CPM SPY27 | Edge Performance

[Bolster]

I updated the OP
With a rope cut test between S30v and SPY27

Excellent! Thanks much for conducting and publishing this test!

[elena86]

Looking forward to the Millie in SPY27 :spyder:

[The Meat man]

Any updates on the tests?

I updated the OP
With a rope cut test between S30v and SPY27

Thanks! Good test.

[Deadboxhero]

I’ve always been curious about the BESS testing scores. It just seems, to my inexperienced self, like the results could vary widely even at the same sharpness.
How exactly do you test the knives with it to ensure somewhat reliable results?

That topic deserves it's own thread.

I've been using this piece of equipment for two years now, I've had multiple phone conversations with the creator of the BESS Tester to ensure I have been using best practices and that I'm using it to get the most repeatable results.

[Cl1ff]

That topic deserves it's own thread.

I've been using this piece of equipment for two years now, I've had multiple phone conversations with the creator of the BESS Tester to ensure I have been using best practices and that I'm using it to get the most repeatable results.

Thanks, that’s really good to hear!
I’d be interested in following a thread about the proper procedure and examples of repeatable results.
I had no reason to suspect you weren’t being diligent as with the other parts of the tests, but I do have more confidence in the results now that I’ve seen it stated.
Science is a huge part of my life, so I appreciate solid methods when testing a hypothesis like yours.

[sal]

Hi Cl1ff,

This has been a question for decades. First we built our own cutting test machine. ( early 90's). Then we bought and set up a CATRA again to try to answer this question. These days, we use the CATRA, Real World Testing, (RWT) and our forum participation to bring the truth closer.

sal

[Cl1ff]

Hi Cl1ff,

This has been a question for decades. First we built our own cutting test machine. ( early 90's). Then we bought and set up a CATRA again to try to answer this question. These days, we use the CATRA, Real World Testing, (RWT) and our forum participation to bring the truth closer.

sal

The work is greatly appreciated!
This forum, and Spyderco by association, has taught me so much about every aspect of a knife. To participate in steel testing discussion with makers like yourself and Deadboxhero (or BBB? Shawn?) is a real privilege!

I try to use the internet to its fullest in order to learn from the experts. I find myself incredibly lucky to have already learned so much from the best out there in all my interests.

I’d like to start designing, making, and testing knives one day where this information about test procedures and tools will, I think, prove incredibly useful. So once again, thank you to everyone here for sharing so much of your knowledge and experience.

Spy27 is a really interesting steel that I think will be a favorite of mine in the Spyderco lineup.

[Bolster]

Those of you who can "read" a micrograph, what does Dr. Thomas' photo of SPY27 tell you?

[Deadboxhero]

Those of you who can "read" a micrograph, what does Dr. Thomas' photo of SPY27 tell you?

The white dots are Carbides, you can see the size and volume of them.

Higher volume with larger size generally means less tough more wear resistant.

Lower volume with smaller size generally means more toughness less wear resistant and sometimes less strength.

High volume with small Carbides generally is still not going to be crazy tough but tougher than the same volume of larger carbides

There are also hidden features we can't see.

You can't see what type of carbides they are, you can't necessarily see the soft retained austenite, can't really see grain size (unless some prior Austenite grains are showing) and you can't see carbon and other elements that are in solution which are huge factors.

Those features are crucial and seem to be elusive to aspiring metal nerds and almost requires some heat treatment experience to fully appreciate.

The difference in shades in the regions between the carbides in the micrograph is "artifact/noise" its just how the steel responds to the etch more than anything useful or conclusive to learn from.


With these 1000x micrographs its just to look at the carbides, the overall size and volumes.

[Bolster]

...There are also hidden features we can't see.

You can't see what type of carbides they are, you can't necessarily see the soft retained austenite, can't really see grain size (unless some prior Austenite grains are showing) and you can't see carbon and other elements that are in solution which are huge factors.

Those features are crucial and seem to be elusive to aspiring metal nerds and almost requires some heat treatment experience to fully appreciate.

Aha, excellent. Thank you, especially for the "and what you can't see" portion, which I'd not considered previously.

Do you have any opinion on the "clumpiness" of the carbides in the photo, or is that just a random distribution? There is really just the one clump; could be a fluke.

The fewer carbides in SPY27 cf S30V would correlate well with your test, would it not?

The relatively small carbides spaced well apart might indicate a tougher steel, but I think SPY27 is only around the 8-11 ft/lbs range for toughness, no? That puzzles me a bit.

