its kind of like asking what color is best.

    The tests through clean cardboard, perhaps are a good representation for light non abrasive use such as the typical EDC, where a sharp clean edge will be maintained continuously.

    Rope cut tests with a cutting board perhaps are more relevant to other usage styles, especially those that involve a cutting board.

    And then we have CATRA, easily the purest test of the steel itself, with every conceivable variable eliminated. A CATRA test dulls the edge significantly, taking it to a dullness level that an edge snob would never see. Meanwhile a CATRA test probably lines up best for people who cut abrasive things and for people who completely dull their knives before sharpening.

    When the knife enters a true working environment where it will see a volume of work, a variety of tasks, and hard use, stainless steels may not be the best option, not only for edge retention, but also toughness.

    Since we're not talking about a $15 tool from the hardware store here, some level of simple maintenance such as applying an anti-corrosive product shouldn't be out of the question. Even a box cutter requires maintenance through the changing of blades.

    Still, some people will only purchase a steel that's stainless. To have a steel be "stainless" you're really sacrificing a lot of performance to get it.

    S30V, often referred to as the entry level "super steel" simply is not super. It's a well balanced powder steel, that's technically stainless, with mid level performance.

    M390/20CV bring more of everything to the table and maintain balance.

    S90V and S110V throttles up edge retention through high carbide wear resistance but sacrifices strength, sharpen-ability, and fine edge holding abilities, especially S110V.

    So far SPY-27 is showing me edge holding performance above the M390 class, but with a high degree of sharpen-ability, and seemingly better fine edge holding characteristics. Due to a few things, SPY-27 may be a significantly better steel then what was initially advertised. I care about the fine edge holding characteristics the most.

    We need more testing.

    So far I'm very happy with the edge that comes off of both diamonds and ceramics.
     
    Last edited: Jul 1, 2020
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  11. Mrs_Esterhouse

    Mrs_Esterhouse

    102
    Apr 9, 2019
    SPY-27 looks like it's not boring.
     
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  12. Mrs_Esterhouse

    Mrs_Esterhouse

    102
    Apr 9, 2019
    This is really exciting, but KSN predicts in Thermo-Calc that SPY-27 will underperform S30V in CATRA and even more so with M390. How can your result be so different? Don't get me wrong, I'm glad it is and I believe you, but the discrepancy seems huge. Maybe there's some underlying factor not being accounted for; I don't know....
     
    Last edited: Jul 1, 2020
  13. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    It's really a good question.

    They're two totally different tests and different things are being tested with each.

    CATRA removes all geometry and human variables and is a pure test of the steel. Sillica impregnated card stock is used and the sharpened edge thats tested, gets dulled completely. Basically its sand filled cardstock which is very abrasive.

    Cardboard testing by hand is not a pure test of the steel. It is however a test of the steel on balance with testing the geometry of the knife and it gives a good idea of what will happen with the fine edge. There's geometry and human variables, however the bulk of these can be controlled reasonably well if you hold the knife square to the cardboard at 90 degrees.

    I define a "fine edge" by its ability to cleanly cut through paper. This is referred to as a "working edge" by YouTube cut testers and they define the Fine Edge as its ability to shave arm hair. I dont want to get into arm hair specs, but we all have slightly different hair, also the pressure used to shave is an enormous variable. The best way to eliminate the arm hair variables is to not test them.

    Cardboard is a fantastic test media because its consistent and readily available. Copy paper is also readily available and is consistent.

    Clean new cardboard is almost entirely cellulose and virtually completely free of sillica. It's a much, much less abrasive test media. Also with a cardboard cut test, the knife never gets anywhere near as dull as a CATRA test.

    A CATRA test is the most (only) accurate way available to measure Wear Resistance from sharp to dull.

    A controlled cardboard test measures the front end sharpness.... the fine edge basically. While wear resistance definitely is a factor when cutting cardboard, so is the stability of the fine edge. In fact I believe a cardboard cut test is testing the stability of the fine edge more than its testing wear resistance.

    That theory is supported by the performance of 14c28n in cardboard cut tests. It's a very inexpensive "budget" steel that consistantly performs on a similar level to typical M390 in this style test. 14c28n, from what I understand, is very tough and has a small grain size which is great for a fine edge.

    Like 14c28n, SPY-27 out performs through cardboard tests because of edge stability. Slightly higher hardness plus other things are causing that in SPY-27.

    Specifically what's being tested in a cardboard cut test with clean new cardboard is the knife's ability to cut clean new cardboard while held at a specific angle relative to the cardboard. Through those results we can infer what will happen with the fine edge through light to normal cutting through non-abrasive things.
     
    Last edited: Jul 1, 2020
  14. nephron

    nephron Gold Member Gold Member

    Aug 3, 2017
    Are they factory sharpness or do they sharpen each knife to the same degree? Seems like the knives in question would have to be the same sharpness.
     
  15. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    As previously mentioned, I sharpened them the same for every test.
     
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  16. SubMicron

    SubMicron Gold Member Gold Member

    335
    Feb 2, 2020
    It's no problem, I'm happy to do it. I needed to know what SPY-27 can do. Thanks for bringing another great steel to market!

    Im interested in repurchasing the steel. Are there any chances of a Lil Native being released in SPY-27?
     
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  17. Sal Glesser

    Sal Glesser Moderator Moderator

    Dec 27, 1998
    Hi SubMicron,

    It all depends on demand.

    sal
     
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  18. kwazyjuice

    kwazyjuice

    Feb 10, 2013
    Great read and testing here on SPY27, thanks to SUBMICRON and the OP for contributing and starting this thread. I just received this one Monday and its crazy sharp!

    [​IMG]
     
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  19. DA170

    DA170 Gold Member Gold Member

    316
    Mar 12, 2020
    Hope you enjoy the knife! Still keeping an eye out for the Mule.
     
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  20. d00mtr33

    d00mtr33 Gold Member Gold Member

    406
    Sep 4, 2013

    I agree, geometry plays a huge part in wear resistance and cutting ability, especially in softer materials. I have an Elmax para 2 with a Krein regrind to about 0.005 bte and even when it's dull it cuts just as well if not better then a para 2 with a 0.025 bte. I'd imagine it would serve amazing as a parring knife with no need for sharpening except for things like tomatoes. I have a few knives in the under 10 thou category and the way they cut is something else. I have the original Nilakka that was zero ground with just a microbevel. It was terrible out of the box, sharpening a pencil and a few cuts into cardboard damaged the edge. After a few sharpenings and doing the sides as well it performs much better and is in the 0.003 to 0.005 range. Then a have an old school Shami in Damasteel with a very thin hollow grind. Most of it is 0.007-0.008 and it takes a 1/4" to break the 0.010 mark. Really nice cutter and one of the few hollow grinds that doesn't thicken at the edge.
    I wish more companies made thinner ground knives. They're already insuring themselves against bad users by running steels softer for more toughness but then they're diong double protection by giving us thicker ground knives. Personally I'd rather have better heat treat/higher hardness since a regrind is doable but you'd need a reblade to get a different heat treat. Huge price difference between the two.
     

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