[Bolster]

I'm probably illustrating BBB's point that there's a lot you can NOT determine by micrography, because looking at CPM154 vs SPY27, I'd have guessed that SPY27 would be the tougher steel. But according to Dr. Thomas' findings, SPY27 is in the 8-11 ft lb range, whereas CPM154 is nearly twice as tough. (Granted, the comparison is off by 2 Rc, and that might explain it--maybe CPM154 would be in SPY27's range at 61-62 Rc.)

[Deadboxhero]

...There are also hidden features we can't see.

You can't see what type of carbides they are, you can't necessarily see the soft retained austenite, can't really see grain size (unless some prior Austenite grains are showing) and you can't see carbon and other elements that are in solution which are huge factors.

Those features are crucial and seem to be elusive to aspiring metal nerds and almost requires some heat treatment experience to fully appreciate.

Aha, excellent. Thank you, especially for the "and what you can't see" portion, which I'd not considered previously.

Do you have any opinion on the "clumpiness" of the carbides in the photo, or is that just a random distribution? There is really just the one clump; could be a fluke.

The fewer carbides in SPY27 cf S30V would correlate well with your test, would it not?

The relatively small carbides spaced well apart might indicate a tougher steel, but I think SPY27 is only around the 8-11 ft/lbs range for toughness, no? That puzzles me a bit.

All good questions, the rabbit hole goes deeper and deeper the more you learn.

Everytime just looking for simple answers but just seem to end up with more questions.

I'm curious to see how the edge stability compares to a steel like S30v, I feel I have a test design that can reduce a lot of variables.

[Baron Mind]

Just wanted to thank and commend you for performing and sharing your cut test. The depth, detail, and precision of your testing is impressive.

[Deadboxhero]

Just wanted to thank and commend you for performing and sharing your cut test. The depth, detail, and precision of your testing is impressive.

Thanks Baron, I appreciate it :)

[Bolster]

All good questions, the rabbit hole goes deeper and deeper the more you learn. Everytime just looking for simple answers but just seem to end up with more questions.

It certainly seems that way! I've arrived at the "sophomore" level of steel knowledge: I don't know anything, but I know that I don't know anything. That's one step beyond the "freshman" level, where you don't know anything, and you've no idea that you don't.

I'm curious to see how the edge stability compares to a steel like S30v, I feel I have a test design that can reduce a lot of variables.

If you can figure out how to reduce extraneous variables, more power to you. That's the name of the game in science, isn't it. Will stay tuned for that....!

[Larrin]

SPY27 and CPM-154 have roughly the same toughness. I did a whole range of CPM-154 toughness experiments and none of them matched that original value so I threw it out. I don't know what happened with it. https://knifesteelnerds.com/2020/03/16/ ... periments/

[Bolster]

SPY27 and CPM-154 have roughly the same toughness. I did a whole range of CPM-154 toughness experiments and none of them matched that original value so I threw it out. I don't know what happened with it. https://knifesteelnerds.com/2020/03/16/ ... periments/

An interesting mystery, and thanks volumes for the retest. Intuitively, CPM-154's re-test position aligns with expectations a bit more. Comparatively, this improves the "toughness reputation" of XHP, SPY-27, S35VN, and M390 a bit -- they're no longer significantly outclassed by CPM-154.

(Truth be told, I'm really interested in trying some Nitro, Nio, or AEB-L at around 62 Rc for a backpacking blade.)

[thewoodpecker]

Thanks Shawn! Good to hear!

I'll be waiting (praying) for a Military.

THAT would be a dream spydie for me :spyder: Cobalt blue G10 handle of course :eek:

Military/M2 in Spy27 and Mineral Blue G10 for the win.

[Ranger_Ike]

Today I field dressed and skinned two deer with my N5 in SPY27. This process included cutting up through the brisket as well as splitting the pelvis. Also there are many times you are cutting up against bone, such as when removing the front legs at the knees, and cutting around the hipbone and joint.

After filed dressing both deer, and skinning/quartering one, I checked sharpness and found it was no longer shaving hairs, but it was cleanly and easily slicing paper. The only stone on hand was a cheap cabelas brand diamond stone that is so old it almost felt smooth. I did 10 light passes on each side and then 3 alternating passes. This brought the blade back to hair popping sharp and I continued with the second deer.

After finishing the second deer the edge will scrape shave.

I am extremely impressed with the edge holding of SPY27. I can see it being a great steel for a fixed blade or folding hunter. The ease of sharpening is outstanding for how much edge retention you get.

Thanks Sal and company for an amazing steel. Quickly becoming a favorite of mine.

[JSumm]

One of my favorite steels. Great feedback.